GridLayout 抛出非法组件位置

Question

默认情况下，GridLayout(5,3) 将以这种方式添加组件：

A B C
D E F
G H I
J K L
M N O

将组件布置在以下位置：

A F K
B G L
C H M
D I N
E J O

我有这个代码：

//imports...

public class GridLayoutProblem {

    private static final int NUM_ROWS = 5, NUM_COLMS=3;
    private JPanel mainPanel = new JPanel();
    private JPanel buttonPannel = new JPanel(new GridLayout(NUM_ROWS, NUM_COLMS));

    private JButton btnA = new JButton("A");
    private JButton btnB = new JButton("B");
    //same with C, D...
    private JButton btnO = new JButton("O");

    private JComponent[] buttons = {
            btnA, btnB, btnC, btnD, btnE,
            btnF, btnG, btnH, btnI, btnJ,
            btnK, btnL, btnM, btnN, btnO
    };

    public GridLayoutProblem(){
        int i=0;
        for (JComponent button : buttons){
            int index = i%NUM_ROWS*NUM_COLMS+i/NUM_ROWS;
            buttonPannel.add(button,index);
            i++;
        }
        mainPanel.add(buttonPannel);
    }
    //...

但结果是：线程异常 "AWT-EventQueue-0" java.lang.IllegalArgumentException: 非法组件位置。

Answer 1

将 buttonPannel.add(button,index); 更改为 buttonPannel.add(buttons[index]);。（你不需要 foreach 循环）GridLayout 总是像你在第一个例子中展示的那样添加组件，但是如果你可以对 index 进行正确的计算（参见其他答案），那么它会像 "A,F,K,B...",你可以达到你想要的。

运行下面的代码可以查看如何添加按钮：

import java.awt.BorderLayout;
import java.awt.GridLayout;

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

//imports...

public class GridLayoutProblem {

    private static final int NUM_ROWS = 5, NUM_COLMS=3;
    private static JPanel mainPanel = new JPanel();
    private JPanel buttonPannel = new JPanel(new GridLayout(NUM_ROWS, NUM_COLMS));

    private JButton btnA = new JButton("A");
    private JButton btnB = new JButton("B");
    private JButton btnC = new JButton("C");
    private JButton btnD = new JButton("D");
    private JButton btnE = new JButton("E");
    private JButton btnF = new JButton("F");
    private JButton btnG = new JButton("G");
    private JButton btnH = new JButton("H");
    private JButton btnI = new JButton("I");
    private JButton btnJ = new JButton("J");
    private JButton btnK = new JButton("K");
    private JButton btnL = new JButton("L");
    private JButton btnM = new JButton("M");
    private JButton btnN = new JButton("N");
    private JButton btnO = new JButton("O");

    private JComponent[] buttons = {
            btnA, btnB, btnC, btnD, btnE,
            btnF, btnG, btnH, btnI, btnJ,
            btnK, btnL, btnM, btnN, btnO
    };

    public static void main(String[] args) {
        new GridLayoutProblem();
    }

    public GridLayoutProblem(){
        JFrame frame = new JFrame();
        new Thread(new Runnable() {
            public void run() {
                for (int i = 0; i < NUM_ROWS * NUM_COLMS; i++) {
                    int index = i%NUM_COLMS*NUM_ROWS+i/NUM_COLMS;
                    buttonPannel.add(buttons[index]);
                    frame.revalidate();
                    frame.repaint();
                    try {
                        Thread.sleep(1000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        }).start();
        mainPanel.add(buttonPannel);
        frame.getContentPane().add(mainPanel);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(500,500);
        frame.setVisible(true);
    }
}

Answer 2

我做了一个快速测试，似乎你不能跳过索引并将元素添加到更高的索引。

所以你的选择是做这样的事情，

    for (int i = 0; i < NUM_ROWS*NUM_COLMS; i++){
        int index = i%NUM_COLMS*NUM_ROWS+i/NUM_COLMS; // Note the change in calculation. Just interchange rows and colms from your algo.
        buttonPannel.add(button[index],i);
    }

GridLayout 抛出非法组件位置

GridLayout throws illegal component position

java

swing

layout-manager

grid-layout