关于使用 awt 和 swing 的布局答案

【问题标题】：About layouts using awt and swing关于使用 awt 和 swing 的布局
【发布时间】：2019-04-26 07:34:09
【问题描述】：

所以我尝试使用GridBagLayout 制作基本的计算器布局，在浏览了一些文档后，我想出了这个：

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

public class Test {
    public static void main(String args[]) {
        JFrame f = new JFrame("Calculator");
        f.setSize(1000, 550);
        f.setResizable(false);

        JPanel p1 = new JPanel();
        p1.setLayout(new GridBagLayout());
        GridBagConstraints c = new GridBagConstraints();

        JTextField out = new JTextField();
        out.setColumns(15);
        c.gridx = 0;
        c.gridy = 0;
        //c.gridwidth=4;
        p1.add(out, c);

        JButton b1 = new JButton("CLEAR");
        c.gridx = 0;
        c.gridy = 1;
        c.fill = GridBagConstraints.HORIZONTAL;
        p1.add(b1, c);

        JButton b2 = new JButton("ERASE");
        c.gridx = 1;
        c.gridy = 1;
        c.fill = GridBagConstraints.HORIZONTAL;
        p1.add(b2, c);

        JButton b3 = new JButton("ROOT");
        c.gridx = 2;
        c.gridy = 1;
        c.fill = GridBagConstraints.HORIZONTAL;
        p1.add(b3, c);

        JButton b4 = new JButton("÷");
        c.gridx = 3;
        c.gridy = 1;
        c.fill = GridBagConstraints.HORIZONTAL;
        p1.add(b4, c);

        JButton b5 = new JButton("7");
        c.gridx = 0;
        c.gridy = 2;
        c.fill = GridBagConstraints.HORIZONTAL;
        p1.add(b5, c);

        JButton b6 = new JButton("8");
        c.gridx = 1;
        c.gridy = 2;
        c.fill = GridBagConstraints.HORIZONTAL;
        p1.add(b6, c);

        JButton b7 = new JButton("9");
        c.gridx = 2;
        c.gridy = 2;
        c.fill = GridBagConstraints.HORIZONTAL;
        p1.add(b7, c);

        JButton b8 = new JButton("X");
        c.gridx = 3;
        c.gridy = 2;
        c.fill = GridBagConstraints.HORIZONTAL;
        p1.add(b8, c);

        JButton b9 = new JButton("4");
        c.gridx = 0;
        c.gridy = 3;
        c.fill = GridBagConstraints.HORIZONTAL;
        p1.add(b9, c);

        JButton b10 = new JButton("5");
        c.gridx = 1;
        c.gridy = 3;
        c.fill = GridBagConstraints.HORIZONTAL;
        p1.add(b10, c);

        JButton b11 = new JButton("6");
        c.gridx = 2;
        c.gridy = 3;
        c.fill = GridBagConstraints.HORIZONTAL;
        p1.add(b11, c);

        JButton b12 = new JButton("+");
        c.gridx = 3;
        c.gridy = 3;
        c.fill = GridBagConstraints.HORIZONTAL;
        p1.add(b12, c);

        JButton b13 = new JButton("1");
        c.gridx = 0;
        c.gridy = 4;
        c.fill = GridBagConstraints.HORIZONTAL;
        p1.add(b13, c);

        JButton b14 = new JButton("2");
        c.gridx = 1;
        c.gridy = 4;
        c.fill = GridBagConstraints.HORIZONTAL;
        p1.add(b14, c);

        JButton b15 = new JButton("3");
        c.gridx = 2;
        c.gridy = 4;
        c.fill = GridBagConstraints.HORIZONTAL;
        p1.add(b15, c);

        JButton b16 = new JButton("-");
        c.gridx = 3;
        c.gridy = 4;
        c.fill = GridBagConstraints.HORIZONTAL;
        p1.add(b16, c);

        JButton b17 = new JButton();
        c.gridx = 0;
        c.gridy = 5;
        c.fill = GridBagConstraints.HORIZONTAL;
        //c.fill = GridBagConstraints.VERTICAL;
        p1.add(b17, c);

        JButton b18 = new JButton("0");
        c.gridx = 1;
        c.gridy = 5;
        c.fill = GridBagConstraints.HORIZONTAL;
        p1.add(b18, c);

        JButton b19 = new JButton();
        c.gridx = 2;
        c.gridy = 5;
        c.fill = GridBagConstraints.HORIZONTAL;
        p1.add(b19, c);

        JButton b20 = new JButton("=");
        c.gridx = 3;
        c.gridy = 5;
        c.fill = GridBagConstraints.HORIZONTAL;
        p1.add(b20, c);


        f.add(p1);
        f.setVisible(true);
    }

}

结果如下：

所以我取消了这一行的注释以将JTextField 延长到最后：

//c.gridwidth=4;

它做了这样奇怪的事情：

我不明白为什么只显示了网格的一列。这可能是什么原因造成的？我该怎么做才能解决这个问题？我希望 JTextField 扩展到所有列。

【问题讨论】：

标签： java swing layout awt gridbaglayout

【解决方案1】：

我会尝试为每个按钮添加权重。

【讨论】：

【解决方案2】：

您需要为下一个组件重置 gridwidth 值，因为您正在重用相同的约束对象：

c.gridwidth=4;
p1.add(out,c);

JButton b1= new JButton("CLEAR");
c.gridx=0;
c.gridy=1;
c.gridwidth=1; // added
c.fill = GridBagConstraints.HORIZONTAL;
p1.add(b1,c);

现在网格宽度为 1 将用于其余组件。

【讨论】：