我如何在一个JFrame中添加两个扩展JPanel的类

Question

I created two class that extends JPanel and want to add that two class in one Frame. But i am unable to do it. Anyone help please.

my classes are -->

import java.awt.GridLayout;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class CalButton extends JPanel {
    private JButton[] buttons;
    private static final String[] buttonNames = { "7", "8", "9", "/", "4", "5",
            "6", "*", "1", "2", "3", "-", "0", ".", "=", "+" };
    private JPanel buttonPanel;

    public CalButton() {
        // TODO Auto-generated constructor stub
        buttons = new JButton[buttonNames.length];
        buttonPanel = new JPanel();
        buttonPanel.setLayout(new GridLayout(4, 4, 3, 3));

        for(int i=0; i<buttonNames.length; i++){
            buttons[i] = new JButton(buttonNames[i]);
            buttonPanel.add(buttons[i]);

        }
    }
}

Another Class-->

import java.awt.GridLayout;

import javax.swing.JPanel;
import javax.swing.JTextField;

public class CalField extends JPanel {
    private JPanel panelField;
    private JTextField field;

    public CalField() {
        // TODO Auto-generated constructor stub
        panelField = new JPanel();
        panelField.setLayout(new GridLayout(1, 1,5,5));
        field = new JTextField(20);
        panelField.add(field);

    }
}

Main class-->

public class Calculator {
    public static void main(String[] args) {

        JFrame application = new JFrame("Calculator");
        CalField calField = new CalField();
        CalButton calButton = new CalButton();
        application.setLayout(new GridLayout(2, 1));

        application.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        application.setSize(400, 450);
        application.setVisible(true);
    }
}

Anyone kindly solve this problem please. i'm stuck with this problem.

Answer 1

public CalButton() {
    // TODO Auto-generated constructor stub
    buttons = new JButton[buttonNames.length];
    buttonPanel = new JPanel();
    buttonPanel.setLayout(new GridLayout(4, 4, 3, 3));

    for(int i=0; i<buttonNames.length; i++){
        buttons[i] = new JButton(buttonNames[i]);
        buttonPanel.add(buttons[i]);

    }
}

The CalButton class already "is a" JPanel because you extend JPanel so there is no need to create another JPanel. Just add your buttons to the class:

public CalButton() {
    // TODO Auto-generated constructor stub
    buttons = new JButton[buttonNames.length];
    //buttonPanel = new JPanel();
    //buttonPanel.setLayout(new GridLayout(4, 4, 3, 3));
    setLayout(new GridLayout(4, 4, 3, 3));

    for(int i=0; i<buttonNames.length; i++){
        buttons[i] = new JButton(buttonNames[i]);
        //buttonPanel.add(buttons[i]);
        add(buttons[i]);
    }
}

Same with your CalcField class except in this case you probably don't need to set the layout manager. You can probably use the default FlowLayout.

Then the second problem is that you never add these panels to the frame:

    CalField calField = new CalField();
    CalButton calButton = new CalButton();
    //application.setLayout(new GridLayout(2, 1));
    application.add(calField, BorderLayout.PAGE_START);
    application.add(calButton, BorderLayout.CENTER);