【问题标题】:NullPointerException thrown on listview creation创建列表视图时引发 NullPointerException
【发布时间】:2011-07-16 11:55:53
【问题描述】:

我已经查看了logcat,发现了错误,但不知道如何修复它......

来源:

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    ListView lv = getListView();
    lv.setTextFilterEnabled(true);

    lv.setOnItemClickListener(new OnItemClickListener() {
      public void onItemClick(AdapterView<?> parent, View view,
          int position, long id) {
        // When clicked, show a toast with the TextView text
        Toast.makeText(getApplicationContext(), ((TextView) view).getText(),
            Toast.LENGTH_SHORT).show();
      }
    });
    File root = new File(Environment.getExternalStorageDirectory(), "Notes");
    if (!root.exists()) {
        root.mkdirs();
    }
    String[] filez = root.list();
    setListAdapter(new ArrayAdapter<String>(this, R.layout.list_item, filez));
}

}

Logcat:

    07-16 03:52:27.571: WARN/KeyCharacterMap(373): No keyboard for id 0
07-16 03:52:27.571: WARN/KeyCharacterMap(373): Using default keymap: /system/usr/keychars/qwerty.kcm.bin
07-16 03:52:29.000: DEBUG/AndEngine(373): UpdateThread interrupted. Don't worry - this Exception is most likely expected!
07-16 03:52:29.000: DEBUG/AndEngine(373): java.lang.InterruptedException
07-16 03:52:29.000: DEBUG/AndEngine(373):     at java.lang.Object.wait(Native Method)
07-16 03:52:29.000: DEBUG/AndEngine(373):     at java.lang.Object.wait(Object.java:288)
07-16 03:52:29.000: DEBUG/AndEngine(373):     at org.anddev.andengine.engine.Engine$State.waitUntilCanUpdate(Engine.java:712)
07-16 03:52:29.000: DEBUG/AndEngine(373):     at org.anddev.andengine.engine.Engine.yieldDraw(Engine.java:462)
07-16 03:52:29.000: DEBUG/AndEngine(373):     at org.anddev.andengine.engine.Engine.onTickUpdate(Engine.java:451)
07-16 03:52:29.000: DEBUG/AndEngine(373):     at org.anddev.andengine.engine.Engine$UpdateThread.run(Engine.java:675)
07-16 03:52:29.170: INFO/Ads(373): adRequestUrlHtml: <html><head><script src="http://www.gstatic.com/afma/sdk-core-v40.js"></script><script>AFMA_buildAdURL({"preqs":0,"u_sd":1,"slotname":"a14e19658c1630b","u_w":320,"msid":"com.momentum.xpad","simulator":1,"cap":"m,a","js":"afma-sdk-a-v4.1.0","isu":"B3EEABB8EE11C2BE770B684D95219ECB","format":"320x50_mb","net":"ed","app_name":"1.android.com.momentum.xpad","hl":"en","u_h":480,"u_audio":4,"u_so":"p"});</script></head><body></body></html>
07-16 03:52:29.280: INFO/ActivityManager(58): Displayed activity com.momentum.xpad/.main: 3183 ms (total 3183 ms)
07-16 03:52:29.561: WARN/InputManagerService(58): Window already focused, ignoring focus gain of: com.android.internal.view.IInputMethodClient$Stub$Proxy@43f3dab8
07-16 03:52:31.121: INFO/ActivityManager(58): Starting activity: Intent { cmp=com.momentum.xpad/.folders }
07-16 03:52:31.321: DEBUG/AndroidRuntime(373): Shutting down VM
07-16 03:52:31.321: WARN/dalvikvm(373): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
07-16 03:52:31.381: ERROR/AndroidRuntime(373): FATAL EXCEPTION: main
07-16 03:52:31.381: ERROR/AndroidRuntime(373): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.momentum.xpad/com.momentum.xpad.folders}: java.lang.NullPointerException
07-16 03:52:31.381: ERROR/AndroidRuntime(373):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
07-16 03:52:31.381: ERROR/AndroidRuntime(373):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
07-16 03:52:31.381: ERROR/AndroidRuntime(373):     at android.app.ActivityThread.access$2300(ActivityThread.java:125)
07-16 03:52:31.381: ERROR/AndroidRuntime(373):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
07-16 03:52:31.381: ERROR/AndroidRuntime(373):     at android.os.Handler.dispatchMessage(Handler.java:99)
07-16 03:52:31.381: ERROR/AndroidRuntime(373):     at android.os.Looper.loop(Looper.java:123)
07-16 03:52:31.381: ERROR/AndroidRuntime(373):     at android.app.ActivityThread.main(ActivityThread.java:4627)
07-16 03:52:31.381: ERROR/AndroidRuntime(373):     at java.lang.reflect.Method.invokeNative(Native Method)
07-16 03:52:31.381: ERROR/AndroidRuntime(373):     at java.lang.reflect.Method.invoke(Method.java:521)
07-16 03:52:31.381: ERROR/AndroidRuntime(373):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
07-16 03:52:31.381: ERROR/AndroidRuntime(373):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
07-16 03:52:31.381: ERROR/AndroidRuntime(373):     at dalvik.system.NativeStart.main(Native Method)
07-16 03:52:31.381: ERROR/AndroidRuntime(373): Caused by: java.lang.NullPointerException
07-16 03:52:31.381: ERROR/AndroidRuntime(373):     at java.util.Arrays$ArrayList.<init>(Arrays.java:49)
07-16 03:52:31.381: ERROR/AndroidRuntime(373):     at java.util.Arrays.asList(Arrays.java:171)
07-16 03:52:31.381: ERROR/AndroidRuntime(373):     at android.widget.ArrayAdapter.<init>(ArrayAdapter.java:125)
07-16 03:52:31.381: ERROR/AndroidRuntime(373):     at com.momentum.xpad.folders.onCreate(folders.java:42)
07-16 03:52:31.381: ERROR/AndroidRuntime(373):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
07-16 03:52:31.381: ERROR/AndroidRuntime(373):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
07-16 03:52:31.381: ERROR/AndroidRuntime(373):     ... 11 more
07-16 03:52:31.411: WARN/ActivityManager(58):   Force finishing activity com.momentum.xpad/.folders
07-16 03:52:31.421: WARN/ActivityManager(58):   Force finishing activity com.momentum.xpad/.main
07-16 03:52:31.921: WARN/ActivityManager(58): Activity pause timeout for HistoryRecord{43f5f618 com.momentum.xpad/.folders}
07-16 03:52:33.101: INFO/Process(373): Sending signal. PID: 373 SIG: 9
07-16 03:52:33.141: INFO/ActivityManager(58): Process com.momentum.xpad (pid 373) has died.
07-16 03:52:33.151: INFO/WindowManager(58): WIN DEATH: Window{43fa1368 com.momentum.xpad/com.momentum.xpad.main paused=true}
07-16 03:52:33.191: WARN/InputManagerService(58): Got RemoteException sending setActive(false) notification to pid 373 uid 10033
07-16 03:52:37.991: DEBUG/dalvikvm(266): GC_EXPLICIT freed 249 objects / 11840 bytes in 146ms
07-16 03:52:42.542: WARN/ActivityManager(58): Activity destroy timeout for HistoryRecord{43f5adb8 com.momentum.xpad/.main}
07-16 03:52:42.542: WARN/ActivityManager(58): Activity destroy timeout for HistoryRecord{43f5f618 com.momentum.xpad/.folders}

任何帮助将不胜感激...

【问题讨论】:

    标签: android


    【解决方案1】:

    我希望你的R.layout.folders 是问题所在。

    在示例中我看到:R.layout.list_item,在我的 Spinner 中我使用 android.R.layout.simple_spinner_item,因此您可能只想进行第一次更改,看看是否能解决您的问题。

    这个问题涉及使用R.layout.list_item,顺便说一句:

    Android there is no ListView adapter resourceId

    【讨论】:

    • 谢谢!按照您提供的链接解决了我的问题!感谢您从字面上保存我的应用程序...
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