Swing全尺寸JPanel

Question

如何達到outerPanel的全寬度？

private JPanel createLabelPanel() { 

     final JToolTip tt = new JToolTip(); 
     //tt.setSize(new Dimension(100,200)); 
     final CompoundBorder cb = new CompoundBorder(tt.getBorder(), BorderFactory.createEmptyBorder(2, 2, 2, 2)); 
     final JPanel innerPanel = new JPanel(); 
     innerPanel.setBorder(BorderFactory.createLineBorder(Color.BLACK)); 

     innerPanel.setBorder(cb); 
     innerPanel.setBackground(tt.getBackground()); 
     innerPanel.add(displayLabel); 
     innerPanel.setBorder(BorderFactory.createLineBorder(Color.GREEN)); 

     final JScrollPane tooltipscrool = new JScrollPane(innerPanel); 
     //tooltipscrool.setMinimumSize(new Dimension(200,100)); 
     tooltipscrool.setPreferredSize(new Dimension(100,120)); 
     tooltipscrool.setBorder(BorderFactory.createLineBorder(Color.BLACK)); 

     final JPanel outerPanel = new JPanel(); 
     outerPanel.add(tooltipscrool); 
     outerPanel.setBorder(BorderFactory.createLineBorder(Color.GREEN)); 
     //outerPanel.set 
     return outerPanel; 
    } 

讓我：

，我的目標是擁有innerPanel的全寬（綠色的）。

Answer 1

JPanel默認使用FlowLayout，這傾向於使用每個組件的首選大小來定義它們的大小。

改用BorderLayout，例如...

final JPanel outerPanel = new JPanel(new BorderLayout()); 

看看How to layout components within a container更多細節

你也應該避免使用setPreferredSize如果可能的話，請Should I avoid the use of set(Preferred|Maximum|Minimum)Size methods in Java Swing?更多細節