로그 캣 메시지는이를 보여줍니다안드로이드 로그 고양이 오류
12-05 19:24:09.406 28495-28495/? E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.user.fragment, PID: 28495
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.user.fragment/com.example.user.fragment.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2659)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2724)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1473)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6123)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:757)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
at com.example.user.fragment.MainActivity.onCreate(MainActivity.java:25)
at android.app.Activity.performCreate(Activity.java:6672)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1140)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2612)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2724)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1473)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6123)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:757)
는 응용 프로그램이 갑자기 작동이 중지되었습니다. 가능한 오류는 무엇입니까?
[NullPointerException이란 무엇이며 어떻게 수정합니까?] (https://stackoverflow.com/questions/218384/what-is-a-nullpointerexception-and-how-do-i-fix -it) –
25 행의'MainActivity'에 초기화되지 않은'Button'이 아니라면'setOnClickListener'를하려고합니다. – Bek