如何覆盖JPanel的默认布局管理器？

Question

如何覆盖JPanel后代的默认布局管理器？我有自己的课程，希望null成为默认课程。

Answer 1

使用JPanel构造函数，它们接受LayoutManager：

import java.awt.LayoutManager;

import javax.swing.JPanel;

public class MyPanel extends JPanel {
    public MyPanel() {
        this(true);
    }

    public MyPanel(boolean isDoubleBuffered) {
        super(null, isDoubleBuffered);
    }

    public MyPanel(LayoutManager layout, boolean isDoubleBuffered) {
        super(layout, isDoubleBuffered);
    }

    public MyPanel(LayoutManager layout) {
        this(layout, true);
    }
}

Answer 2

您可以在子类中添加初始化程序块：

public class MyPanel extends JPanel {

    {
         setLayout(null);
    }

    // ... class implementation
}

Answer 3

JPanel panel = new JPanel();
panel.setLayout(new MyLayout());

或

contentPane.setLayout(null);