4

所以我正在重新制作几个月前的应用程序（找出错误，并让一些事情变得更好）但现在我遇到了一个我没有找到并且不知道它是什么的问题。如果我在手机上运行应用程序，则会出现此错误

01-20 22:37:46.595: E/AndroidRuntime(7350): FATAL EXCEPTION: main
01-20 22:37:46.595: E/AndroidRuntime(7350): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.stevedc.thinklogic/com.stevedc.thinklogic.TowerHanoi}: java.lang.NullPointerException
01-20 22:37:46.595: E/AndroidRuntime(7350):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1891)
01-20 22:37:46.595: E/AndroidRuntime(7350):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1992)
01-20 22:37:46.595: E/AndroidRuntime(7350):     at android.app.ActivityThread.access$600(ActivityThread.java:127)
01-20 22:37:46.595: E/AndroidRuntime(7350):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1158)
01-20 22:37:46.595: E/AndroidRuntime(7350):     at android.os.Handler.dispatchMessage(Handler.java:99)
01-20 22:37:46.595: E/AndroidRuntime(7350):     at android.os.Looper.loop(Looper.java:137)
01-20 22:37:46.595: E/AndroidRuntime(7350):     at android.app.ActivityThread.main(ActivityThread.java:4441)
01-20 22:37:46.595: E/AndroidRuntime(7350):     at java.lang.reflect.Method.invokeNative(Native Method)
01-20 22:37:46.595: E/AndroidRuntime(7350):     at java.lang.reflect.Method.invoke(Method.java:511)
01-20 22:37:46.595: E/AndroidRuntime(7350):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
01-20 22:37:46.595: E/AndroidRuntime(7350):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
01-20 22:37:46.595: E/AndroidRuntime(7350):     at dalvik.system.NativeStart.main(Native Method)
01-20 22:37:46.595: E/AndroidRuntime(7350): Caused by: java.lang.NullPointerException
01-20 22:37:46.595: E/AndroidRuntime(7350):     at android.preference.PreferenceManager.getDefaultSharedPreferencesName(PreferenceManager.java:371)
01-20 22:37:46.595: E/AndroidRuntime(7350):     at android.preference.PreferenceManager.getDefaultSharedPreferences(PreferenceManager.java:366)
01-20 22:37:46.595: E/AndroidRuntime(7350):     at com.stevedc.thinklogic.TowerHanoi.<init>(TowerHanoi.java:42)
01-20 22:37:46.595: E/AndroidRuntime(7350):     at java.lang.Class.newInstanceImpl(Native Method)
01-20 22:37:46.595: E/AndroidRuntime(7350):     at java.lang.Class.newInstance(Class.java:1319)
01-20 22:37:46.595: E/AndroidRuntime(7350):     at android.app.Instrumentation.newActivity(Instrumentation.java:1023)
01-20 22:37:46.595: E/AndroidRuntime(7350):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1882)

有人可以指出我需要查看故障所在的方向吗？

4

1 回答 1

14

从logcat看来，您调用的方法是

 PreferenceManager.getDefaultSharedPreferences(context);

如果这里的上下文为空，那么就有可能出现这种异常。所以尝试传递一个有效的上下文作为参数。您可以使用以下方法。

Context context = getApplicationContext();
于 2013-01-21T06:18:57.617 回答