Caused by: java.lang.NullPointerException: Attempt to invoke virtual method ‘void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)’ on a null object reference at com.example.mylogin0310.LoginActivity.onCreate(LoginActivity.java:75)
问题描述:FATAL EXCEPTION: main
Process: com.example.mylogin0310, PID: 19367 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.mylogin0310/com.example.mylogin0310.LoginActivity}: java.lang.NullPointerException: Attempt to invoke virtual method ‘void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)’ on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2462) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2524) at android.app.ActivityThread.access800(ActivityThread.java:167)atandroid.app.ActivityThreadH.handleMessage(ActivityThread.java:1419) at android.os.Handler.dispatchMessage(Handler.java:111) at android.os.Looper.loop(Looper.java:194) at android.app.ActivityThread.main(ActivityThread.java:5546) at java.lang.reflect.Method.invoke(Native Method) at java.lang.reflect.Method.invoke(Method.java:372) at com.android.internal.os.ZygoteInitMethodAndArgsCaller.run(ZygoteInit.java:964)atcom.android.internal.os.ZygoteInit.main(ZygoteInit.java:759)Causedby:java.lang.NullPointerException:Attempttoinvokevirtualmethod′voidandroid.widget.Button.setOnClickListener(android.view.ViewOnClickListener)’ on a null object reference