Question

所以我在几个月前重新制作我的应用程序（把故障排除在外，并使一些事情变得更好）但是现在我想出了一个我没找到的问题而且不知道它是什么是。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)

有人能指出我需要看到错误的方向吗？

Answer 1

从logcat看来，你调用的方法似乎是

 PreferenceManager.getDefaultSharedPreferences(context);

如果此处的上下文为null，则可能存在此类异常。因此，尝试将有效的上下文作为参数传递。你可以使用以下方法。

Context context = getApplicationContext();

启动时PreferenceManager.getDefaultSharedPreferences的NullPointerException

1 个答案: