隱藏在JPanel中的Java組件

Question

我有兩個JPanels，每個都有一堆JButtons。包含另外兩個的JPanel具有BoxLayout，另外兩個JPanels是FlowLayout。問題在於窗口大小調整以使按鈕環繞時，第一個和第二個面板中的按鈕（p0，p2）被其相應面板的邊緣覆蓋。有任何想法嗎？

import java.awt.Dimension; 
import java.awt.FlowLayout; 
import java.awt.Rectangle; 

import javax.swing.BoxLayout; 
import javax.swing.JButton; 
import javax.swing.JFrame; 
import javax.swing.JPanel; 
import javax.swing.JScrollPane; 
import javax.swing.Scrollable; 
import javax.swing.border.TitledBorder; 

public class Test { 
    public static void main(String[] args) { 
     JFrame frame = new JFrame(); 
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     JPanel p0 = new JPanel(); 
     p0.setLayout(new FlowLayout()); 
     p0.setBorder(new TitledBorder("p0")); 
     JPanel p1 = new JPanel(); 
     p1.setLayout(new FlowLayout()); 
     p1.setBorder(new TitledBorder("p1")); 
     CustomPanel panel = new CustomPanel(); 
     JScrollPane sp = new JScrollPane(panel); 
     panel.add(p0); 
     panel.add(p1); 
     frame.add(sp); 
     panel.setLayout(new BoxLayout(panel, BoxLayout.PAGE_AXIS)); 
     p0.add(new JButton("Hello World!")); 
     p0.add(new JButton("Hello World!")); 
     p0.add(new JButton("Hello World!")); 
     p0.add(new JButton("Hello World!")); 
     p0.add(new JButton("Hello World!")); 
     p0.add(new JButton("Hello World!")); 
     p0.add(new JButton("Hello World!")); 
     p0.add(new JButton("Hello World!")); 
     p1.add(new JButton("Hello World!")); 
     p1.add(new JButton("Hello World!")); 
     p1.add(new JButton("Hello World!")); 
     p1.add(new JButton("Hello World!")); 
     p1.add(new JButton("Hello World!")); 
     p1.add(new JButton("Hello World!")); 
     p1.add(new JButton("Hello World!")); 
     p1.add(new JButton("Hello World!")); 
     frame.setVisible(true); 
    } 

} 

class CustomPanel extends JPanel implements Scrollable { 

    @Override 
    public Dimension getPreferredScrollableViewportSize() { 
     return null; 
    } 

    @Override 
    public int getScrollableBlockIncrement(Rectangle visibleRect, int orientation, int direction) { 
     return 0; 
    } 

    @Override 
    public boolean getScrollableTracksViewportHeight() { 
     return false; 
    } 

    @Override 
    public boolean getScrollableTracksViewportWidth() { 
     return true; 
    } 

    @Override 
    public int getScrollableUnitIncrement(Rectangle visibleRect, int orientation, int direction) { 
     return 0; 
    } 

} 

Answer 1

的的FlowLayout不重新計算最佳尺寸時部件包裹。

相反，您可以使用Wrap Layout。

所有你需要改變的是：

//p0.setLayout(new FlowLayout()); 
p0.setLayout(new WrapLayout());