カスタムJtextField

Question

私は、イメージとヒントを使ってより美しいJTextFieldを作成しようとしています。私はこのチュートリアルhttps://gmigdos.wordpress.com/2010/03/30/java-a-custom-jtextfield-for-searching/に従った。

私は取得していますエラーは、このです：

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException 
at com.jd.swing.custom.component.jtextfield.JIconTextField.paintComponent(JIconTextField.java:53) 
at com.jd.swing.custom.component.jtextfield.JSearchTextField.paintComponent(JSearchTextField.java:49) 
at javax.swing.JComponent.paint(JComponent.java:1054) 
at javax.swing.JComponent.paintChildren(JComponent.java:887) 
at javax.swing.JComponent.paint(JComponent.java:1063) 
at javax.swing.JComponent.paintChildren(JComponent.java:887) 
at javax.swing.JComponent.paint(JComponent.java:1063) 
at javax.swing.JComponent.paintChildren(JComponent.java:887) 
at javax.swing.JComponent.paint(JComponent.java:1063) 
at javax.swing.JComponent.paintChildren(JComponent.java:887) 
at javax.swing.JComponent.paint(JComponent.java:1063) 
at javax.swing.JLayeredPane.paint(JLayeredPane.java:585) 
at javax.swing.JComponent.paintChildren(JComponent.java:887) 
at javax.swing.JComponent.paintToOffscreen(JComponent.java:5228) 
at javax.swing.RepaintManager.paint(RepaintManager.java:1209) 
at javax.swing.JComponent.paint(JComponent.java:1040) 
at java.awt.GraphicsCallback$PaintCallback.run(GraphicsCallback.java:39) 
at sun.awt.SunGraphicsCallback.runOneComponent(SunGraphicsCallback.java:78) 
at sun.awt.SunGraphicsCallback.runComponents(SunGraphicsCallback.java:115) 
at java.awt.Container.paint(Container.java:1967) 
at java.awt.Window.paint(Window.java:3877) 
at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:781) 
at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:728) 
at javax.swing.RepaintManager.prePaintDirtyRegions(RepaintManager.java:677) 
at javax.swing.RepaintManager.access$700(RepaintManager.java:59) 
at javax.swing.RepaintManager$ProcessingRunnable.run(RepaintManager.java:1621) 
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:251) 
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:701) 
at java.awt.EventQueue.access$000(EventQueue.java:102) 
at java.awt.EventQueue$3.run(EventQueue.java:662) 
at java.awt.EventQueue$3.run(EventQueue.java:660) 
at java.security.AccessController.doPrivileged(Native Method) 
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76) 
at java.awt.EventQueue.dispatchEvent(EventQueue.java:671) 
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:244) 
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:163) 
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:151) 
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:147) 
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:139) 
at java.awt.EventDispatchThread.run(EventDispatchThread.java:97) 

JIconTextField.java

public class JIconTextField extends JTextField{ 

    /** 
    * 
    */ 
    private static final long serialVersionUID = -8242515712056236296L; 
    private Icon icon; 
    private Insets dummyInsets; 

    public JIconTextField(){ 
     super(); 
     this.icon = null; 

     Border border = UIManager.getBorder("TextField.border"); 
     JTextField dummy = new JTextField(); 
     if(border!=null){ 
      this.dummyInsets = border.getBorderInsets(dummy); 
     }else{ 
      this.dummyInsets = null; 
     } 
    } 

    public void setIcon(Icon icon){ 
     this.icon = icon; 
    } 

    public Icon getIcon(){ 
     return this.icon; 
    } 

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

     int textX = 2; 

     if(this.icon!=null){ 
      int iconWidth = icon.getIconWidth(); 
      int iconHeight = icon.getIconHeight(); 
      int x = dummyInsets.left -5;//this is our icon's x 
      textX = x+iconWidth+2; //this is the x where text should start 
      int y = (this.getHeight() - iconHeight)/2; 
      icon.paintIcon(this, g, x, y); 
     } 
     setMargin(new Insets(2, textX, 2, 2)); 
    } 
} 

Answer 1

私はこの

if(this.icon!=null){ 
     int iconWidth = icon.getIconWidth(); 
     int iconHeight = icon.getIconHeight(); 
     int x = (dummyInsets==null) ? 0 : dummyInsets.left - 5; 
     textX = x+iconWidth+2; 
     int y = (this.getHeight() - iconHeight)/2; 
     icon.paintIcon(this, g, x, y); 
    } 

しようと、それはトレースバックがあなたを語っている