覆蓋選擇顏色 - JTree的

Question

有在DefaultTreeCellRenderer一種稱爲setBackgroundSelectionColor()，讓你當你選擇一個JTree一個項目更改選擇的顏色。當我進入DefaultTreeCellRenderer的源代碼時，選擇顏色在paint()之前設置爲getBackgroundSelectionColor()。

下面的代碼中，我試圖通過簡單覆蓋paint方法來更改選擇顏色。問題是，即使在paint方法中手動設置，顏色保持不變。即使在paint中不再使用getBackgroundSelectionColor()，方法setBackgroundSelectionColor()仍然有效。

這是爲什麼，以及如何正確覆蓋顏色？
不使用setBackgroundSelectionColor()

import java.awt.*; 

import javax.swing.*; 
import javax.swing.tree.*; 

@SuppressWarnings("serial") 
public class DirectoryExplorer extends JFrame { 
    private DirectoryExplorer() { 
     super("Directory Explorer"); 
     setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     setLayout(new GridLayout(1, 1)); 
     createPanel(); 
     setSize(800,600); 
     setVisible(true); 
    } 

    private void createPanel() { 
     JPanel panel = new JPanel(new GridLayout(1, 1)); 
     JTree tree = new JTree(); 

     paintRenderer pR = new paintRenderer(); 
     tree.setCellRenderer(pR); 

     //pR.setBackgroundSelectionColor(Color.RED); //Why does this work when changing value in paint doesn't 

     panel.add(new JScrollPane(tree)); 
     getContentPane().add(panel); 
    } 

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

    private class paintRenderer extends DefaultTreeCellRenderer { 
     @Override 
     public void paint(Graphics g) { 
      Color bColor; 

      if (selected) { 
       bColor = Color.RED;//= getBackgroundSelectionColor(); 
      } else { 
       bColor = getBackgroundNonSelectionColor(); 
       if (bColor == null) { 
        bColor = getBackground(); 
       } 
      } 

      //super.paint(g); //Paints the correct colors but no text 

      int imageOffset = -1; 
      if (bColor != null) { 
       imageOffset = getLabelStart(); 
       g.setColor(bColor); 
       if(getComponentOrientation().isLeftToRight()) { 
        g.fillRect(imageOffset, 0, getWidth() - imageOffset, getHeight()); 
       } else { 
        g.fillRect(0, 0, getWidth() - imageOffset, getHeight()); 
       } 
      } 

      if (hasFocus) { 
       if (imageOffset == -1) { 
        imageOffset = getLabelStart(); 
       } 

       if(getComponentOrientation().isLeftToRight()) { 
        paintFocus(g, imageOffset, 0, getWidth() - imageOffset, getHeight(), bColor); 
       } else { 
        paintFocus(g, 0, 0, getWidth() - imageOffset, getHeight(), bColor); 
       } 
      } 
      super.paint(g); //Paints text but wrong colors 
     } 

     private void paintFocus(Graphics g, int x, int y, int w, int h, Color notColor) { 
      Color bsColor = Color.RED;//= getBorderSelectionColor(); 

      if (bsColor != null && selected) { 
       g.setColor(bsColor); 
       g.drawRect(x, y, w - 1, h - 1); 
      } 
     } 

     private int getLabelStart() { 
      Icon currentI = getIcon(); 
      if(currentI != null && getText() != null) { 
       return currentI.getIconWidth() + Math.max(0, getIconTextGap() - 1); 
      } 
      return 0; 
     } 
    } 
} 

編輯
什麼它目前看起來像

Answer 1

的問題是，你要重寫的paint(...)代替paintComponent(...)

如在此answer中所述，您不應將paint替換爲不是頂層容器的東西，而應該覆蓋paintComponent。

更改代碼看起來像這樣。

@Override 
public void paintComponent(Graphics g) { 
... 
super.paintComponent(g); 
} 

例如

import java.awt.*; 

import javax.swing.*; 
import javax.swing.tree.*; 

@SuppressWarnings("serial") 
public class DirectoryExplorer extends JFrame { 
    private DirectoryExplorer() { 
     super("Directory Explorer"); 
     setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     setLayout(new GridLayout(1, 1)); 
     createPanel(); 
     setSize(800,600); 
     setVisible(true); 
    } 

    private void createPanel() { 
     JPanel panel = new JPanel(new GridLayout(1, 1)); 
     JTree tree = new JTree(); 

     paintRenderer pR = new paintRenderer(); 
     tree.setCellRenderer(pR); 

     panel.add(new JScrollPane(tree)); 
     getContentPane().add(panel); 
    } 

    public static void main(String[] args) { 
     EventQueue.invokeLater(() -> new DirectoryExplorer()); 
    } 

    private class paintRenderer extends DefaultTreeCellRenderer { 
     @Override 
     public void paintComponent(Graphics g) { 
      Color bColor; 

      if (selected) { 
       bColor = Color.RED; 
      } else { 
       bColor = getBackgroundNonSelectionColor(); 
       if (bColor == null) { 
        bColor = getBackground(); 
       } 
      } 

      int imageOffset = -1; 
      if (bColor != null) { 
       imageOffset = getLabelStart(); 
       g.setColor(bColor); 
       if(getComponentOrientation().isLeftToRight()) { 
        g.fillRect(imageOffset, 0, getWidth() - imageOffset, getHeight()); 
       } else { 
        g.fillRect(0, 0, getWidth() - imageOffset, getHeight()); 
       } 
      } 

      if (hasFocus) { 
       if (imageOffset == -1) { 
        imageOffset = getLabelStart(); 
       } 

       if(getComponentOrientation().isLeftToRight()) { 
        paintFocus(g, imageOffset, 0, getWidth() - imageOffset, getHeight()); 
       } else { 
        paintFocus(g, 0, 0, getWidth() - imageOffset, getHeight()); 
       } 
      } 
      super.paintComponent(g); 
     } 

     private void paintFocus(Graphics g, int x, int y, int w, int h) { 
      Color bsColor = Color.RED; 

      if (bsColor != null && selected) { 
       g.setColor(bsColor); 
       g.drawRect(x, y, w - 1, h - 1); 
      } 
     } 

     private int getLabelStart() { 
      Icon currentI = getIcon(); 
      if(currentI != null && getText() != null) { 
       return currentI.getIconWidth() + Math.max(0, getIconTextGap() - 1); 
      } 
      return 0; 
     } 
    } 
}