java.lang.ArrayIndexOutOfBoundsExceptionハイライトを使用しています

Question

私はJTextFieldから選択されたテキストを取得しようとしています。 .getHighlighter（）関数が見つかりました。私は目的のテキストを取得しますが、例外をスローしてインデックスから外しています。誰も私になぜ教えてもらえますか？

PS：私もh！= nullとh [0]！= nullであるかどうかをチェックしました。同じ結果。

private void jTextField1MouseDragged(java.awt.event.MouseEvent evt) {           
    Highlight[] h = jTextField1.getHighlighter().getHighlights(); 
    jLabel2.setText("Selected text: " + jTextField1.getText().substring(h[0].getStartOffset(), h[0].getEndOffset())); 
} 

例外：

Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: 0 
at interfacesprueba1.Ej3b.jTextField1MouseDragged(Ej3b.java:110) 
at interfacesprueba1.Ej3b.access$000(Ej3b.java:14) 
at interfacesprueba1.Ej3b$1.mouseDragged(Ej3b.java:42) 
at java.awt.AWTEventMulticaster.mouseDragged(AWTEventMulticaster.java:320) 
at java.awt.Component.processMouseMotionEvent(Component.java:6583) 
at javax.swing.JComponent.processMouseMotionEvent(JComponent.java:3342) 
at java.awt.Component.processEvent(Component.java:6304) 
at java.awt.Container.processEvent(Container.java:2236) 
at java.awt.Component.dispatchEventImpl(Component.java:4891) 
at java.awt.Container.dispatchEventImpl(Container.java:2294) 
at java.awt.Component.dispatchEvent(Component.java:4713) 
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4888) 
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4542) 
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4466) 
at java.awt.Container.dispatchEventImpl(Container.java:2280) 
at java.awt.Window.dispatchEventImpl(Window.java:2750) 
at java.awt.Component.dispatchEvent(Component.java:4713) 
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758) 
at java.awt.EventQueue.access$500(EventQueue.java:97) 
at java.awt.EventQueue$3.run(EventQueue.java:709) 
at java.awt.EventQueue$3.run(EventQueue.java:703) 
at java.security.AccessController.doPrivileged(Native Method) 
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76) 
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86) 
at java.awt.EventQueue$4.run(EventQueue.java:731) 
at java.awt.EventQueue$4.run(EventQueue.java:729) 
at java.security.AccessController.doPrivileged(Native Method) 
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76) 
at java.awt.EventQueue.dispatchEvent(EventQueue.java:728) 
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201) 
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116) 
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105) 
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101) 
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93) 
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82) 

Answer 1

あなたはこの

private void jTextField1MouseDragged(java.awt.event.MouseEvent evt) { 
     Highlight[] h = jTextField1.getHighlighter().getHighlights(); 
     if (h != null && h.length > 0) { 
      jLabel2.setText(
        "Selected text: " + jTextField1.getText().substring(h[0].getStartOffset(), h[0].getEndOffset())); 
     } 
    }