java JButton 数组的动作侦听器
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Action listener for JButton array
提问by user530809
Let's say I have a program with 2D array of buttons, and when you click one of them it turns red. I didn't want to declare every single button seperately so I just created JButton[][] array for them. The problem is that I don't know how to use action listener on any of the buttons in the array so it would change the color of this particular button, and none of related questions is relevant to this. I tried to use "for" but it doesn't help:
假设我有一个带有二维按钮阵列的程序，当您单击其中一个按钮时，它会变成红色。我不想单独声明每个按钮，所以我只是为它们创建了 JButton[][] 数组。问题是我不知道如何在数组中的任何按钮上使用动作侦听器，因此它会更改此特定按钮的颜色，并且没有任何相关问题与此相关。我尝试使用“for”，但没有帮助：
package appli;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class MainW extends JFrame implements ActionListener {
public MainW(){
setSize(640,480);
setTitle("title");
setLayout(null);
JButton[][] btnz = new JButton[5][5];
for(Integer i=0;i<5;i++)
{
for(Integer j=0;j<5;j++)
{
btnz[i][j]= new JButton("");
btnz[i][j].setBackground(Color.WHITE);
btnz[i][j].setBounds(10+20*i,10+20*j,20,20);
add(btnz[i][j]);
btnz[i][j].addActionListener(this);
}
}
setDefaultCloseOperation(EXIT_ON_CLOSE);
setVisible(true);
}
public void actionPerformed(ActionEvent e){
for(Integer i=0;i<5;i++)
{
for(Integer j=0;j<5;j++)
{
if (e.getSource()==btnz[i][j]);
{
btnz[i][j].setBackground(Color.RED);
}
}
}
}
}
回答by akf
have you tried:
你有没有尝试过：
public void actionPerformed(ActionEvent e){
if( e.getSource() instanceof JButton) {
((JButton)e.getSource()).setBackground(Color.red);
}
}
One reason why your code might not work is that the JButton[][]you use to create your buttons is local to your MainWconstructor. The approach I have provided will allow you to disregard this scoping issue. It will also remove your iterative approach, and replace it with a more efficient solution. In your code, even if the event is triggered by the first item in your list, or even not triggered by one of your buttons, you will always iterate over the entire 2D array and test each.
您的代码可能无法工作的原因之一是JButton[][]您用来创建按钮的对于您的MainW构造函数来说是本地的。我提供的方法将允许您忽略此范围界定问题。它还将删除您的迭代方法，并用更有效的解决方案取而代之。在您的代码中，即使事件是由列表中的第一项触发，或者甚至不是由您的一个按钮触发，您也将始终遍历整个 2D 数组并测试每个。
