如何使用 ActionListener 在我的计算器的文本区域中打印值

Question

我正在尝试使用 ActionListener 在我的计算器的文本区域中打印值，但我不明白为什么它不起作用

你能帮我解决这段代码吗，

我希望我能找到解决方案，因为我是 java 的初学者，非常感谢您的帮助

代码：

package calculator;

import javax.swing.SwingUtilities ;

public class Calculator {

public static void main(String[] args) {

    SwingUtilities.invokeLater(new Runnable(){


        public void run(){

        new frame();

        }

    });     

}

}

package calculator;

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame ;

public class frame extends JFrame{

    private TextPanel txt ;
    private KeyPanel key ;

    frame(){

        setVisible(true);
        setSize(300,500);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setName("Calc");

        setLayout(new BorderLayout());

        txt =new TextPanel();
        key =new KeyPanel();

        add(txt,BorderLayout.NORTH);
        add(key,BorderLayout.CENTER);

    }

}

package calculator;

import javax.swing.JPanel ;
import javax.swing.JTextArea ;
import java.awt.GridLayout;
import java.awt.BorderLayout ;
import java.awt.Font;
import javax.swing.JScrollPane;


public class TextPanel extends JPanel {

    private JTextArea textarea ;


        TextPanel(){

textarea= new JTextArea(5,5);      
textarea.append("0");

    setLayout(new BorderLayout());

        add(new JScrollPane(textarea),BorderLayout.NORTH);


    }

    public String getText(){

    return textarea.getText();

    }

    public void write(String text){

        textarea.append(text);

    }

}

package calculator;

import javax.swing.JButton ;
import java.awt.GridLayout ;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JPanel ;
public class KeyPanel extends JPanel /*implements ActionListener*/ {

private JButton b1,b2,b3,b4,b5,b6,b7,b8,b9,b10,b11,b12,b13,b14,b15,b16;
private TextPanel text ;

public KeyPanel(){

b1=new JButton("0");
b2=new JButton("1");
b3=new JButton("2");
b4=new JButton("3");
b5=new JButton("4");
b6=new JButton("5");
b7=new JButton("6");
b8=new JButton("7");
b9=new JButton("8");
b10=new JButton("9");
b11=new JButton("+");
b12=new JButton("-");
b13=new JButton("*");   
b14=new JButton("/");   
b15=new JButton("C");   
b16=new JButton("=");   


   setLayout(new GridLayout(5,5));

   add(b1,new GridLayout());
   add(b2,new GridLayout());
   add(b3,new GridLayout());
   add(b4,new GridLayout());
   add(b5,new GridLayout());
   add(b6,new GridLayout());
   add(b7,new GridLayout());
   add(b8,new GridLayout());
   add(b9,new GridLayout());
   add(b10,new GridLayout());
   add(b11,new GridLayout());
   add(b12,new GridLayout());
   add(b13,new GridLayout());
   add(b14,new GridLayout());
   add(b15,new GridLayout());
   add(b16,new GridLayout()); 

  }   
}

Answer 1

我支持@ControAltDel 的建议，跟随教程。您的程序设计不佳，显示出对 java 编程缺乏了解，但我想总有一天我们会成为新手。因此，这是您的解决方案的一种方法，我尝试遵循您的逻辑以免混淆更多，但是您可以研究和改进很多东西。例如按值传递变量，构建 GUI 的良好实践，java 接口。

package calculator;

import javax.swing.JButton;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JPanel;

public class KeyPanel extends JPanel  implements ActionListener {

    private JButton b1, b2, b3, b4, b5, b6, b7, b8, b9, b10, b11, b12, b13, b14, b15, b16;
    private TextPanel text;

    public KeyPanel(TextPanel text) {

        this.text = text;

        b1 = new JButton("0");

        b2 = new JButton("1");
        b3 = new JButton("2");
        b4 = new JButton("3");
        b5 = new JButton("4");
        b6 = new JButton("5");
        b7 = new JButton("6");
        b8 = new JButton("7");
        b9 = new JButton("8");
        b10 = new JButton("9");
        b11 = new JButton("+");
        b12 = new JButton("-");
        b13 = new JButton("*");
        b14 = new JButton("/");
        b15 = new JButton("C");
        b16 = new JButton("=");


        setLayout(new GridLayout(5, 5));

        add(b1, new GridLayout());
        add(b2, new GridLayout());
        add(b3, new GridLayout());
        add(b4, new GridLayout());
        add(b5, new GridLayout());
        add(b6, new GridLayout());
        add(b7, new GridLayout());
        add(b8, new GridLayout());
        add(b9, new GridLayout());
        add(b10, new GridLayout());
        add(b11, new GridLayout());
        add(b12, new GridLayout());
        add(b13, new GridLayout());
        add(b14, new GridLayout());
        add(b15, new GridLayout());
        add(b16, new GridLayout());

        b1.addActionListener(this);
        b2.addActionListener(this);
        b3.addActionListener(this);
        b4.addActionListener(this);
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        String face = e.getActionCommand();
        System.out.println(face + " was clicked");
        text.write(face);
    }
}

package calculator;

import java.awt.BorderLayout;

import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;

public class TextPanel extends JPanel {

    private JTextArea textarea;

    TextPanel() {
        textarea = new JTextArea(5, 5);
        textarea.append("0");
        setLayout(new BorderLayout());
        add(new JScrollPane(textarea), BorderLayout.NORTH);
        textarea.setEditable(false);
    }

    public String getText() {
        return textarea.getText();
    }

    public void write(String text) {
        textarea.setText(text);
    }

}

package calculator;

import java.awt.BorderLayout;

import javax.swing.JFrame;

public class frame extends JFrame {

    private TextPanel txt;
    private KeyPanel key;

    frame() {
        setVisible(true);
        setSize(300, 500);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setName("Calc");

        setLayout(new BorderLayout());

        txt = new TextPanel();
        key = new KeyPanel(txt);

        add(txt, BorderLayout.NORTH);
        add(key, BorderLayout.CENTER);

    }

}

如何使用 ActionListener 在我的计算器的文本区域中打印值

how to use ActionListener to print values in the textarea in my calculator

java

swing

calculator

actionlistener