Question

01-02 05:30:50.220 8776-8776/com.wordpress.alhazn.puhaba E/AndroidRuntime: FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.wordpress.alhazn.puhaba/com.wordpress.alhazn.puhaba.MainActivity}: java.lang.NullPointerException
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2045)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2146)
    at android.app.ActivityThread.access$700(ActivityThread.java:140)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1238)
    at android.os.Handler.dispatchMessage(Handler.java:99)
    at android.os.Looper.loop(Looper.java:177)
    at android.app.ActivityThread.main(ActivityThread.java:4944)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:511)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1038)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:805)
    at dalvik.system.NativeStart.main(Native Method)
 Caused by: java.lang.NullPointerException
    at android.support.v7.app.AppCompatDelegateImplBase.<init>(AppCompatDelegateImplBase.java:117)
    at android.support.v7.app.AppCompatDelegateImplV9.<init>(AppCompatDelegateImplV9.java:149)
    at android.support.v7.app.AppCompatDelegateImplV11.<init>(AppCompatDelegateImplV11.java:29)
    at android.support.v7.app.AppCompatDelegateImplV14.<init>(AppCompatDelegateImplV14.java:54)
    at android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:202)
    at android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:183)
    at android.support.v7.app.AppCompatActivity.getDelegate(AppCompatActivity.java:519)
    at android.support.v7.app.AppCompatActivity.findViewById(AppCompatActivity.java:190)
    at com.wordpress.alhazn.puhaba.MainActivity.<init>(MainActivity.java:44)
    at java.lang.Class.newInstanceImpl(Native Method)
    at java.lang.Class.newInstance(Class.java:1319)
    at android.app.Instrumentation.newActivity(Instrumentation.java:1068)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2036)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2146) 
    at android.app.ActivityThread.access$700(ActivityThread.java:140) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1238) 
    at android.os.Handler.dispatchMessage(Handler.java:99) 
    at android.os.Looper.loop(Looper.java:177) 
    at android.app.ActivityThread.main(ActivityThread.java:4944) 
    at java.lang.reflect.Method.invokeNative(Native Method) 
    at java.lang.reflect.Method.invoke(Method.java:511) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1038) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:805) 
    at dalvik.system.NativeStart.main(Native Method)

Answer 1

稍后在活动生命周期中移动findViewById()来电。不在<init>中，即构造函数/字段初始化，而是例如在您致电onCreate()之后setContentView()。

不幸的是我的应用已停止。 - 我的logcat

1 个答案: