Question

我目前正在从事一个简单的计算器项目，我发现自己遇到了一个小问题。我无法使用按钮在文本字段上书写。我希望能够使用框架上的按钮在文本上书写。

有人可以帮帮我吗？

这是我的代码：

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


public class Calculator extends JFrame{
JPanel NumberPanel = new JPanel();
String [] ButtonString = {"7","8","9","4","5","6","1","2","3","0",".","+/-"};
JButton ButtonArray [] = new JButton[ButtonString.length];
JPanel OperationPanel = new JPanel();
String [] OperationString = {"Erase","Ac","*","/","+","-","Ans","="};
JButton [] OperationArray = new JButton [OperationString.length];
Calculator(){

    for (int a = 0 ; a < ButtonArray.length ; a++){
        ButtonArray[a]= new JButton (ButtonString[a]);
    }
    NumberPanel.setLayout(new GridLayout(4,3,5,5));
    for (int a = 0 ; a < ButtonArray.length ; a++){
        NumberPanel.add(ButtonArray[a]);
    }

    for (int a = 0 ; a < OperationArray.length ; a++){
        OperationArray[a]= new JButton(OperationString[a]);
    }
    OperationPanel.setLayout(new GridLayout(4,2,5,5));
    for (int a = 0 ; a < OperationArray.length ; a++){
        OperationPanel.add(OperationArray[a]);
    }

    JPanel Finalpanel = new JPanel();
    Finalpanel.setLayout(new FlowLayout());
    Finalpanel.add(NumberPanel);Finalpanel.add(OperationPanel);

    JTextField WritingZone = new JTextField(27);
    WritingZone.setComponentOrientation(ComponentOrientation.RIGHT_TO_LEFT);
    WritingZone.setBorder(BorderFactory.createLoweredSoftBevelBorder());
    WritingZone.setEditable(false);
    JPanel TextPanel = new JPanel();
    TextPanel.add(WritingZone);


    JPanel AllPanel = new JPanel();
    AllPanel.setLayout(new BorderLayout(5,5));
    AllPanel.add(BorderLayout.NORTH, TextPanel);
    AllPanel.add(BorderLayout.CENTER, Finalpanel);
    AllPanel.setBorder(BorderFactory.createTitledBorder("Simple Calculator"));
    add(AllPanel);
}
public static void main (String [] arg){
    JFrame frame = new Calculator();
    frame.setVisible(true);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setLocationRelativeTo(null);
    frame.setSize(400,250);
    frame.setResizable(false);

}
}

Answer 1

首先，遵循Java命名约定。变量名称不应以大写字符开头。我从未在论坛中发布过这样的教程，教科书或示例，因此不要编写自己的约定。通过实例学习。

如果您希望按钮执行某些操作，则需要在按钮上添加ActionListener。或者更好的是创建一个可以通过按钮和键盘共享的Action，以便您可以使用键绑定。

简单示例：

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

public class CalculatorPanel extends JPanel
{
    private JTextField display;

    public CalculatorPanel()
    {
        Action numberAction = new AbstractAction()
        {
            @Override
            public void actionPerformed(ActionEvent e)
            {
                display.setCaretPosition( display.getDocument().getLength() );
                display.replaceSelection(e.getActionCommand());
            }
        };

        setLayout( new BorderLayout() );

        display = new JTextField();
        display.setEditable( false );
        display.setHorizontalAlignment(JTextField.RIGHT);
        add(display, BorderLayout.NORTH);

        JPanel buttonPanel = new JPanel();
        buttonPanel.setLayout( new GridLayout(0, 5) );
        add(buttonPanel, BorderLayout.CENTER);

        for (int i = 0; i < 10; i++)
        {
            String text = String.valueOf(i);
            JButton button = new JButton( text );
            button.addActionListener( numberAction );
            button.setBorder( new LineBorder(Color.BLACK) );
            button.setPreferredSize( new Dimension(50, 50) );
            buttonPanel.add( button );

            InputMap inputMap = button.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);
            inputMap.put(KeyStroke.getKeyStroke(text), text);
            inputMap.put(KeyStroke.getKeyStroke("NUMPAD" + text), text);
            button.getActionMap().put(text, numberAction);
        }
    }

    private static void createAndShowUI()
    {
//      UIManager.put("Button.margin", new Insets(10, 10, 10, 10) );

        JFrame frame = new JFrame("Calculator Panel");
        frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
        frame.add( new CalculatorPanel() );
        frame.pack();
        frame.setLocationRelativeTo( null );
        frame.setVisible(true);
    }

    public static void main(String[] args)
    {
        EventQueue.invokeLater(new Runnable()
        {
            public void run()
            {
                createAndShowUI();
            }
        });
    }
}

Answer 2

实施ActionPerformed方法。

  @Override
   public void ActionPerformed(ActionEvent e){
        JButton btn = (JButton)e.getSource();
        if(btn == btnName){
           String state = WritingZone.getText();
            WritingZone.setText(state+btnNum(operation));
        } else if(btn==otherButton)...
   }

- 然后将侦听器添加到每个按钮。 btn.addListener（本）;

- 这是一种方法。

Answer 3

你需要一个actionlistener ..

我编辑了你的代码，以便按钮1可以工作。

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


public class Calculator extends JFrame{

JPanel NumberPanel = new JPanel();

ButtonHandler handler = new ButtonHandler();
    JButton button;

JTextArea textArea;
Calculator(){

JPanel AllPanel = new JPanel();

AllPanel.setBorder(BorderFactory.createTitledBorder("Simple Calculator"));
getContentPane().add(AllPanel);
AllPanel.setLayout(null);

button = new JButton("1");
button.setBounds(10, 129, 89, 23);
button.addActionListener(handler);
AllPanel.add(button);

JButton button_1 = new JButton("2");
button_1.setBounds(109, 129, 89, 23);
AllPanel.add(button_1);

JButton button_2 = new JButton("3");
button_2.setBounds(208, 129, 89, 23);
AllPanel.add(button_2);

JButton button_3 = new JButton("4");
button_3.setBounds(10, 95, 89, 23);
AllPanel.add(button_3);

JButton button_4 = new JButton("5");
button_4.setBounds(109, 95, 89, 23);
AllPanel.add(button_4);

JButton button_5 = new JButton("6");
button_5.setBounds(208, 95, 89, 23);
AllPanel.add(button_5);

JButton button_6 = new JButton("7");
button_6.setBounds(10, 61, 89, 23);
AllPanel.add(button_6);

JButton button_7 = new JButton("8");
button_7.setBounds(109, 61, 89, 23);
AllPanel.add(button_7);

JButton button_8 = new JButton("9");
button_8.setBounds(208, 61, 89, 23);
AllPanel.add(button_8);

JButton button_9 = new JButton("0");
button_9.setBounds(109, 163, 89, 23);
AllPanel.add(button_9);

JButton btnClear = new JButton("Clear");
btnClear.setBounds(298, 163, 89, 23);
AllPanel.add(btnClear);

JButton btnAdd = new JButton("Add");
btnAdd.setBounds(298, 129, 89, 23);
AllPanel.add(btnAdd);

JButton btnSub = new JButton("Sub");
btnSub.setBounds(298, 95, 89, 23);
AllPanel.add(btnSub);

textArea = new JTextArea();
textArea.setBounds(43, 29, 253, 22);
AllPanel.add(textArea);
}

private class ButtonHandler implements ActionListener 
{
    public void actionPerformed (ActionEvent e)
    {
        if (e.getSource() == button)
        {
            textArea.insert("1",0);
        }
    }
}
public static void main (String [] arg){
    JFrame frame = new Calculator();
    frame.setVisible(true);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setLocationRelativeTo(null);
    frame.setSize(400,250);
    frame.setResizable(false);

}
}

如何使用JFrame上的JButtons在JTextField上编写？

3 个答案: