java - JButton 按钮未显示在扩展类的 JPanel 中

Question

作业扩展了我们之前的实验室，在那里我们制作了一个非常基本的计算器。我们应该添加一些按钮 pow、sqrt、pct 和 log。

我扩展了我的 BasicCalculator.java 文件，但没有添加我在新类中添加的按钮，但 setBackground 颜色工作得非常好。那么为什么没有添加以相同方法添加的按钮？

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

public class Calculator extends BasicCalculator
{
// Attributes
protected JButton pow, sqr, pct, log;
// Constructors
public Calculator()
{
    super();
}
// Methods
public void createModifiedUserInterface()
{
    try {
        UIManager.setLookAndFeel( UIManager.getCrossPlatformLookAndFeelClassName() );
    } 
    catch (Exception e) {
        e.printStackTrace();
    }

    createUserInterface();
    pow = new JButton("^");
    sqr = new JButton("sqr");
    pct = new JButton("pct");
    log = new JButton("log");

    keyPad.add(pow);
    keyPad.add(sqr);
    keyPad.add(log);
    keyPad.add(pct);

    displayBox.setHorizontalAlignment(displayBox.RIGHT);
    displayBox.setBackground(Color.YELLOW);

    clr.setBackground(Color.RED);
    com.setBackground(Color.GREEN);        
    b0.setBackground(Color.YELLOW);
    b1.setBackground(Color.YELLOW);
    b2.setBackground(Color.YELLOW);
    b3.setBackground(Color.YELLOW);
    b4.setBackground(Color.YELLOW);
    b5.setBackground(Color.YELLOW);
    b6.setBackground(Color.YELLOW);
    b7.setBackground(Color.YELLOW);
    b8.setBackground(Color.YELLOW);
    b9.setBackground(Color.YELLOW);
    bd.setBackground(Color.YELLOW);
    add.setBackground(Color.ORANGE);
    sub.setBackground(Color.ORANGE);
    mul.setBackground(Color.ORANGE);
    div.setBackground(Color.ORANGE);
    mod.setBackground(Color.ORANGE);
    pow.setBackground(Color.ORANGE);
    sqr.setBackground(Color.PINK);
    log.setBackground(Color.PINK);
    pct.setBackground(Color.PINK);

    pow.addActionListener(this);
    sqr.addActionListener(this);
    log.addActionListener(this);
    pct.addActionListener(this);
}

public void actionPerformed(ActionEvent e)
{
    displayBox.setBackground(Color.YELLOW);
    super.actionPerformed(e);
    if (e.getSource() == pow)
    {
        operator = '^';
        operand1 = new Double(displayBox.getText()).doubleValue();
        displayBox.setText("");
    }
    if (e.getSource() == sqr)
    {
        operand1 = new Double(displayBox.getText()).doubleValue();
        displayBox.setBackground(Color.GREEN);
        displayBox.setText(new Double(Math.sqrt(operand1)).toString());
    }
    if (e.getSource() == log)
    {
        operand1 = new Double(displayBox.getText()).doubleValue();
        displayBox.setBackground(Color.GREEN);
        displayBox.setText(new Double(Math.log(operand1)).toString());
    }
    if (e.getSource() == pct)
    {
        operand1 = new Double(displayBox.getText()).doubleValue();
        displayBox.setBackground(Color.GREEN);            
        displayBox.setText(new Double(operand1 * 100).toString());
    }
}

public void calculate()
{
    displayBox.setBackground(Color.GREEN);
    super. calculate();

    if (operator == '^')
    {
        displayBox.setText(new Double(Math.pow(operand1, operand2)).toString());
    }
}

public static void main(String[] args) 
{
    Calculator mine = new Calculator();
    mine.createModifiedUserInterface(); 
}

}

这是“BasicCalculator.java”文件中的代码，尽管它非常笨重。

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

public class BasicCalculator implements ActionListener
{
//attributes
protected double operand1, operand2;
protected char operator;
protected JFrame calWin;
protected JTextField displayBox;
protected JPanel keyPad;
protected JButton b0, b1, b2, b3, b4, b5, b6, b7, b8, b9, dot;
protected JButton add, sub, mul, div, mod, com, clr;

//constructors
public BasicCalculator() 
{
    clean();
}

//methods
public void clean()
{
    operand1 = 0;
    operand2 = 0;
    operator = ' ';

}

public void createUserInterface()
{
    calWin = new JFrame("Calculator");
    displayBox = new JTextField(20);
    keyPad = new JPanel();
    b0 = new JButton("0");
    b1 = new JButton("1");
    b2 = new JButton("2");
    b3 = new JButton("3");
    b4 = new JButton("4");
    b5 = new JButton("5");
    b6 = new JButton("6");
    b7 = new JButton("7");
    b8 = new JButton("8");
    b9 = new JButton("9");
    dot = new JButton(".");
    add = new JButton("+");
    sub = new JButton("-");
    mul = new JButton("*");
    div = new JButton("/");
    mod = new JButton("%");
    com = new JButton("=");
    clr = new JButton("C");

    keyPad.add(displayBox);
    keyPad.add(b0);
    keyPad.add(b1);
    keyPad.add(b2);
    keyPad.add(b3);
    keyPad.add(b4);
    keyPad.add(b5);
    keyPad.add(b6);
    keyPad.add(b7);
    keyPad.add(b8);
    keyPad.add(b9);
    keyPad.add(dot);
    keyPad.add(add);
    keyPad.add(sub);
    keyPad.add(mul);
    keyPad.add(div);
    keyPad.add(mod);
    keyPad.add(com);
    keyPad.add(clr);
    calWin.getContentPane().add(keyPad);
    calWin.setSize(300, 300);
    calWin.setVisible(true);
    calWin.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    b0.addActionListener(this);
    b1.addActionListener(this);
    b2.addActionListener(this);
    b3.addActionListener(this);
    b4.addActionListener(this);
    b5.addActionListener(this);
    b6.addActionListener(this);
    b7.addActionListener(this);
    b8.addActionListener(this);
    b9.addActionListener(this);
    dot.addActionListener(this);
    add.addActionListener(this);
    sub.addActionListener(this);
    mul.addActionListener(this);
    div.addActionListener(this);
    mod.addActionListener(this);
    com.addActionListener(this);
    clr.addActionListener(this);

}

public void actionPerformed(ActionEvent e)
{
    if(e.getSource() == b0)
    {
        if(displayBox.getText().contains("+") && operator == '+' || 
           displayBox.getText().contains("-") && operator == '-' || 
           displayBox.getText().contains("/") && operator == '/' || 
           displayBox.getText().contains("*") && operator == '*' || 
           displayBox.getText().contains("%") && operator == '%')
        {
            displayBox.setText("");
        }
        displayBox.setText(displayBox.getText() + "0");
    }
    if(e.getSource() == b1)
    {
        if(displayBox.getText().contains("+") && operator == '+' || 
           displayBox.getText().contains("-") && operator == '-' || 
           displayBox.getText().contains("/") && operator == '/' || 
           displayBox.getText().contains("*") && operator == '*' || 
           displayBox.getText().contains("%") && operator == '%')
        {
            displayBox.setText("");
        }
        displayBox.setText(displayBox.getText() + "1");
    }
    if(e.getSource() == b2)
    {
        if(displayBox.getText().contains("+") && operator == '+' || 
           displayBox.getText().contains("-") && operator == '-' || 
           displayBox.getText().contains("/") && operator == '/' || 
           displayBox.getText().contains("*") && operator == '*' || 
           displayBox.getText().contains("%") && operator == '%')
        {
            displayBox.setText("");
        }
        displayBox.setText(displayBox.getText() + "2");
    }
    if(e.getSource() == b3)
    {
        if(displayBox.getText().contains("+") && operator == '+' || 
           displayBox.getText().contains("-") && operator == '-' || 
           displayBox.getText().contains("/") && operator == '/' || 
           displayBox.getText().contains("*") && operator == '*' || 
           displayBox.getText().contains("%") && operator == '%')
        {
            displayBox.setText("");
        }
        displayBox.setText(displayBox.getText() + "3");
    }
    if(e.getSource() == b4)
    {
        if(displayBox.getText().contains("+") && operator == '+' || 
           displayBox.getText().contains("-") && operator == '-' || 
           displayBox.getText().contains("/") && operator == '/' || 
           displayBox.getText().contains("*") && operator == '*' || 
           displayBox.getText().contains("%") && operator == '%')
        {
            displayBox.setText("");
        }
        displayBox.setText(displayBox.getText() + "4");
    }
    if(e.getSource() == b5)
    {
        if(displayBox.getText().contains("+") && operator == '+' || 
           displayBox.getText().contains("-") && operator == '-' || 
           displayBox.getText().contains("/") && operator == '/' || 
           displayBox.getText().contains("*") && operator == '*' || 
           displayBox.getText().contains("%") && operator == '%')
        {
            displayBox.setText("");
        }
        displayBox.setText(displayBox.getText() + "5");
    }
    if(e.getSource() == b6)
    {
        if(displayBox.getText().contains("+") && operator == '+' || 
           displayBox.getText().contains("-") && operator == '-' || 
           displayBox.getText().contains("/") && operator == '/' || 
           displayBox.getText().contains("*") && operator == '*' || 
           displayBox.getText().contains("%") && operator == '%')
        {
            displayBox.setText("");
        }
        displayBox.setText(displayBox.getText() + "6");
    }
    if(e.getSource() == b7)
    {
        if(displayBox.getText().contains("+") && operator == '+' || 
           displayBox.getText().contains("-") && operator == '-' || 
           displayBox.getText().contains("/") && operator == '/' || 
           displayBox.getText().contains("*") && operator == '*' || 
           displayBox.getText().contains("%") && operator == '%')
        {
            displayBox.setText("");
        }
        displayBox.setText(displayBox.getText() + "7");
    }
    if(e.getSource() == b8)
    {
        if(displayBox.getText().contains("+") && operator == '+' || 
           displayBox.getText().contains("-") && operator == '-' || 
           displayBox.getText().contains("/") && operator == '/' || 
           displayBox.getText().contains("*") && operator == '*' || 
           displayBox.getText().contains("%") && operator == '%')
        {
            displayBox.setText("");
        }
        displayBox.setText(displayBox.getText() + "8");
    }
    if(e.getSource() == b9)
    {
        if(displayBox.getText().contains("+") && operator == '+' || 
           displayBox.getText().contains("-") && operator == '-' || 
           displayBox.getText().contains("/") && operator == '/' || 
           displayBox.getText().contains("*") && operator == '*' || 
           displayBox.getText().contains("%") && operator == '%')
        {
            displayBox.setText("");
        }
        displayBox.setText(displayBox.getText() + "9");
    }
    if(e.getSource() == dot)
    {
        if(displayBox.getText().contains("+") && operator == '+' || 
           displayBox.getText().contains("-") && operator == '-' || 
           displayBox.getText().contains("/") && operator == '/' || 
           displayBox.getText().contains("*") && operator == '*' || 
           displayBox.getText().contains("%") && operator == '%')
        {
            displayBox.setText("");
        }
        displayBox.setText(displayBox.getText() + ".");
    }
    if(e.getSource() == add)
    {
        operator = '+';
        operand1 = new Double(displayBox.getText()).doubleValue();
        displayBox.setText("+ ");
    }
            if(e.getSource() == sub)
    {
        if(displayBox.getText().trim().equals("") || 
           operator == '+' ||
           operator == '-' ||
           operator == '/' ||
           operator == '*' ||
           operator == '%')
        {
            displayBox.setText("-");
        }
        else
        {
            operator = '-';
            operand1 = new Double(displayBox.getText()).doubleValue();
            displayBox.setText("- ");
        }
    }
    if(e.getSource() == div)
    {
        operator = '/';
        operand1 = new Double(displayBox.getText()).doubleValue();
        displayBox.setText("/ ");
    }
    if(e.getSource() == mul)
    {
        operator = '*';
        operand1 = new Double(displayBox.getText()).doubleValue();
        displayBox.setText("* ");
    }
    if(e.getSource() == mod)
    {
        operator = '%';
        operand1 = new Double(displayBox.getText()).doubleValue();
        displayBox.setText("% ");
    }
    if(e.getSource() == clr)
    {
        displayBox.setText("");
        clean();
    }
    if(e.getSource() == com)
    {
        operand2 = new Double(displayBox.getText()).doubleValue();
        calculate();
    }
}

public void calculate()
{
    switch(operator)
    {
        case '+': displayBox.setText(new Double(operand1 + operand2).toString()); break;
        case '-': displayBox.setText(new Double(operand1 - operand2).toString()); break;    
        case '*': displayBox.setText(new Double(operand1 * operand2).toString()); break;  
        case '/': displayBox.setText(new Double(operand1 / operand2).toString()); break;   
        case '%': displayBox.setText(new Double(operand1 % operand2).toString()); break;    
    }
}

}

score 3 · Accepted Answer

使用更能满足您需求的布局管理器，例如GridLayout...

在此处输入图像描述

在您的BasicCalculator班级中，将更改keyPad为使用 aGridLayout并打包窗口。

keyPad = new JPanel(new GridLayout(0, 3));
//...
calWin.getContentPane().add(keyPad);

java - JButton 按钮未显示在扩展类的 JPanel 中

1 回答 1

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