java从JTextField中获取文本并将其放入JTextArea中

Question

这是我的主课

public class Main {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
            Program p = new Program();
        }

}

这是我的课程

public class Program {

    public Program(){
        //System.out.println("Let's begin...");

        TextEditor textEditor = new TextEditor();
        textEditor.setVisible(true);
        textEditor.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);


    }
}

这是我的TextEditor类。在这个类中，我有一个JFrame，它有一个文本字段，我希望将计算器类中的华氏温度到celcus的转换结果放在其中

public class TextEditor extends JFrame implements ActionListener{
JTextArea textArea;

public TextEditor(){
    super("TextMe");
    this.setLayout(new BorderLayout());
    loadMenuBar();
    loadToolBar();
    loadTextArea();
    this.pack();
}

private void loadTextArea() {
    // TODO Auto-generated method stub
    textArea = new JTextArea();
    textArea.setPreferredSize(new Dimension(800,600));
    this.add(BorderLayout.CENTER, textArea);
}

    @Override
    public void actionPerformed(ActionEvent e) {
}   loadCalculator()
private void loadCalculator() {
    // TODO Auto-generated method stub
    Calculator c = new Calculator();
    Calculator calculator = new Calculator();
    calculator.setVisible(true);
    calculator.setDefaultCloseOperation(JFrame.HIDE_ON_CLOSE);

    textArea.setText(String.valueOf(c.fahrenheit));

}

这是我的计算器类，它扩展了JFrame并实现了ActionListener。在这里，JFrame会出现一个JButton，旁边有一个JTextField。当用户在文本字段中输入一个数字时，它会进行计算并将华氏温度转换为摄氏温度。完成后，我希望结果显示在TextEditor类的JTextArea上

public class Calculator extends JFrame implements ActionListener{
JButton fToCButton;
JTextField fToC;
double fahrenheit;
TextEditor a = new TextEditor();

public Calculator(){
            super("Unit Converter");
            this.setLayout(new FlowLayout());

            fToC = new JTextField(5);

fToCButton = new JButton("Ferenheit To Celcius");
            fToCButton.addActionListener(this);

add(fToCButton, BorderLayout.WEST);
            add(fToC);
this.pack()

@Override
        public void actionPerformed(ActionEvent e) {
            // TODO Auto-generated method stub
            if(e.getSource() == fToCButton){
                degreeConversion();
            }
        }

        private void degreeConversion() {
            // TODO Auto-generated method stub
            double conversion = Double.parseDouble(fToC.getText());
            fahrenheit = (((conversion -32) * 5) / 9);
            a.textArea.setText(String.valueOf(fahrenheit));
            System.out.println(fahrenheit);
        }


 }

Answer 1

正如Andrew Thompson已经指出的，确保您的代码至少可以编译并且有一个main方法。您提供的TextEditor类缺少loadMenuBar&loadToolBar方法actionPerformed&loadCalculator方法在某种程度上被合并在一起，两个类中都缺少一个主方法。请尽可能地阐述你的问题，以得到好的答案

我认为转换结果没有出现的原因是TextEditor和Calculator对象之间没有连接。在Calculator.degreeConversion方法中，您试图将结果传递给TextEditor对象，但该对象是由计算器本身创建的（请参见字段声明），并且该文本编辑器不可见。这可以通过将文本编辑器的引用传递给计算器构造函数来解决

代码：

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JTextArea;
import javax.swing.JTextField;


/**
 * TextEditor class.
 */
public class TextEditorVersion2 extends JFrame implements ActionListener {
    JTextArea textArea;

    public static void main(String[] args) {
        final TextEditorVersion2 textEditor = new TextEditorVersion2();
        textEditor.setVisible(true);
        final CalculatorVersion2 calculatorVersion2 = new CalculatorVersion2(textEditor);
        calculatorVersion2.setVisible(true);
    }

    public TextEditorVersion2(){
        super("TextMe");
        this.setLayout(new BorderLayout());
        // Freek: these methods are missing.
        //loadMenuBar();
        //loadToolBar();
        // Freek: these methods are missing.
        loadTextArea();
        this.pack();
    }

    private void loadTextArea() {
        // TODO Auto-generated method stub
        textArea = new JTextArea();
        textArea.setPreferredSize(new Dimension(800,600));
        this.add(BorderLayout.CENTER, textArea);
    }

    @Override
    public void actionPerformed(ActionEvent e) {
    }

    private void loadCalculator() {
        // TODO Auto-generated method stub
        CalculatorVersion2 c = new CalculatorVersion2(this);
        CalculatorVersion2 calculatorVersion2 = new CalculatorVersion2(this);
        calculatorVersion2.setVisible(true);
        calculatorVersion2.setDefaultCloseOperation(JFrame.HIDE_ON_CLOSE);

        textArea.setText(String.valueOf(c.fahrenheit));
    }
}


/**
 * Calculator class.
 */
class CalculatorVersion2 extends JFrame implements ActionListener {
    JButton fToCButton;
    JTextField fToC;
    double fahrenheit;
    TextEditorVersion2 a;

    public CalculatorVersion2(final TextEditorVersion2 textEditor) {
        super("Unit Converter");
        this.a = textEditor;
        this.setLayout(new FlowLayout());

        fToC = new JTextField(5);

        fToCButton = new JButton("Ferenheit To Celcius");
        fToCButton.addActionListener(this);

        add(fToCButton, BorderLayout.WEST);
        add(fToC);
        this.pack();
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        // TODO Auto-generated method stub
        if(e.getSource() == fToCButton){
            degreeConversion();
        }
    }

    private void degreeConversion() {
        // TODO Auto-generated method stub
        double conversion = Double.parseDouble(fToC.getText());
        fahrenheit = (((conversion -32) * 5) / 9);
        a.textArea.setText(String.valueOf(fahrenheit));
        System.out.println(fahrenheit);
    }
}