[Java] Questions about Android studio.

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I am creating my own android application, but it is repeatedly stopped even when I start the application, and it does not work well I confirmed Logcat, but it is displayed as follows. ,It is not well understood. How can I fix it?

2020-07-10 22:39:52.674 17730-17730/? E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.fumemo, PID: 17730 java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.fumemo/com.example.fumemo.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method’android.content.pm.ApplicationInfo android.content. Context.getApplicationInfo()’ on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3194) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3409) at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83) at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2016) at android.os.Handler.dispatchMessage(Handler.java:107) at android.os.Looper.loop(Looper.java:214) at android.app.ActivityThread.main(ActivityThread.java:7356) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method’android.content.pm.ApplicationInfo android.content.Context.getApplicationInfo()’ on a null object reference at android.content.ContextWrapper.getApplicationInfo(ContextWrapper.java:163) at android.view.ContextThemeWrapper.getTheme(ContextThemeWrapper.java:174) at android.content.Context.obtainStyledAttributes(Context.java:738) at androidx.appcompat.app.AppCompatDelegateImpl.createSubDecor(AppCompatDelegateImpl.java:692) at androidx.appcompat.app.AppCompatDelegateImpl.ensureSubDecor(AppCompatDelegateImpl.java:659) at androidx.appcompat.app.AppCompatDelegateImpl.findViewById(AppCompatDelegateImpl.java:479) at androidx.appcompat.app.AppCompatActivity.findViewById(AppCompatActivity.java:214) at com.example.fumemo.MainActivity.(MainActivity.java:35) at java.lang.Class.newInstance(Native Method) at android.app.AppComponentFactory.instantiateActivity(AppComponentFactory.java:95) at androidx.core.app.CoreComponentFactory.instantiateActivity(CoreComponentFactory.java:41) at android.app.Instrumentation.newActivity(Instrumentation.java:1250) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3182) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3409) at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83) at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2016) at android.os.Handler.dispatchMessage(Handler.java:107) at android.os.Looper.loop(Looper.java:214) at android.app.ActivityThread.main(ActivityThread.java:7356) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)