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當我嘗試運行我的應用程序我碰到下面的錯誤,我只得到了這些錯誤一旦實施和expandablelistview:E/AndroidRuntime:致命異常:主。 ExpadableListView Isses
7686/com.example.admin.n0499049 E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.admin.n0499049, PID: 7686
java.lang.RuntimeException: Unable to start activity ComponentInfo { com.example.admin.n0499049/com.example.admin.n0499049.MainActivity }: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ExpandableListView.setAdapter(android.widget.ExpandableListAdapter)'
on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java: 2665)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java: 2726)
at android.app.ActivityThread. - wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java: 1477)
at android.os.Handler.dispatchMessage(Handler.java: 102)
at android.os.Looper.loop(Looper.java: 154)
at android.app.ActivityThread.main(ActivityThread.java: 6119)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java: 886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java: 776)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ExpandableListView.setAdapter(android.widget.ExpandableListAdapter)'
on a null object reference
at com.example.admin.n0499049.MainActivity.onCreate(MainActivity.java: 34)
at android.app.Activity.performCreate(Activity.java: 6679)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java: 1118)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java: 2618)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java: 2726)
at android.app.ActivityThread. - wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java: 1477)
at android.os.Handler.dispatchMessage(Handler.java: 102)
at android.os.Looper.loop(Looper.java: 154)
at android.app.ActivityThread.main(ActivityThread.java: 6119)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java: 886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java: 776)
我怎麼做發起了正確的方法是什麼?我是新開發的android。 – user7731456
http://www.vogella.com/tutorials/AndroidListView/article.html – Minis
謝謝,我看了一下鏈接。因爲我是新來的android開發,我不明白我做錯了什麼。如果我把你的項目寄給你,你能看看它嗎? – user7731456