java.lang.String android.content.Context.getString(int)' on a null object reference

content没有实例化,在Activity的onCreate中搞一下即可:



``` FATAL EXCEPTION: main Process: com.oem.qisda, PID: 9507 java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.oem.qisda/com.oem.qisda.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.content.Context.getPackageName()' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3690) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3923) at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:103) at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:139) at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:96) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2444) at android.os.Handler.dispatchMessage(Handler.java:106) at android.os.Looper.loopOnce(Looper.java:205) at android.os.Looper.loop(Looper.java:294) at android.app.ActivityThread.main(ActivityThread.java:8223) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:685) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:977) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.content.Context.getPackageName()' on a null object reference at android.content.ContextWrapper.getPackageName(ContextWrapper.java:177) at com.oem.qisda.MainActivity.<init>(MainActivity.java:57) at java.lang.Class.newInstance(Native Method) at android.app.AppComponentFactory.instantiateActivity(AppComponentFactory.java:95) at androidx.core.app.CoreComponentFactory.instantiateActivity(CoreComponentFactory.java:44) at android.app.Instrumentation.newActivity(Instrumentation.java:1379) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3677) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3923)  at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:103)  at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:139)  at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:96)  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2444)  at android.os.Handler.dispatchMessage(Handler.java:106)  at android.os.Looper.loopOnce(Looper.java:205)  at android.os.Looper.loop(Looper.java:294)  at android.app.ActivityThread.main(ActivityThread.java:8223)  at java.lang.reflect.Method.invoke(Native Method)  at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:685)  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:977)```解决?
最新发布
03-14
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