Netbeans IDE中的Java Swing空指針異常

Question

我對Java還是很陌生，我已經開始使用netwings Java IDE 8.2使用swing創建一個簡單的GUI項目，並且遇到了空指針異常。

為了查看問題的根源，我將大部分代碼移到了底部，但仍然出現了僅運行這些代碼行的異常。

package finalmodel;
import javax.swing.*;


public class FinalModel extends JFrame {

    public static void main (String[] args) {

        new FinalModel();
    }

    public FinalModel () {

        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setVisible(true);

    }

}

該應用程序運行良好，據我所知，該異常不會影響功能（窗口會彈出，並且可以從上述代碼成功關閉），但是該異常會在關閉窗口時拋出。

IDE給我的堆棧跟蹤是

java.lang.NullPointerException: peer
    at sun.awt.windows.WInputMethod.openCandidateWindow(Native Method)
    at sun.awt.windows.WInputMethod.access$400(WInputMethod.java:45)
    at sun.awt.windows.WInputMethod$1.run(WInputMethod.java:602)
    at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311)
    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:80)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:90)
    at java.awt.EventQueue$4.run(EventQueue.java:733)
    at java.awt.EventQueue$4.run(EventQueue.java:731)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:730)
    at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:159) [catch]
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:205)    
    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)

版本信息

Answer 1

您的例子很少。 它可能缺少某些屬性。 試試看：

package finalmodel;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;

public class FinalModel extends JFrame {
 public FinalModel () {
   setTitle("setTitle()");
   setSize(300, 200);
   setLocationRelativeTo(null);
   setDefaultCloseOperation(EXIT_ON_CLOSE);
 }
 public static void main(String[] args) {
   FinalModel fm = new FinalModel ();
   fm.setVisible(true);
 }
}

這是一篇關於jframe的好文章，用於實踐jframe

Answer 2

Netbeans錯誤！ 用未更新的版本或類似的方法重新安裝Netbeans。