在JAVA中將數據寫入.txt文件？

我想知道是否在JAVA中將計算的數據寫入文本文件。我的JAVA代碼是一個基於GUI的gpa計算器。我只想添加一個JButton & ActionListener，它將把類名，GPA點和計算的GPA寫入.txt文件。在JAVA中將數據寫入.txt文件？

這是我的JFrame驅動代碼：

import javax.swing.JFrame; 

public class Driver00 

{ 

    public static void main(String[] args) 

    { 
    /* 
    * Create a frame (outside box) and write what text 
    * will be displayed as the frame title 
    */ 
    JFrame frame = new JFrame("PHILIP MCQUITTY"); 

    // give frame a size 
    frame.setSize(520, 375); 

    // set location on the computer screen will frame appear 
    frame.setLocation(400, 166); 

    // use this so when you press X in corner, frame will close 
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 

    // Add your panel to the frame. name must match Panel class name 
    frame.setContentPane(new GpaCalc()); 

    // frame.setResizable(false); 

    // always include 
    frame.setVisible(true); 
    } 
}

這是我的JPanel代碼：

import javax.swing.*; 
import java.awt.*; 
import java.awt.event.*; 

public class GpaCalc extends JPanel { 
    private JLabel GPALabel, c1, c2, c3, c4, c5, c6, c7, g1, g2, g3, g4, g5, g6, g7; 
    private JTextField Class1, Class2, Class3, Class4, Class5, Class6, Class7, Grade1, Grade2, Grade3, Grade4, Grade5, Grade6, Grade7; 
    private double GPA1, GPA2, GPA3, GPA4, GPA5, GPA6, GPA7, GPA, BigDec; 

    public GpaCalc() { 
    setLayout(new FlowLayout()); 

    // Class Labels 
    GPALabel = new JLabel("0.00000000000000"); 
    GPALabel.setFont(new Font("Times New Roman", Font.BOLD, 60)); 
    GPALabel.setForeground(Color.red); 

    c1 = new JLabel("Block 1"); 
    c1.setFont(new Font("Times New Roman", Font.BOLD, 20)); 
    c1.setForeground(Color.black); 

    c2 = new JLabel("Block 2"); 
    c2.setFont(new Font("Times New Roman", Font.BOLD, 20)); 
    c2.setForeground(Color.black); 

    c3 = new JLabel("Block 3"); 
    c3.setFont(new Font("Times New Roman", Font.BOLD, 20)); 
    c3.setForeground(Color.black); 

    c4 = new JLabel("Block 4"); 
    c4.setFont(new Font("Times New Roman", Font.BOLD, 20)); 
    c4.setForeground(Color.black); 

    c5 = new JLabel("Block 5"); 
    c5.setFont(new Font("Times New Roman", Font.BOLD, 20)); 
    c5.setForeground(Color.black); 

    c6 = new JLabel("Block 6"); 
    c6.setFont(new Font("Times New Roman", Font.BOLD, 20)); 
    c6.setForeground(Color.black); 

    c7 = new JLabel("Block 7"); 
    c7.setFont(new Font("Times New Roman", Font.BOLD, 20)); 
    c7.setForeground(Color.black); 

    // Grade Labels 
    g1 = new JLabel("GPA Points"); 
    g1.setFont(new Font("Times New Roman", Font.BOLD, 20)); 
    g1.setForeground(Color.black); 

    g2 = new JLabel("GPA Points"); 
    g2.setFont(new Font("Times New Roman", Font.BOLD, 20)); 
    g2.setForeground(Color.black); 

    g3 = new JLabel("GPA Points"); 
    g3.setFont(new Font("Times New Roman", Font.BOLD, 20)); 
    g3.setForeground(Color.black); 

    g4 = new JLabel("GPA Points"); 
    g4.setFont(new Font("Times New Roman", Font.BOLD, 20)); 
    g4.setForeground(Color.black); 

    g5 = new JLabel("GPA Points"); 
    g5.setFont(new Font("Times New Roman", Font.BOLD, 20)); 
    g5.setForeground(Color.black); 

    g6 = new JLabel("GPA Points"); 
    g6.setFont(new Font("Times New Roman", Font.BOLD, 20)); 
    g6.setForeground(Color.black); 

    g7 = new JLabel("GPA Points"); 
    g7.setFont(new Font("Times New Roman", Font.BOLD, 20)); 
    g7.setForeground(Color.black); 

    // Class Textfields 
    Class1 = new JTextField("Enter Class Name", 10); 
    Class1.setHorizontalAlignment(SwingConstants.CENTER); 

    Class2 = new JTextField("Enter Class Name", 10); 
    Class2.setHorizontalAlignment(SwingConstants.CENTER); 

    Class3 = new JTextField("Enter Class Name", 10); 
    Class3.setHorizontalAlignment(SwingConstants.CENTER); 

    Class4 = new JTextField("Enter Class Name", 10); 
    Class4.setHorizontalAlignment(SwingConstants.CENTER); 

    Class5 = new JTextField("Enter Class Name", 10); 
    Class5.setHorizontalAlignment(SwingConstants.CENTER); 

    Class6 = new JTextField("Enter Class Name", 10); 
    Class6.setHorizontalAlignment(SwingConstants.CENTER); 

    Class7 = new JTextField("Enter Class Name", 10); 
    Class7.setHorizontalAlignment(SwingConstants.CENTER); 

    // Grade Textfields 
    Grade1 = new JTextField("0.0", 10); 
    Grade1.setHorizontalAlignment(SwingConstants.CENTER); 

    Grade2 = new JTextField("0.0", 10); 
    Grade2.setHorizontalAlignment(SwingConstants.CENTER); 

    Grade3 = new JTextField("0.0", 10); 
    Grade3.setHorizontalAlignment(SwingConstants.CENTER); 

    Grade4 = new JTextField("0.0", 10); 
    Grade4.setHorizontalAlignment(SwingConstants.CENTER); 

    Grade5 = new JTextField("0.0", 10); 
    Grade5.setHorizontalAlignment(SwingConstants.CENTER); 

    Grade6 = new JTextField("0.0", 10); 
    Grade6.setHorizontalAlignment(SwingConstants.CENTER); 

    Grade7 = new JTextField("0.0", 10); 
    Grade7.setHorizontalAlignment(SwingConstants.CENTER); 

    // Button(s) 
    JButton Calculate = new JButton("Calculate"); 
    Calculate.addActionListener(new Listener()); 

    JButton Reset = new JButton("Reset Fields"); 
    Reset.addActionListener(new Listener2()); 

    // Add(s) 
    add(GPALabel); 
    add(c1); 
    add(Class1); 
    add(Grade1); 
    add(g1); 
    add(c2); 
    add(Class2); 
    add(Grade2); 
    add(g2); 
    add(c3); 
    add(Class3); 
    add(Grade3); 
    add(g3); 
    add(c4); 
    add(Class4); 
    add(Grade4); 
    add(g4); 
    add(c5); 
    add(Class5); 
    add(Grade5); 
    add(g5); 
    add(c6); 
    add(Class6); 
    add(Grade6); 
    add(g6); 
    add(c7); 
    add(Class7); 
    add(Grade7); 
    add(g7); 
    add(Calculate); 
    add(Reset); 
    } 

    // Action Listener(s) 
    private class Listener implements ActionListener { 
    public void actionPerformed(ActionEvent e) { 

     GPA1 = Double.parseDouble(Grade1.getText()); 
     GPA2 = Double.parseDouble(Grade2.getText()); 
     GPA3 = Double.parseDouble(Grade3.getText()); 
     GPA4 = Double.parseDouble(Grade4.getText()); 
     GPA5 = Double.parseDouble(Grade5.getText()); 
     GPA6 = Double.parseDouble(Grade6.getText()); 
     GPA7 = Double.parseDouble(Grade7.getText()); 

     GPA = (GPA1 + GPA2 + GPA3 + GPA4 + GPA5 + GPA6 + GPA7)/7; 

     GPALabel.setText("" + GPA); 

    } 

    } 

    private class Listener2 implements ActionListener { 
    public void actionPerformed(ActionEvent e) { 

     Class1.setText("Enter Class Name"); 
     Class2.setText("Enter Class Name"); 
     Class3.setText("Enter Class Name"); 
     Class4.setText("Enter Class Name"); 
     Class5.setText("Enter Class Name"); 
     Class6.setText("Enter Class Name"); 
     Class7.setText("Enter Class Name"); 

     Grade1.setText("0.0"); 
     Grade2.setText("0.0"); 
     Grade3.setText("0.0"); 
     Grade4.setText("0.0"); 
     Grade5.setText("0.0"); 
     Grade6.setText("0.0"); 
     Grade7.setText("0.0"); 

     GPALabel.setText("0.00000000000000"); 

    } 

    } 

}

來源

2011-03-20 Philip McQuitty

檢查java I/O api。以下是將數據寫入文件的示例。

BufferedWriter writer = null; 
    try { 
     writer = new BufferedWriter(new FileWriter("./output.txt")); 
     writer.write("your data here"); 
    } catch (IOException e) { 
     System.err.println(e); 
    } finally { 
     if (writer != null) { 
      try { 
       writer.close(); 
      } catch (IOException e) { 
       System.err.println(e); 
      } 
     } 
    }

來源

2011-03-20 04:35:20

PrintWriter的PW =的新PrintWriter（新的FileWriter（「C：\\ output.txt的」） ;

pw.println（「的值是：」 + X）;

pw.close（）;

來源

2011-03-20 03:58:13 MeBigFatGuy

非常感謝快速回復！ JGrasp在第一個「;」之前給我一個解析錯誤。我已經添加了java.io import語句。我應該修復什麼？ – 2011-03-20 17:14:36

import java.io.*; 
class code{ 
public static void main(String args[]){ 
    try{ 
File r = new File("C:\\hello.txt"); 
    FileWriter pw = new FileWriter(r); 
PrintWriter pr = new PrintWriter(pw); 
pr.println("Hello world"); 
}catch(IOException e){} 
} 
}

來源

2013-08-05 06:45:59 chirath

在JAVA中將數據寫入.txt文件？

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