爲什麼JScrollPane中的這個列表不能對齊？

Question

我似乎無法得到此工作。我試圖從右到左對齊列表，但它不工作，我似乎無法找到修復。

這裏是我的代碼表明：

下面的代碼：

import java.awt.BorderLayout; 
import java.awt.Color; 
import java.awt.GridBagConstraints; 
import java.awt.GridBagLayout; 
import java.awt.GridLayout; 

import javax.swing.JFrame; 
import javax.swing.JLabel; 
import javax.swing.JPanel; 
import javax.swing.JScrollPane; 

public class Example { 

    public static void main(String[] args) { 
     JFrame jFrame = new JFrame(); 
     jFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     jFrame.setSize(400, 200); 
     // main panel 
     JPanel pan = new JPanel(); 
     pan.setLayout(new GridLayout(1, 2)); 
     pan.setBackground(Color.BLUE); 
     jFrame.getContentPane().add(pan, BorderLayout.CENTER); 
     jFrame.show(); 
     // left panel 
     JPanel left = getContentPanel(); 
     left.setBackground(Color.ORANGE); 
     pan.add(left); 
     // right panel (with scroll pane) 
     JPanel right = getContentPanel(); 
     right.setBackground(Color.YELLOW); 
     JScrollPane scr = new JScrollPane(right); 
     scr.setBackground(Color.CYAN); 
     scr.setAlignmentX(JScrollPane.LEFT_ALIGNMENT); 
     pan.add(scr); 
    } 

    private static JPanel getContentPanel() { 
     JPanel rtn = new JPanel(); 
     rtn.setLayout(new GridBagLayout()); 
     GridBagConstraints cs = new GridBagConstraints(); 
     cs.gridx = 0; 
     for (int i = 0; i < 100; i++) { 
      JLabel label = new JLabel("Item " + (i + 1)); 
      label.setBackground(Color.DARK_GRAY); 
      cs.gridy = i; 
      rtn.add(label, cs); 
     } 
     rtn.setBackground(Color.GREEN); 
     return rtn; 
    } 

} 

Answer 1

最基本的答案是，setAlignmentX不會做你認爲它

相反，您應該使用GridBagConstraints#anchor（和GridBagConstraints#weightx約束來更改對齊方式，對於e xample ...

import java.awt.BorderLayout; 
import java.awt.Color; 
import java.awt.EventQueue; 
import java.awt.GridBagConstraints; 
import java.awt.GridBagLayout; 
import java.awt.GridLayout; 
import javax.swing.JFrame; 
import javax.swing.JLabel; 
import javax.swing.JPanel; 
import javax.swing.JScrollPane; 
import javax.swing.UIManager; 
import javax.swing.UnsupportedLookAndFeelException; 

public class Example { 

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

    public Example() { 
     EventQueue.invokeLater(new Runnable() { 
      @Override 
      public void run() { 
       try { 
        UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName()); 
       } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) { 
        ex.printStackTrace(); 
       } 

       JFrame jFrame = new JFrame(); 
       jFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
       // main panel 
       JPanel pan = new JPanel(); 
       pan.setLayout(new GridLayout(1, 2)); 
       pan.setBackground(Color.BLUE); 
       jFrame.getContentPane().add(pan, BorderLayout.CENTER); 
       // left panel 
       JPanel left = getContentPanel(GridBagConstraints.CENTER); 
       left.setBackground(Color.ORANGE); 
       pan.add(new JScrollPane(left)); 
       // right panel (with scroll pane) 
       JPanel right = getContentPanel(GridBagConstraints.WEST); 
       right.setBackground(Color.YELLOW); 
       JScrollPane scr = new JScrollPane(right); 
       scr.setBackground(Color.CYAN); 
       scr.setAlignmentX(JScrollPane.LEFT_ALIGNMENT); 
       pan.add(scr); 

       jFrame.setSize(400, 400); 
       jFrame.setVisible(true); 
      } 
     }); 
    } 

    private static JPanel getContentPanel(int anchor) { 
     JPanel rtn = new JPanel(); 
     rtn.setLayout(new GridBagLayout()); 
     GridBagConstraints cs = new GridBagConstraints(); 
     cs.gridx = 0; 
     cs.anchor = anchor; 
     cs.weightx = 1; 
     for (int i = 0; i < 100; i++) { 
      JLabel label = new JLabel("Item " + (i + 1)); 
      label.setBackground(Color.DARK_GRAY); 
      cs.gridy = i; 
      rtn.add(label, cs); 
     } 
     rtn.setBackground(Color.GREEN); 
     return rtn; 
    } 

}