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TUGAS & LATIHAN : Membuat Java Program Perhitungan Bunga Investasi Dengan CLASS TextIO() Dan Membuat Input Data Profile Pada Netbeans IDE

Posted by CHRISTIANTO D,WIBOWO | D3MI-2016 STMIK BUMI GORA On Sabtu, Januari 21, 2017 No comments

Akhirnya terpecahkan permasalahan pada Tugas Dan Latihan TUGAS & LATIHAN : Membuat Java Program Perhitungan Bunga Investasi Dengan Scanner dan Control Statement Netbeans IDE, dimana ada satu point Tugas Dan Latihan yang ke-4 yakni Membuat Java Program Perhitungan Bunga Investasi Dengan CLASS TextIO() pada Netbeans IDE.
Setelah 2 hari terus memburu CLASS TextIO() pada master-master tutor Java, akhirnya terpecahkan permasalahan tersebut.

4. Menghitung bunga investasi selama satu tahun, berdasarkan masukan pengguna. Menggunakan menggunakan CLASS TextIO() sebagai input user,
TUGAS dan LATIHAN ini mengimplementasikan program sederhana yang akan menghitung jumlah bunga yang diperoleh dari investasi selama periode satu tahun. Jumlah awal dari investasi dan tingkat bunga adalah input oleh pengguna. Nilai investasi pada akhir tahun adalah output. Tingkat harus masukan sebagai desimal, bukan persentase (misalnya, 0,05 bukan 5%). Program ini membutuhkan TextIO untuk input. TextIO bukan merupakan bagian standar dari Java, sehingga harus dibuat tersedia saat program dikompilasi atau dijalankan.
Menggunakan CLASS TextIO() tidak sesederhana yang kita pikirkan ternyata dalam 1 package ada 2 class Java file yang harus kita buat. Untuk masalah ini kita akan membuat Packages bungainvestasi4 dan class yang kita buat :
  1. CLASS BungaInvestasi4.java
  2. CLASS TextIO().java
Pertama kali yang kita lakukan adalah membuat Java Program untuk CLASS BungaInvestasi4, berikut adalah source codenya :
/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package bungainvestasi4;
// @uthor CHRISTIANTO "GEMBLONG" DHARMA WIBOWO LEARN JAVA
public class BungaInvestasi4 {
    /**
     * Tugas Dan Latihan ini mengimplementasikan program sederhana yang akan 
     * menghitung jumlah bunga yang diperoleh dari investasi selama periode satu tahun. 
     * Jumlah awal dari investasi dan tingkat bunga adalah input oleh pengguna. 
     * Nilai investasi pada akhir tahun adalah output. Tingkat harus masukan sebagai desimal, 
     * bukan persentase (misalnya, 0,05 bukan 5%). 
     * Program ini membutuhkan TextIO untuk input. 
     * TextIO bukan merupakan bagian standar dari Jawa, 
     * sehingga harus dibuat tersedia saat program dikompilasi atau dijalankan.
     */
    public static void main(String[] args) {
   System.out.println("CHRISTIANTO 'GEMBLONG' DHARMA WIBWO LEARN JAVA");
   System.out.println("Menghitung Bunga Investasi Dalam Satu Tahun");
   System.out.println("-------------------------------------------");
        double investasi;  // Nilai Investasi Awal.
        double bunga;       // Suku Bunga Pertahun
        double keuntungan;   // Keuntungan Setelah periode 1 tahun.

        System.out.print("Masukan Jumlah Nilai Investasi: Rp.           ");
        investasi = TextIO.getlnDouble(); //ERROR

        System.out.print("Masukkan Suku Bunga Pertahun (dalam desimal): ");
        bunga = TextIO.getlnDouble(); //ERROR

        keuntungan = investasi * bunga;       // Menghitung keuntungan dalam 1 tahun.
        investasi = investasi + keuntungan;  // Keuntungan ditambahkan ke nilai investasi awal=nilai investasi setelah 1 tahun.
   System.out.println("-------------------------------------------");
        System.out.printf("Nilai Keuntungan 1 Tahun = Rp.%1.2f%n", keuntungan);
        System.out.printf("Nilai Investasi 1 Tahun  = Rp.%1.2f%n", investasi);

    } // akhir of main()

} // akhir of class BungaInvestasi4
Jika kita jalankan Java Program ini, akan menghasilkan ERROR, karena compiler Netbeans IDE tidak bisa meng-compile class TextIO() TextIO : Program ini membutuhkan class TextIO() untuk input. class TextIO() bukan merupakan bagian standar dari Java, sehingga kita harus membuatnya tersedia saat program dikompilasi atau dijalankan.
Seperti yang saya telah sebutkan diatas, kita harus membuat class metode baru, baca dengan rinci bagian ini :
  1. http://christcay.blogspot.com/2016/12/bagian-ke-enam-java-method-pada.html
  2. http://christcay.blogspot.com/2016/12/bagian-ke-enam-java-method-calling.html
  3. http://christcay.blogspot.com/2016/12/bagian-ke-enam-java-methods-passing.html
  4. http://christcay.blogspot.com/2016/12/bagian-ke-enam-passing-multiple-values.html
baru kita bisa memahammi untuk membuat 2 atau lebih class metode baru. Kita tinggalkan dulu ERROR tersebut sementara, kita buat class TextIO() agar Java Program kita bisa berjalan baik.
Berikut ini adalah source code untuk CLASS TextIO() :
/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package bungainvestasi4;
import java.io.*;
import java.util.IllegalFormatException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import javax.swing.JFileChooser;
import javax.swing.JOptionPane;

/**
 * TextIO provides a set of static methods for reading and writing text.  By default, it reads
 * from standard input and writes to standard output, but it is possible to redirect the input
 * and output to files or to other input and output streams.  When the standard input and output
 * streams are being used, the input methods will not produce an error; instead, the user is
 * repeatedly prompted for input until a legal input is entered.  (If standard input has been
 * changed externally, as by file redirection on the command line, this is not a reasonable
 * behavior; to handle this case, TextIO will give up after 10 consecutive illegal inputs and
 * will throw an IllegalArgumentException.)  For the most part, any other
 * error will be translated into an IllegalArguementException.
 * <p>For writing to standard output, the output methods in this class pretty much
 * duplicate the functionality of System.out, and System.out can be used interchangeably with them.
 * <p>This class does not use optimal Java programming practices.  It is designed specifically to be easily
 * usable even by a beginning programmer who has not yet learned about objects and exceptions.  Therefore,
 * everything is in a single source file that compiles into a single class file, all the methods are
 * static methods, and none of the methods throw exceptions that would require try...catch statements.
 * Also for this reason, all exceptions are converted into IllegalArgumentExceptions, even when this
 * exception type doesn't really make sense.
 * <p>This class requires Java 5.0 or higher. (A previous version of TextIO required only Java 1.1;
 * this version should work with any source code that used the previous version, but it has some new
 * features, including the type of formatted output that was introduced in Java 5 and the ability to
 * use files and streams.)
 */
public class TextIO {

    /* Modified November 2007 to empty the TextIO input buffer when switching from one
     * input source to another. This fixes a bug that allows input from the previous input
     * source to be read after the new source has been selected.
     */

    /**
     * The value returned by the peek() method when the input is at end-of-file.
     * (The value of this constant is (char)0xFFFF.)
     */
    public final static char EOF = (char)0xFFFF;

    /**
     * The value returned by the peek() method when the input is at end-of-line.
     * The value of this constant is the character '\n'.
     */
    public final static char EOLN = '\n';          // The value returned by peek() when at end-of-line.
 

    /**
     * After this method is called, input will be read from standard input (as it
     * is in the default state).  If a file or stream was previously the input source, that file
     * or stream is closed.
     */
    public static void readStandardInput() {
        if (readingStandardInput)
            return;
        try {
            in.close();
        }
        catch (Exception e) {
        }
        emptyBuffer();  // Added November 2007
        in = standardInput;
        inputFileName = null;
        readingStandardInput = true;
        inputErrorCount = 0;
    }
 
    /**
     * After this method is called, input will be read from inputStream, provided it
     * is non-null.  If inputStream is null, then this method has the same effect
     * as calling readStandardInput(); that is, future input will come from the
     * standard input stream.
     */
    public static void readStream(InputStream inputStream) {
        if (inputStream == null)
            readStandardInput();
        else
            readStream(new InputStreamReader(inputStream));
    }
 
    /**
     * After this method is called, input will be read from inputStream, provided it
     * is non-null.  If inputStream is null, then this method has the same effect
     * as calling readStandardInput(); that is, future input will come from the
     * standard input stream.
     */
    public static void readStream(Reader inputStream) {
        if (inputStream == null)
            readStandardInput();
        else {
            if ( inputStream instanceof BufferedReader)
                in = (BufferedReader)inputStream;
            else
                in = new BufferedReader(inputStream);
            emptyBuffer();  // Added November 2007
            inputFileName = null;
            readingStandardInput = false;
            inputErrorCount = 0;
        }
    }
 
    /**
     * Opens a file with a specified name for input.  If the file name is null, this has
     * the same effect as calling readStandardInput(); that is, input will be read from standard
     * input.  If an
     * error occurs while trying to open the file, an exception of type IllegalArgumentException
     * is thrown, and the input source is not changed.  If the file is opened
     * successfully, then after this method is called, all of the input routines will read
     * from the file, instead of from standard input.
     */
    public static void readFile(String fileName) {
        if (fileName == null) // Go back to reading standard input
            readStandardInput();
        else {
            BufferedReader newin;
            try {
                newin = new BufferedReader( new FileReader(fileName) );
            }
            catch (Exception e) {
                throw new IllegalArgumentException("Can't open file \"" + fileName + "\" for input.\n"
                                 + "(Error :" + e + ")");
            }
            if (! readingStandardInput) { // close current input stream
                try {
                    in.close();
                }
                catch (Exception e) {
                }
            }
            emptyBuffer();  // Added November 2007
            in = newin;
            readingStandardInput = false;
            inputErrorCount = 0;
            inputFileName = fileName;
        }
    }

    /**
     * Puts a GUI file-selection dialog box on the screen in which the user can select
     * an input file.  If the user cancels the dialog instead of selecting a file, it is
     * not considered an error, but the return value of the subroutine is false.
     * If the user does select a file, but there is an error while trying to open the
     * file, then an exception of type IllegalArgumentException is thrown.  Finally, if
     * the user selects a file and it is successfully opened, then the return value of the
     * subroutine is true, and  the input routines will read from the file, instead of
     * from standard input.   If the user cancels, or if any error occurs, then the
     * previous input source is not changed.
     * <p>NOTE: Calling this method starts a GUI user interface thread, which can continue
     * to run even if the thread that runs the main program ends.  If you use this method
     * in a non-GUI program, it might be necessary to call System.exit(0) at the end of the main()
     * routine to shut down the Java virtual machine completely.
     */
    public static boolean readUserSelectedFile() {
        if (fileDialog == null)
            fileDialog = new JFileChooser();
        fileDialog.setDialogTitle("Select File for Input");
        int option = fileDialog.showOpenDialog(null);
        if (option != JFileChooser.APPROVE_OPTION)
            return false;
        File selectedFile = fileDialog.getSelectedFile();
        BufferedReader newin;
        try {
            newin = new BufferedReader( new FileReader(selectedFile) );
        }
        catch (Exception e) {
            throw new IllegalArgumentException("Can't open file \"" + selectedFile.getName() + "\" for input.\n"
                             + "(Error :" + e + ")");
        }
        if (!readingStandardInput) { // close current file
            try {
                in.close();
            }
            catch (Exception e) {
            }
        }
        emptyBuffer();  // Added November 2007
        in = newin;
        inputFileName = selectedFile.getName();
        readingStandardInput = false;
        inputErrorCount = 0;
        return true;
    }
 
    /**
     * After this method is called, output will be written to standard output (as it
     * is in the default state).  If a file or stream was previously open for output, it
     * will be closed.
     */
    public static void writeStandardOutput() {
        if (writingStandardOutput)
            return;
        try {
            out.close();
        }
        catch (Exception e) {
        }
        outputFileName = null;
        outputErrorCount = 0;
        out = standardOutput;
        writingStandardOutput = true;
    }
 

    /**
     * After this method is called, output will be sent to outputStream, provided it
     * is non-null.  If outputStream is null, then this method has the same effect
     * as calling writeStandardOutput(); that is, future output will be sent to the
     * standard output stream.
     */
    public static void writeStream(OutputStream outputStream) {
        if (outputStream == null)
            writeStandardOutput();
        else
            writeStream(new PrintWriter(outputStream));
    }
 
    /**
     * After this method is called, output will be sent to outputStream, provided it
     * is non-null.  If outputStream is null, then this method has the same effect
     * as calling writeStandardOutput(); that is, future output will be sent to the
     * standard output stream.
     */
    public static void writeStream(PrintWriter outputStream) {
        if (outputStream == null)
            writeStandardOutput();
        else {
            out = outputStream;
            outputFileName = null;
            outputErrorCount = 0;
            writingStandardOutput = false;
        }
    }
 

    /**
     * Opens a file with a specified name for output.  If the file name is null, this has
     * the same effect as calling writeStandardOutput(); that is, output will be sent to standard
     * output.  If an
     * error occurs while trying to open the file, an exception of type IllegalArgumentException
     * is thrown.  If the file is opened successfully, then after this method is called,
     * all of the output routines will write to the file, instead of to  standard output.
     * If an error occurs, the output destination is not changed.
     * <p>NOTE: Calling this method starts a GUI user interface thread, which can continue
     * to run even if the thread that runs the main program ends.  If you use this method
     * in a non-GUI program, it might be necessary to call System.exit(0) at the end of the main()
     * routine to shut down the Java virtual machine completely.
     */
    public static void writeFile(String fileName) {
        if (fileName == null)  // Go back to reading standard output
            writeStandardOutput();
        else {
            PrintWriter newout;
            try {
                newout = new PrintWriter(new FileWriter(fileName));
            }
            catch (Exception e) {
                throw new IllegalArgumentException("Can't open file \"" + fileName + "\" for output.\n"
                                 + "(Error :" + e + ")");
            }
            if (!writingStandardOutput) {
                try {
                    out.close();
                }
                catch (Exception e) {
                }
            }
            out = newout;
            writingStandardOutput = false;
            outputFileName = fileName;
            outputErrorCount = 0;
        }
    }
 
    /**
     * Puts a GUI file-selection dialog box on the screen in which the user can select
     * an output file.  If the user cancels the dialog instead of selecting a file, it is
     * not considered an error, but the return value of the subroutine is false.
     * If the user does select a file, but there is an error while trying to open the
     * file, then an exception of type IllegalArgumentException is thrown.  Finally, if
     * the user selects a file and it is successfully opened, then the return value of the
     * subroutine is true, and  the output routines will write to the file, instead of
     * to standard output.  If the user cancels, or if an error occurs, then the current
     * output destination is not changed.
     */
    public static boolean writeUserSelectedFile() {
        if (fileDialog == null)
            fileDialog = new JFileChooser();
        fileDialog.setDialogTitle("Select File for Output");
        File selectedFile;
        while (true) {
            int option = fileDialog.showSaveDialog(null);
            if (option != JFileChooser.APPROVE_OPTION)
                return false;  // user canceled
            selectedFile = fileDialog.getSelectedFile();
            if (selectedFile.exists()) {
                int response = JOptionPane.showConfirmDialog(null,
                        "The file \"" + selectedFile.getName() + "\" already exists.  Do you want to replace it?",
                        "Replace existing file?",
                        JOptionPane.YES_NO_OPTION, JOptionPane.WARNING_MESSAGE);
                if (response == JOptionPane.YES_OPTION)
                    break;
            }
            else {
                break;
            }
        }
        PrintWriter newout;
        try {
            newout = new PrintWriter(new FileWriter(selectedFile));
        }
        catch (Exception e) {
            throw new IllegalArgumentException("Can't open file \"" + selectedFile.getName() + "\" for output.\n"
                             + "(Error :" + e + ")");
        }
        if (!writingStandardOutput) {
            try {
                out.close();
            }
            catch (Exception e) {
            }
        }
        out = newout;
        writingStandardOutput = false;
        outputFileName = selectedFile.getName();
        outputErrorCount = 0;
        return true;
    }
 

    /**
     * If TextIO is currently reading from a file, then the return value is the name of the file.
     * If the class is reading from standard input or from a stream, then the return value is null.
     */
    public static String getInputFileName() {
        return inputFileName;
    }
 

    /**
     * If TextIO is currently writing to a file, then the return value is the name of the file.
     * If the class is writing to standard output or to a stream, then the return value is null.
     */
    public static String getOutputFileName() {
        return outputFileName;
    }
 

    // *************************** Output Methods *********************************
     
    /**
     * Write a single value to the current output destination, using the default format
     * and no extra spaces.  This method will handle any type of parameter, even one
     * whose type is one of the primitive types.
     */
    public static void put(Object x) {
        out.print(x);
        out.flush();
        if (out.checkError())
            outputError("Error while writing output.");
    }
 
    /**
     * Write a single value to the current output destination, using the default format
     * and outputting at least minChars characters (with extra spaces added before the
     * output value if necessary).  This method will handle any type of parameter, even one
     * whose type is one of the primitive types.
     * @param x The value to be output, which can be of any type.
     * @param minChars The minimum number of characters to use for the output.  If x requires fewer
     * then this number of characters, then extra spaces are added to the front of x to bring
     * the total up to minChars.  If minChars is less than or equal to zero, then x will be printed
     * in the minimum number of spaces possible.
     */
    public static void put(Object x, int minChars)  {
        if (minChars <= 0)
            out.print(x);
        else
            out.printf("%" + minChars + "s", x);
        out.flush();
        if (out.checkError())
            outputError("Error while writing output.");
    }
     
    /**
     * This is equivalent to put(x), followed by an end-of-line.
     */
    public static void putln(Object x) {
        out.println(x);
        out.flush();
        if (out.checkError())
            outputError("Error while writing output.");
    }
 
    /**
     * This is equivalent to put(x,minChars), followed by an end-of-line.
     */
    public static void putln(Object x, int minChars) {
        put(x,minChars);
        out.println();
        out.flush();
        if (out.checkError())
            outputError("Error while writing output.");
    }

    /**
     * Write an end-of-line character to the current output destination.
     */
    public static void putln() {
        out.println();
        out.flush();
        if (out.checkError())
            outputError("Error while writing output.");
    }
 
    /**
     * Writes formatted output values to the current output destination.  This method has the
     * same function as System.out.printf(); the details of formatted output are not discussed
     * here.  The first parameter is a string that describes the format of the output.  There
     * can be any number of additional parameters; these specify the values to be output and
     * can be of any type.  This method will throw an IllegalArgumentException if the
     * format string is null or if the format string is illegal for the values that are being
     * output.
     */
    public static void putf(String format, Object... items) {
        if (format == null)
            throw new IllegalArgumentException("Null format string in TextIO.putf() method.");
        try {
            out.printf(format,items);
        }
        catch (IllegalFormatException e) {
            throw new IllegalArgumentException("Illegal format string in TextIO.putf() method.");
        }
        out.flush();
        if (out.checkError())
            outputError("Error while writing output.");
    }
 
    // *************************** Input Methods *********************************

    /**
     * Test whether the next character in the current input source is an end-of-line.  Note that
     * this method does NOT skip whitespace before testing for end-of-line -- if you want to do
     * that, call skipBlanks() first.
     */
    public static boolean eoln() {
        return peek() == '\n';
    }

    /**
     * Test whether the next character in the current input source is an end-of-file.  Note that
     * this method does NOT skip whitespace before testing for end-of-line -- if you want to do
     * that, call skipBlanks() or skipWhitespace() first.
     */
    public static boolean eof()  {
        return peek() == EOF;
    }
 
    /**
     * Reads the next character from the current input source.  The character can be a whitespace
     * character; compare this to the getChar() method, which skips over whitespace and returns the
     * next non-whitespace character.  An end-of-line is always returned as the character '\n', even
     * when the actual end-of-line in the input source is something else, such as '\r' or "\r\n".
     * This method will throw an IllegalArgumentException if the input is at end-of-file (which will
     * not ordinarily happen if reading from standard input).
     */
    public static char getAnyChar() {
        return readChar();
    }

    /**
     * Returns the next character in the current input source, without actually removing that
     * character from the input.  The character can be a whitespace character and can be the
     * end-of-file character (specified by the constant TextIO.EOF).An end-of-line is always returned
     * as the character '\n', even when the actual end-of-line in the input source is something else,
     * such as '\r' or "\r\n".  This method never causes an error.
     */
    public static char peek() {
        return lookChar();
    }
 
    /**
     * Skips over any whitespace characters, except for end-of-lines.  After this method is called,
     * the next input character is either an end-of-line, an end-of-file, or a non-whitespace character.
     * This method never causes an error.  (Ordinarily, end-of-file is not possible when reading from
     * standard input.)
     */
    public static void skipBlanks() {
        char ch=lookChar();
        while (ch != EOF && ch != '\n' && Character.isWhitespace(ch)) {
            readChar();
            ch = lookChar();
        }
    }

    /**
     * Skips over any whitespace characters, including for end-of-lines.  After this method is called,
     * the next input character is either an end-of-file or a non-whitespace character.
     * This method never causes an error. (Ordinarily, end-of-file is not possible when reading from
     * standard input.)
     */
    private static void skipWhitespace() {
        char ch=lookChar();
        while (ch != EOF && Character.isWhitespace(ch)) {
            readChar();
            if (ch == '\n' && readingStandardInput && writingStandardOutput) {
                out.print("? ");
                out.flush();
            }
            ch = lookChar();
        }
    }

    /**
     * Skips whitespace characters and then reads a value of type byte from input, discarding the rest of
     * the current line of input (including the next end-of-line character, if any).  When using standard IO,
     * this will not produce an error; the user will be prompted repeatedly for input until a legal value
     * is input.  In other cases, an IllegalArgumentException will be thrown if a legal value is not found.
     */
    public static byte getlnByte() {
        byte x=getByte();
        emptyBuffer();
        return x;
    }
 
    /**
     * Skips whitespace characters and then reads a value of type short from input, discarding the rest of
     * the current line of input (including the next end-of-line character, if any).  When using standard IO,
     * this will not produce an error; the user will be prompted repeatedly for input until a legal value
     * is input.  In other cases, an IllegalArgumentException will be thrown if a legal value is not found.
     */
    public static short getlnShort() {
        short x=getShort();
        emptyBuffer();
        return x;
    }
 
    /**
     * Skips whitespace characters and then reads a value of type int from input, discarding the rest of
     * the current line of input (including the next end-of-line character, if any).  When using standard IO,
     * this will not produce an error; the user will be prompted repeatedly for input until a legal value
     * is input.  In other cases, an IllegalArgumentException will be thrown if a legal value is not found.
     */
    public static int getlnInt() {
        int x=getInt();
        emptyBuffer();
        return x;
    }
 
    /**
     * Skips whitespace characters and then reads a value of type long from input, discarding the rest of
     * the current line of input (including the next end-of-line character, if any).  When using standard IO,
     * this will not produce an error; the user will be prompted repeatedly for input until a legal value
     * is input.  In other cases, an IllegalArgumentException will be thrown if a legal value is not found.
     */
    public static long getlnLong() {
        long x=getLong();
        emptyBuffer();
        return x;
    }
 
    /**
     * Skips whitespace characters and then reads a value of type float from input, discarding the rest of
     * the current line of input (including the next end-of-line character, if any).  When using standard IO,
     * this will not produce an error; the user will be prompted repeatedly for input until a legal value
     * is input.  In other cases, an IllegalArgumentException will be thrown if a legal value is not found.
     */
    public static float getlnFloat() {
        float x=getFloat();
        emptyBuffer();
        return x;
    }
 
    /**
     * Skips whitespace characters and then reads a value of type double from input, discarding the rest of
     * the current line of input (including the next end-of-line character, if any).  When using standard IO,
     * this will not produce an error; the user will be prompted repeatedly for input until a legal value
     * is input.  In other cases, an IllegalArgumentException will be thrown if a legal value is not found.
     */
    public static double getlnDouble() {
        double x=getDouble();
        emptyBuffer();
        return x;
    }
 
    /**
     * Skips whitespace characters and then reads a value of type char from input, discarding the rest of
     * the current line of input (including the next end-of-line character, if any).  Note that the value
     * that is returned will be a non-whitespace character; compare this with the getAnyChar() method.
     * When using standard IO, this will not produce an error.  In other cases, an error can occur if
     * an end-of-file is encountered.
     */
    public static char getlnChar() {
        char x=getChar();
        emptyBuffer();
        return x;
    }
 
    /**
     * Skips whitespace characters and then reads a value of type boolean from input, discarding the rest of
     * the current line of input (including the next end-of-line character, if any).  When using standard IO,
     * this will not produce an error; the user will be prompted repeatedly for input until a legal value
     * is input.  In other cases, an IllegalArgumentException will be thrown if a legal value is not found.
     * <p>Legal inputs for a boolean input are: true, t, yes, y, 1, false, f, no, n, and 0; letters can be
     * either upper case or lower case. One "word" of input is read, using the getWord() method, and it
     * must be one of these; note that the "word"  must be terminated by a whitespace character (or end-of-file).
     */
    public static boolean getlnBoolean() {
        boolean x=getBoolean();
        emptyBuffer();
        return x;
    }
 
    /**
     * Skips whitespace characters and then reads one "word" from input, discarding the rest of
     * the current line of input (including the next end-of-line character, if any).  A word is defined as
     * a sequence of non-whitespace characters (not just letters!).   When using standard IO,
     * this will not produce an error.  In other cases, an IllegalArgumentException will be thrown
     * if an end-of-file is encountered.
     */
    public static String getlnWord() {
        String x=getWord();
        emptyBuffer();
        return x;
    }
 
    /**
     * This is identical to getln().
     */
    public static String getlnString() {
        return getln();
    }
 
    /**
     * Reads all the characters from the current input source, up to the next end-of-line.  The end-of-line
     * is read but is not included in the return value.  Any other whitespace characters on the line are retained,
     * even if they occur at the start of input.  The return value will be an empty string if there are
     * no characters before the end-of-line.  When using standard IO, this will not produce an error.
     * In other cases, an IllegalArgumentException will be thrown if an end-of-file is encountered.
     */
    public static String getln() {
        StringBuffer s = new StringBuffer(100);
        char ch = readChar();
        while (ch != '\n') {
            s.append(ch);
            ch = readChar();
        }
        return s.toString();
    }
 
    /**
     * Skips whitespace characters and then reads a value of type byte from input.  Any additional characters on
     * the current line of input are retained, and will be read by the next input operation.  When using standard IO,
     * this will not produce an error; the user will be prompted repeatedly for input until a legal value
     * is input.  In other cases, an IllegalArgumentException will be thrown if a legal value is not found.
     */
    public static byte getByte()   {
        return (byte)readInteger(-128L,127L);
    }

    /**
     * Skips whitespace characters and then reads a value of type short from input.  Any additional characters on
     * the current line of input are retained, and will be read by the next input operation.  When using standard IO,
     * this will not produce an error; the user will be prompted repeatedly for input until a legal value
     * is input.  In other cases, an IllegalArgumentException will be thrown if a legal value is not found.
     */
    public static short getShort() {
        return (short)readInteger(-32768L,32767L);
    }
 
    /**
     * Skips whitespace characters and then reads a value of type int from input.  Any additional characters on
     * the current line of input are retained, and will be read by the next input operation.  When using standard IO,
     * this will not produce an error; the user will be prompted repeatedly for input until a legal value
     * is input.  In other cases, an IllegalArgumentException will be thrown if a legal value is not found.
     */
    public static int getInt()     {
        return (int)readInteger(Integer.MIN_VALUE, Integer.MAX_VALUE);
    }
 
    /**
     * Skips whitespace characters and then reads a value of type long from input.  Any additional characters on
     * the current line of input are retained, and will be read by the next input operation.  When using standard IO,
     * this will not produce an error; the user will be prompted repeatedly for input until a legal value
     * is input.  In other cases, an IllegalArgumentException will be thrown if a legal value is not found.
     */
    public static long getLong()   {
        return readInteger(Long.MIN_VALUE, Long.MAX_VALUE);
    }
 
    /**
     * Skips whitespace characters and then reads a single non-whitespace character from input.  Any additional characters on
     * the current line of input are retained, and will be read by the next input operation.  When using standard IO,
     * this will not produce an error.  In other cases, an IllegalArgumentException will be thrown if an end-of-file
     * is encountered.
     */
    public static char getChar() {
        skipWhitespace();
        return readChar();
    }
 
    /**
     * Skips whitespace characters and then reads a value of type float from input.  Any additional characters on
     * the current line of input are retained, and will be read by the next input operation.  When using standard IO,
     * this will not produce an error; the user will be prompted repeatedly for input until a legal value
     * is input.  In other cases, an IllegalArgumentException will be thrown if a legal value is not found.
     */
    public static float getFloat() {
        float x = 0.0F;
        while (true) {
            String str = readRealString();
            if (str == null) {
                errorMessage("Floating point number not found.",
                        "Real number in the range " + (-Float.MAX_VALUE) + " to " + Float.MAX_VALUE);
            }
            else {
                try {
                    x = Float.parseFloat(str);
                }
                catch (NumberFormatException e) {
                    errorMessage("Illegal floating point input, " + str + ".",
                            "Real number in the range " +  (-Float.MAX_VALUE) + " to " + Float.MAX_VALUE);
                    continue;
                }
                if (Float.isInfinite(x)) {
                    errorMessage("Floating point input outside of legal range, " + str + ".",
                            "Real number in the range " +  (-Float.MAX_VALUE) + " to " + Float.MAX_VALUE);
                    continue;
                }
                break;
            }
        }
        inputErrorCount = 0;
        return x;
    }
 
    /**
     * Skips whitespace characters and then reads a value of type double from input.  Any additional characters on
     * the current line of input are retained, and will be read by the next input operation.  When using standard IO,
     * this will not produce an error; the user will be prompted repeatedly for input until a legal value
     * is input.  In other cases, an IllegalArgumentException will be thrown if a legal value is not found.
     */
    public static double getDouble() {
        double x = 0.0;
        while (true) {
            String str = readRealString();
            if (str == null) {
                errorMessage("Floating point number not found.",
                        "Real number in the range " + (-Double.MAX_VALUE) + " to " + Double.MAX_VALUE);
            }
            else {
                try {
                    x = Double.parseDouble(str);
                }
                catch (NumberFormatException e) {
                    errorMessage("Illegal floating point input, " + str + ".",
                            "Real number in the range " + (-Double.MAX_VALUE) + " to " + Double.MAX_VALUE);
                    continue;
                }
                if (Double.isInfinite(x)) {
                    errorMessage("Floating point input outside of legal range, " + str + ".",
                            "Real number in the range " + (-Double.MAX_VALUE) + " to " + Double.MAX_VALUE);
                    continue;
                }
                break;
            }
        }
        inputErrorCount = 0;
        return x;
    }
 
    /**
     * Skips whitespace characters and then reads one "word" from input. Any additional characters on
     * the current line of input are retained, and will be read by the next input operation.  A word is defined as
     * a sequence of non-whitespace characters (not just letters!).   When using standard IO,
     * this will not produce an error.  In other cases, an IllegalArgumentException will be thrown
     * if an end-of-file is encountered.
     */
    public static String getWord() {
        skipWhitespace();
        StringBuffer str = new StringBuffer(50);
        char ch = lookChar();
        while (ch == EOF || !Character.isWhitespace(ch)) {
            str.append(readChar());
            ch = lookChar();
        }
        return str.toString();
    }
 
    /**
     * Skips whitespace characters and then reads a value of type boolean from input.  Any additional characters on
     * the current line of input are retained, and will be read by the next input operation.  When using standard IO,
     * this will not produce an error; the user will be prompted repeatedly for input until a legal value
     * is input.  In other cases, an IllegalArgumentException will be thrown if a legal value is not found.
     * <p>Legal inputs for a boolean input are: true, t, yes, y, 1, false, f, no, n, and 0; letters can be
     * either upper case or lower case. One "word" of input is read, using the getWord() method, and it
     * must be one of these; note that the "word"  must be terminated by a whitespace character (or end-of-file).
     */
    public static boolean getBoolean() {
        boolean ans = false;
        while (true) {
            String s = getWord();
            if ( s.equalsIgnoreCase("true") || s.equalsIgnoreCase("t") ||
                    s.equalsIgnoreCase("yes")  || s.equalsIgnoreCase("y") ||
                    s.equals("1") ) {
                ans = true;
                break;
            }
            else if ( s.equalsIgnoreCase("false") || s.equalsIgnoreCase("f") ||
                    s.equalsIgnoreCase("no")  || s.equalsIgnoreCase("n") ||
                    s.equals("0") ) {
                ans = false;
                break;
            }
            else
                errorMessage("Illegal boolean input value.",
                "one of:  true, false, t, f, yes, no, y, n, 0, or 1");
        }
        inputErrorCount = 0;
        return ans;
    }
 
    // ***************** Everything beyond this point is private implementation detail *******************
 
    private static String inputFileName;  // Name of file that is the current input source, or null if the source is not a file.
    private static String outputFileName; // Name of file that is the current output destination, or null if the destination is not a file.
 
    private static JFileChooser fileDialog; // Dialog used by readUserSelectedFile() and writeUserSelectedFile()
 
    private final static BufferedReader standardInput = new BufferedReader(new InputStreamReader(System.in));  // wraps standard input stream
    private final static PrintWriter standardOutput = new PrintWriter(System.out);  // wraps standard output stream

    private static BufferedReader in = standardInput;  // Stream that data is read from; the current input source.
    private static PrintWriter out = standardOutput;   // Stream that data is written to; the current output destination.
 
    private static boolean readingStandardInput = true;
    private static boolean writingStandardOutput = true;
 
    private static int inputErrorCount;  // Number of consecutive errors on standard input; reset to 0 when a successful read occurs.
    private static int outputErrorCount;  // Number of errors on standard output since it was selected as the output destination.
 
    private static Matcher integerMatcher;  // Used for reading integer numbers; created from the integer Regex Pattern.
    private static Matcher floatMatcher;   // Used for reading floating point numbers; created from the floatRegex Pattern.
    private final static Pattern integerRegex = Pattern.compile("(\\+|-)?[0-9]+");
    private final static Pattern floatRegex = Pattern.compile("(\\+|-)?(([0-9]+(\\.[0-9]*)?)|(\\.[0-9]+))((e|E)(\\+|-)?[0-9]+)?");
 
    private static String buffer = null;  // One line read from input.
    private static int pos = 0;           // Position of next char in input line that has not yet been processed.
 
    private static String readRealString() {   // read chars from input following syntax of real numbers
        skipWhitespace();
        if (lookChar() == EOF)
            return null;
        if (floatMatcher == null)
            floatMatcher = floatRegex.matcher(buffer);
        floatMatcher.region(pos,buffer.length());
        if (floatMatcher.lookingAt()) {
            String str = floatMatcher.group();
            pos = floatMatcher.end();
            return str;
        }
        else
            return null;
    }
 
    private static String readIntegerString() {  // read chars from input following syntax of integers
        skipWhitespace();
        if (lookChar() == EOF)
            return null;
        if (integerMatcher == null)
            integerMatcher = integerRegex.matcher(buffer);
        integerMatcher.region(pos,buffer.length());
        if (integerMatcher.lookingAt()) {
            String str = integerMatcher.group();
            pos = integerMatcher.end();
            return str;
        }
        else
            return null;
    }
 
    private static long readInteger(long min, long max) {  // read long integer, limited to specified range
        long x=0;
        while (true) {
            String s = readIntegerString();
            if (s == null){
                errorMessage("Integer value not found in input.",
                        "Integer in the range " + min + " to " + max);
            }
            else {
                String str = s.toString();
                try {
                    x = Long.parseLong(str);
                }
                catch (NumberFormatException e) {
                    errorMessage("Illegal integer input, " + str + ".",
                            "Integer in the range " + min + " to " + max);
                    continue;
                }
                if (x < min || x > max) {
                    errorMessage("Integer input outside of legal range, " + str + ".",
                            "Integer in the range " + min + " to " + max);
                    continue;
                }
                break;
            }
        }
        inputErrorCount = 0;
        return x;
    }
 
 
    private static void errorMessage(String message, String expecting) {  // Report error on input.
        if (readingStandardInput && writingStandardOutput) {
                // inform user of error and force user to re-enter.
            out.println();
            out.print("  *** Error in input: " + message + "\n");
            out.print("  *** Expecting: " + expecting + "\n");
            out.print("  *** Discarding Input: ");
            if (lookChar() == '\n')
                out.print("(end-of-line)\n\n");
            else {
                while (lookChar() != '\n')    // Discard and echo remaining chars on the current line of input.
                    out.print(readChar());
                out.print("\n\n");
            }
            out.print("Please re-enter: ");
            out.flush();
            readChar();  // discard the end-of-line character
            inputErrorCount++;
            if (inputErrorCount >= 10)
                throw new IllegalArgumentException("Too many input consecutive input errors on standard input.");
        }
        else if (inputFileName != null)
            throw new IllegalArgumentException("Error while reading from file \"" + inputFileName + "\":\n"
                    + message + "\nExpecting " + expecting);
        else
            throw new IllegalArgumentException("Error while reading from inptu stream:\n"
                    + message + "\nExpecting " + expecting);
    }
 
    private static char lookChar() {  // return next character from input
        if (buffer == null || pos > buffer.length())
            fillBuffer();
        if (buffer == null)
            return EOF;
        else if (pos == buffer.length())
            return '\n';
        else
            return buffer.charAt(pos);
    }
 
    private static char readChar() {  // return and discard next character from input
        char ch = lookChar();
        if (buffer == null) {
            if (readingStandardInput)
                throw new IllegalArgumentException("Attempt to read past end-of-file in standard input???");
            else
                throw new IllegalArgumentException("Attempt to read past end-of-file in file \"" + inputFileName + "\".");
        }
        pos++;
        return ch;
    }
     
    private static void fillBuffer() {    // Wait for user to type a line and press return,
        try {
            buffer = in.readLine();
        }
        catch (Exception e) {
            if (readingStandardInput)
                throw new IllegalArgumentException("Error while reading standard input???");
            else if (inputFileName != null)
                throw new IllegalArgumentException("Error while attempting to read from file \"" + inputFileName + "\".");
            else
                throw new IllegalArgumentException("Errow while attempting to read form an input stream.");
        }
        pos = 0;
        floatMatcher = null;
        integerMatcher = null;
    }
 
    private static void emptyBuffer() {   // discard the rest of the current line of input
        buffer = null;
    }
 
    private static void outputError(String message) {  // Report an error on output.
        if (writingStandardOutput) {
            System.err.println("Error occurred in TextIO while writing to standard output!!");
            outputErrorCount++;
            if (outputErrorCount >= 10) {
                outputErrorCount = 0;
                throw new IllegalArgumentException("Too many errors while writing to standard output.");
            }
        }
        else if (outputFileName != null){
            throw new IllegalArgumentException("Error occurred while writing to file \""
                    + outputFileName+ "\":\n   " + message);
        }
        else {
            throw new IllegalArgumentException("Error occurred while writing to output stream:\n   " + message);
        }
    }
     
} // end of class TextIO
File TextIO.java ini saya dapat dan dengan berterimakasih sekali kepada seorang Profesor David J. Eck dari Department of Mathematics and Computer Science Hobart and William Smith Colleges 300 Pulteney Street Geneva, New York 14456.
 Profesor David J. Eck

PROFESOR DAVID ECK menerima gelar Ph.D. Matematika di Brandeis University pada tahun 1980. Tesisnya, " Gauge-natural Bundles and Generalized Gauge Theories, was in the area of Differential Geometry". Setelah mengajar selama beberapa tahun di Dartmouth College dan Universitas Negeri New York di Buffalo, Eck bergabung dengan fakultas Hobart dan William Smith Colleges pada tahun 1986. Saat ini, sebagian besar program ia mengajar dalam ilmu komputer. proyek baru-baru ini termasuk menulis versi Java dari xFunctions, Program matematika populernya untuk Macintosh, dan pengantar pemrograman teks on-line . Prof David Eck telah menerbitkan buku, " The Most Complex Machine ", yang telah digunakan dalam kursus Ilmu Komputer 120: Prinsip Ilmu Komputer. Untuk informasi lebih lanjut dan untuk link ke pekerjaannya on-line, lihat Eck disini : http://math.hws.edu/eck/index.html
Dengan begitu, saat ini kita mempunya 1 packages file (periksa folder file kita pada subfolder src akan ada 2 file class java yakni CLASS BungaInvestasi4.java dan CLASS TextIO.java) dengan 2 class metode, sehingga file CLASS BungaInvestasi4, dapat dijalankan dan tidak lagi meninggalkan pesan ERROR, dan saat kita jalankan, akan menghasilkan output :
It's perfect !!!
Dengan CLASS TextIO.java file dari Prof David Eck tersebut, kita tidak perlu lagi membuat file serupa untuk dapat menyelesaikan beberapa Java Program sederhana, yang menggunakan CLASS TextIO() sebagai user input-nya kecuali jika kita memang ingin membuat Java Program sendiri dengan metode berbeda, maka kita harus mampu membuat CLASS TextIO.java file tersebut sendiri.

Kita lanjutkan dengan membuat Java Program yang mampu menerima input dari user, untuk membuat data profile seseorang dengan CLASS TextIO() dan menyimpan file yang sudah di input tersebut kedalam TXT File.
Berikut Source code Java Program-nya :
// @uthor CHRISTIANTO "GEMBLONG" DHARMA WIBOWO LEARN JAVA
package createprofile;
/**
 * membuat file bernama "profile.txt" yang berisi beberapa informasi
 * tentang pengguna.  Pengguna harus mengisi data yang dibutuhkan.
 * 
 */
public class Createprofile {
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
System.out.println("CHRISTIANTO 'GEMBLONG' DHARMA WIBOWO LEARN JAVA");
System.out.println("INPUT DATA MENGGUNAKAN CLASS TextIO()");
System.out.println("-------------------------------------");
        String name;     // Nama pengguna.
        String email;    // Email pengguna.
        double salary;   // Pendapatan pertahun.
        String spouse; // Nama pasangan pengguna.

        TextIO.putln("Be Informatics One!  Program Ini Akan Membuat");
        TextIO.putln("Profile Kamu, Jika Kamu Bersedia Menjawab Beberapa Pertanyaan");
        TextIO.putln("Pertanyaannya Adalah.");
        TextIO.putln();

        /* Gather responses from the user. */

        TextIO.put("Apakah Nama Mu                 ?     ");
        name = TextIO.getln();
        TextIO.put("Alamat Email Mu                ?     ");
        email = TextIO.getln();
        TextIO.put("Berapa Pendapatan Tahunan Kamu ? Rp. ");
        salary = TextIO.getlnDouble();
        TextIO.put("Nama Pasangan Mu               ?     ");
        spouse = TextIO.getln();

        /* Write the user's information to the file named profile.txt. */

        TextIO.writeFile("profile.txt");  // subsequent output goes to file
        TextIO.putln("Name:            " + name); 
        TextIO.putln("Email:           " + email);
        TextIO.putln("Spouse Name :    " + spouse);
        TextIO.putf( "Yearly Income:   $%,1.2f%n", salary);

        /* Print a final message to standard output. */

        TextIO.writeStandardOutput();
        TextIO.putln("Tampiasih.  Profile Mu Sudah Dicatat Di profile.txt.");

    }

}
Dan pasti CLASS TextIO() akan error sampai kita membuat class metode baru seperti TUGAS dan LATIHAN diatas, maka dari itu ulangi langkah membuat CLASS TextIO() dan Save All, maka error akan terkoreksi, karena sudah bisa di compile oleh Netbeans IDE, dan saat kita jalankan Java Programmnya, akan menghasilkan seperti ini di jendela output :
Dan karena file yang sudah dinput oleh pengguna di simpan dalam txt file, maka tampilan txt file-nya seperti ini :
Its Done !!! Terimakasih pada sumber : 



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