java - 调整 JPanel 的大小，以获取在最大化屏幕时使用 GridBagConstraints 的 GridBagLayout

Question

我需要在代码中更改什么，以便当我最大化窗口时，按钮将按比例展开？

当我运行程序时，它以我选择的大小开始，但我想使用最大化... 谢谢。

import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Insets;

import javax.swing.JTextField;
import javax.swing.JFrame;
import javax.swing.JButton;
import javax.swing.JPanel;
import javax.swing.BorderFactory;
import javax.swing.WindowConstants;

public class Calculator extends JFrame
{

    protected JTextField display;

    protected JButton b1 = new JButton("1");
    protected JButton b2 = new JButton("2");
    protected JButton b3 = new JButton("3");
    protected JButton b4 = new JButton("4");
    protected JButton b5 = new JButton("5");
    protected JButton b6 = new JButton("6");
    protected JButton b7 = new JButton("7");
    protected JButton b8 = new JButton("8");
    protected JButton b9 = new JButton("9");
    protected JButton b0 = new JButton("0");

    protected JButton addition = new JButton("+");
    protected JButton subtraction = new JButton("-");
    protected JButton multiplication = new JButton("*");
    protected JButton division = new JButton("/");
    protected JButton result = new JButton("=");
    protected JButton allClear = new JButton("C");
    protected JButton decimalPoint = new JButton(".");

    public Calculator()
    {
        super("Calculator");
        Handler handler = new Handler();

        allClear.addActionListener(handler);
        addition.addActionListener(handler);
        subtraction.addActionListener(handler);
        multiplication.addActionListener(handler);
        division.addActionListener(handler);
        result.addActionListener(handler);
        decimalPoint.addActionListener(handler);

        b0.addActionListener(handler);
        b1.addActionListener(handler);
        b2.addActionListener(handler);
        b3.addActionListener(handler);
        b4.addActionListener(handler);
        b5.addActionListener(handler);
        b6.addActionListener(handler);
        b7.addActionListener(handler);
        b8.addActionListener(handler);
        b9.addActionListener(handler);

        addition.setToolTipText("Addition");
        subtraction.setToolTipText("Subtraction");
        multiplication.setToolTipText("Multiplication");
        division.setToolTipText("Division");
        result.setToolTipText("Result");
        allClear.setToolTipText("All Clear");
        decimalPoint.setToolTipText("Decimal point");

        display = new JTextField(10);
        display.setBorder(BorderFactory.createLineBorder(Color.CYAN));

        // Set a panel's layout manager using the JPanel constructor

        JPanel mainPanel = new JPanel(new GridBagLayout());

        GridBagConstraints c = new GridBagConstraints();
        c.gridy = 0;
        c.gridwidth = 3;
        c.fill = GridBagConstraints.HORIZONTAL;
        c.insets = new Insets(5, 5, 5, 5);
        mainPanel.add(display, c);

        c = new GridBagConstraints();
        c.gridy = 0;
        c.gridwidth = 1;
        c.insets = new Insets(5, 5, 5, 5);
        mainPanel.add(allClear, c);

        c = new GridBagConstraints();
        c.gridy = 1;
        c.gridwidth = 1;
        c.insets = new Insets(5, 5, 5, 5);
        mainPanel.add(b1, c);

        c = new GridBagConstraints();
        c.gridy = 1;
        c.gridwidth = 1;
        c.insets = new Insets(5, 5, 5, 5);
        mainPanel.add(b2, c);

        c = new GridBagConstraints();
        c.gridy = 1;
        c.gridwidth = 1;
        c.insets = new Insets(5, 5, 5, 5);
        mainPanel.add(b3, c);

        c = new GridBagConstraints();
        c.gridy = 1;
        c.gridwidth = 1;
        c.insets = new Insets(5, 5, 5, 5);
        mainPanel.add(division, c);

        c = new GridBagConstraints();
        c.gridy = 2;
        c.insets = new Insets(5, 5, 5, 5);
        mainPanel.add(b4, c);

        c = new GridBagConstraints();
        c.gridy = 2;
        c.insets = new Insets(5, 5, 5, 5);
        mainPanel.add(b5, c);

        c = new GridBagConstraints();
        c.gridy = 2;
        c.insets = new Insets(5, 5, 5, 5);
        mainPanel.add(b6, c);

        c = new GridBagConstraints();
        c.gridy = 2;
        c.insets = new Insets(5, 5, 5, 5);
        mainPanel.add(multiplication, c);

        c = new GridBagConstraints();
        c.gridy = 3;
        c.insets = new Insets(5, 5, 5, 5);
        mainPanel.add(b7, c);

        c = new GridBagConstraints();
        c.gridy = 3;
        c.insets = new Insets(5, 5, 5, 5);
        mainPanel.add(b8, c);

        c = new GridBagConstraints();
        c.gridy = 3;
        c.insets = new Insets(5, 5, 5, 5);
        mainPanel.add(b9, c);

        c = new GridBagConstraints();
        c.gridy = 3;
        c.insets = new Insets(5, 5, 5, 5);
        mainPanel.add(subtraction, c);

        c = new GridBagConstraints();
        c.gridy = 4;
        c.insets = new Insets(5, 5, 5, 5);
        mainPanel.add(b0, c);

        c = new GridBagConstraints();
        c.gridy = 4;
        c.insets = new Insets(5, 5, 5, 5);
        mainPanel.add(decimalPoint, c);

        c = new GridBagConstraints();
        c.gridy = 4;
        c.insets = new Insets(5, 5, 5, 5);
        mainPanel.add(result, c);

        c = new GridBagConstraints();
        c.gridy = 4;
        c.insets = new Insets(5, 5, 5, 5);
        mainPanel.add(addition, c);

        add(mainPanel);
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        pack();
    }

Answer 1

您需要设置约束的weightx和weighty。这些值之间的关系控制“未使用”空间沿单元的分布方式。请参阅GridBagConstraints documentation 。

您可以将 weightx 和 weighty 约束设置为 1.0 或任何其他严格的正值。

fill 字段必须设置为 BOTH，以便每个按钮占据其整个单元格。

迷你示例，为了可读性而缩小:

public class MiniCalculator extends JFrame {

    public static void main(String[] args) {
        new MiniCalculator().setVisible(true);
    }

    private JTextField display = new JTextField(10);

    private JButton clear = new JButton("C");
    private JButton b1 = new JButton("1");
    private JButton b2 = new JButton("2");
    private JButton b3 = new JButton("3");

    public MiniCalculator() {
        setDefaultCloseOperation(DISPOSE_ON_CLOSE);
        setLayout(new GridBagLayout());

        GridBagConstraints constraint = new GridBagConstraints();
        constraint.insets = new Insets(5, 5, 5, 5);
        constraint.weighty = 1.0;
        constraint.weightx = 1.0;

        constraint.gridy = 0;
        constraint.gridwidth = 2;
        constraint.fill = GridBagConstraints.HORIZONTAL;
        add(display, constraint);

        constraint.gridwidth = 1;
        constraint.fill = GridBagConstraints.BOTH;
        add(clear, constraint);

        constraint.gridy = 1;
        add(b1, constraint);
        add(b2, constraint);
        add(b3, constraint);

        pack();
        setLocationRelativeTo(null);
    }
}

注意:无需创建所有约束，只需创建一个并在添加组件之间更改它即可。添加组件时会克隆约束。