java - 如何在要拉伸(stretch)的网格布局中创建 13 个中的最后一个按钮

Question

我在设计按钮时遇到问题，我创建了 13 并将其设为 5,3，但最后一个按钮没有拉伸(stretch)到 3 列的宽度。

它看起来像这样 example picture

这是我的代码，如果有人可以提供任何有用的建议，谢谢。

import javax.swing.*;
public class Frame extends JFrame
{
    public static void main(String[]args){

        JFrame myFrame = new JFrame("MyFrame");
        Panel myPanel = new Panel();
        myFrame.add(myPanel);
        myFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        myFrame.setSize(300,400);
        myFrame.setVisible(true);
    }
}

import javax.swing.*;
import java.awt.*;
public class Panel extends JPanel
{
    JButton zero,one,two,three,four,five,six,seven,eight,nine,clear, negative,convert;
    JRadioButton k2p,p2k;
    JTextArea area;
    ButtonGroup conversion;
    public Panel() {

        zero = new JButton("0");
        one = new JButton("1");
        two = new JButton("2");
        three = new JButton("3");
        four = new JButton("4");
        five = new JButton("5");
        six = new JButton("6");
        seven = new JButton("7");
        eight = new JButton("8");
        nine = new JButton("9");
        clear = new JButton("C");
        negative = new JButton("-");
        convert = new JButton("Convert");
        area = new JTextArea();

        conversion = new ButtonGroup();
        conversion.add(k2p= new JRadioButton("Kilograms to Pounds"));
        conversion.add(p2k= new JRadioButton("Pounds to Kilograms"));

        setLayout(new BorderLayout());

        JPanel westPanel = new JPanel();


        westPanel.setLayout(new GridLayout(5,3));

        westPanel.add(zero);
        westPanel.add(one);
        westPanel.add(two);
        westPanel.add(three);
        westPanel.add(four);
        westPanel.add(five);
        westPanel.add(six);
        westPanel.add(seven);
        westPanel.add(eight);
        westPanel.add(nine);
        westPanel.add(negative);
        westPanel.add(clear);
        westPanel.add(convert);



        add(westPanel,BorderLayout.CENTER);

    }

}

Answer 1

GridLayout将其空间平均分配给所有组件:

The GridLayout class is a layout manager that lays out a container's components in a rectangular grid. The container is divided into equal-sized rectangles, and one component is placed in each rectangle.

(强调我的)您的替代方案是其他布局管理器，如 GridBagLayout、GroupLayout 或使用复合布局，这意味着将布局管理器一个嵌套在另一个布局管理器中。

在这里，我将通过将 GridLayout 嵌套在 CENTER 位置的 BorderLayout 和 convert< 中来使用复合布局 按钮在 PAGE_END 位置:

class Panel extends JPanel {

    JButton[] numberButtons = new JButton[10];
    JButton nine, clear, negative, convert;

    public Panel() {

        for (int i = 0; i < numberButtons.length; i++)
            numberButtons[i] = new JButton(String.valueOf(i));
        clear = new JButton("C");
        negative = new JButton("-");
        convert = new JButton("Convert");

        setLayout(new BorderLayout());
        JPanel westPanel = new JPanel(new BorderLayout());

        JPanel buttonsPanel = new JPanel(new GridLayout(4, 3));
        for (int i = 0; i < numberButtons.length; i++)
            buttonsPanel.add(numberButtons[i]);
        buttonsPanel.add(negative);
        buttonsPanel.add(clear);

        westPanel.add(buttonsPanel);
        westPanel.add(convert, BorderLayout.PAGE_END);

        add(westPanel, BorderLayout.CENTER);
    }
}

我还为编号按钮创建了一个 JButton[]，这通常是更好的选择。您也可以在那里添加其他按钮，但我认为这只会产生不利影响。