安卓报错：java.lang.RuntimeException: Unable to start activity ComponentInfo---getSupportActionBar()为null
16lz
2021-12-04
报错信息：
E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.edm, PID: 16919 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.edm/com.example.edm.StudentActivity.TimeTable.ui.editcourse.EditActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void androidx.appcompat.app.ActionBar.setDisplayHomeAsUpEnabled(boolean)' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3773) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3952) at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:91) at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:149) at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:103) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2386) at android.os.Handler.dispatchMessage(Handler.java:107) at android.os.Looper.loop(Looper.java:213) at android.app.ActivityThread.main(ActivityThread.java:8169) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:513) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1101) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void androidx.appcompat.app.ActionBar.setDisplayHomeAsUpEnabled(boolean)' on a null object reference at com.example.edm.StudentActivity.TimeTable.ui.editcourse.EditActivity.setActionBar(EditActivity.java:248) at com.example.edm.StudentActivity.TimeTable.ui.editcourse.EditActivity.onCreate(EditActivity.java:75) at android.app.Activity.performCreate(Activity.java:8086) at android.app.Activity.performCreate(Activity.java:8074) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1313) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3746) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3952) at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:91) at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:149) at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:103) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2386) at android.os.Handler.dispatchMessage(Handler.java:107) at android.os.Looper.loop(Looper.java:213) at android.app.ActivityThread.main(ActivityThread.java:8169) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:513) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1101) 错误原因：
private void setActionBar() { ActionBar actionBar = getSupportActionBar(); actionBar.setDisplayHomeAsUpEnabled(true); actionBar.setTitle(R.string.course_edit); }代码中actionBar为空指针。
解决方案：检查AndroidManifest.xml文件中相关Activity的theme是否为:
android:theme="@style/Theme.AppCompat.Light.NoActionBar"将其改为：
android:theme="@style/Theme.AppCompat"更多相关文章
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