I was working on Android Studio. I had encountered a situation where the app is getting stopped. Please help anyone : 01-12 10:35:55.620 6865-6865/? I/zygote: Not late-enabling -Xcheck:jni (already on)
01-12 10:35:55.720 6865-6865/? W/zygote: Unexpected CPU variant for X86 using defaults: x86
01-12 10:35:57.100 6865-6865/c.mycompany.cart D/FirebaseApp: com.google.firebase.auth.FirebaseAuth is not linked. Skipping initialization.
01-12 10:35:57.162 6865-6865/c.mycompany.cart D/FirebaseApp: com.google.firebase.crash.FirebaseCrash is not linked. Skipping initialization.
01-12 10:35:57.456 6865-6865/c.mycompany.cart I/FA: App measurement is starting up, version: 10298
01-12 10:35:57.456 6865-6865/c.mycompany.cart I/FA: To enable debug logging run: adb shell setprop log.tag.FA VERBOSE
01-12 10:35:57.547 6865-6877/c.mycompany.cart I/zygote: Background concurrent copying GC freed 10976(2MB) AllocSpace objects, 2(40KB) LOS objects, 75% free, 499KB/2035KB, paused 1.257ms total 117.358ms
01-12 10:35:57.561 6865-6865/c.mycompany.cart V/FA: Collection enabled
01-12 10:35:57.561 6865-6865/c.mycompany.cart V/FA: App package, google app id: c.mycompany.cart, 1:974188279777:android:324d0d4ee5746a21
01-12 10:35:57.562 6865-6865/c.mycompany.cart I/FA: To enable faster debug mode event logging run:
                                                      adb shell setprop debug.firebase.analytics.app c.mycompany.cart
01-12 10:35:57.562 6865-6865/c.mycompany.cart D/FA: Debug-level message logging enabled
01-12 10:35:57.679 6865-6865/c.mycompany.cart V/FA: Registered activity lifecycle callback
01-12 10:35:57.737 6865-6865/c.mycompany.cart I/FirebaseInitProvider: FirebaseApp initialization successful
01-12 10:35:57.878 6865-6918/c.mycompany.cart V/FA: Using measurement service
01-12 10:35:57.962 6865-6918/c.mycompany.cart V/FA: Connecting to remote service
01-12 10:35:57.971 6865-6865/c.mycompany.cart I/InstantRun: starting instant run server: is main process
01-12 10:35:58.215 6865-6865/c.mycompany.cart V/FA: onActivityCreated
01-12 10:35:58.564 6865-6918/c.mycompany.cart V/FA: Using measurement service
01-12 10:35:58.564 6865-6918/c.mycompany.cart V/FA: Connection attempt already in progress
01-12 10:35:58.568 6865-6918/c.mycompany.cart V/FA: Activity resumed, time: 833843
01-12 10:35:58.569 6865-6877/c.mycompany.cart I/zygote: NativeAllocBackground concurrent copying GC freed 2132(544KB) AllocSpace objects, 3(60KB) LOS objects, 66% free, 767KB/2MB, paused 987us total 155.056ms
01-12 10:35:58.646 6865-6941/c.mycompany.cart D/OpenGLRenderer: HWUI GL Pipeline
01-12 10:35:58.715 6865-6941/c.mycompany.cart I/OpenGLRenderer: Initialized EGL, version 1.4
01-12 10:35:58.715 6865-6941/c.mycompany.cart D/OpenGLRenderer: Swap behavior 1
01-12 10:35:58.753 6865-6941/c.mycompany.cart D/EGL_emulation: eglCreateContext: 0xa8c852a0: maj 2 min 0 rcv 2
01-12 10:35:58.832 6865-6941/c.mycompany.cart D/EGL_emulation: eglMakeCurrent: 0xa8c852a0: ver 2 0 (tinfo 0xa8c83370)
01-12 10:35:59.057 6865-6941/c.mycompany.cart D/EGL_emulation: eglMakeCurrent: 0xa8c852a0: ver 2 0 (tinfo 0xa8c83370)
01-12 10:35:59.847 6865-6865/c.mycompany.cart I/Choreographer: Skipped 47 frames!  The application may be doing too much work on its main thread.
01-12 10:35:59.850 6865-6918/c.mycompany.cart D/FA: Connected to remote service
01-12 10:35:59.850 6865-6918/c.mycompany.cart V/FA: Processing queued up service tasks: 2
01-12 10:36:03.438 6865-6918/c.mycompany.cart V/FA: Session started, time: 838718
01-12 10:36:03.462 6865-6918/c.mycompany.cart I/FA: Tag Manager is not found and thus will not be used
01-12 10:36:03.465 6865-6918/c.mycompany.cart D/FA: Logging event (FE): _s, Bundle[{_o=auto, _sc=MainActivity, _si=7685968590249170324}]
01-12 10:36:04.148 6865-6918/c.mycompany.cart V/FA: Recording user engagement, ms: 5584
01-12 10:36:04.167 6865-6918/c.mycompany.cart V/FA: Activity paused, time: 839425
01-12 10:36:04.292 6865-6918/c.mycompany.cart D/FA: Logging event (FE): _e, Bundle[{_o=auto, _et=5584, _sc=MainActivity, _si=7685968590249170324}]
01-12 10:36:04.454 6865-6865/c.mycompany.cart V/FA: onActivityCreated
01-12 10:36:04.873 6865-6865/c.mycompany.cart I/DynamiteModule: Considering local module com.google.android.gms.firebase_database:4 and remote module com.google.android.gms.firebase_database:6
01-12 10:36:04.874 6865-6865/c.mycompany.cart I/DynamiteModule: Selected remote version of com.google.android.gms.firebase_database, version >= 6
01-12 10:36:08.100 6865-6865/c.mycompany.cart W/zygote: Skipping duplicate class check due to unrecognized classloader
01-12 10:36:19.178 6865-6918/c.mycompany.cart V/FA: Activity resumed, time: 854452
01-12 10:36:19.281 6865-6865/c.mycompany.cart I/Choreographer: Skipped 893 frames!  The application may be doing too much work on its main thread.
01-12 10:36:19.532 6865-7102/c.mycompany.cart D/NetworkSecurityConfig: No Network Security Config specified, using platform default
01-12 10:36:19.612 6865-6941/c.mycompany.cart D/EGL_emulation: eglMakeCurrent: 0xa8c852a0: ver 2 0 (tinfo 0xa8c83370)
01-12 10:36:21.155 6865-6865/c.mycompany.cart I/Choreographer: Skipped 93 frames!  The application may be doing too much work on its main thread.
01-12 10:36:21.375 6865-6865/c.mycompany.cart W/View: dispatchProvideAutofillStructure(): not laid out, ignoring
01-12 10:36:21.385 6865-6865/c.mycompany.cart I/AssistStructure: Flattened final assist data: 2000 bytes, containing 1 windows, 7 views
01-12 10:36:23.361 6865-6871/c.mycompany.cart I/zygote: Do partial code cache collection, code=29KB, data=28KB
01-12 10:36:23.361 6865-6871/c.mycompany.cart I/zygote: After code cache collection, code=29KB, data=28KB
01-12 10:36:23.361 6865-6871/c.mycompany.cart I/zygote: Increasing code cache capacity to 128KB
01-12 10:36:24.212 6865-6918/c.mycompany.cart V/FA: Inactivity, disconnecting from the service
01-12 10:36:33.385 6865-6871/c.mycompany.cart I/zygote: Do partial code cache collection, code=60KB, data=57KB
01-12 10:36:33.385 6865-6871/c.mycompany.cart I/zygote: After code cache collection, code=60KB, data=57KB
01-12 10:36:33.387 6865-6871/c.mycompany.cart I/zygote: Increasing code cache capacity to 256KB
01-12 10:36:44.043 6865-6871/c.mycompany.cart I/zygote: Do full code cache collection, code=110KB, data=107KB
01-12 10:36:44.044 6865-6871/c.mycompany.cart I/zygote: After code cache collection, code=89KB, data=69KB
01-12 10:37:10.618 6865-6871/c.mycompany.cart I/zygote: Do partial code cache collection, code=121KB, data=95KB
01-12 10:37:10.618 6865-6871/c.mycompany.cart I/zygote: After code cache collection, code=121KB, data=95KB
01-12 10:37:10.618 6865-6871/c.mycompany.cart I/zygote: Increasing code cache capacity to 512KB
01-12 10:37:16.309 6865-6871/c.mycompany.cart I/zygote: JIT allocated 56KB for compiled code of void android.view.View.<init>(android.content.Context, android.util.AttributeSet, int, int)
01-12 10:37:16.428 6865-6941/c.mycompany.cart D/EGL_emulation: eglMakeCurrent: 0xa8c852a0: ver 2 0 (tinfo 0xa8c83370)
01-12 10:37:17.119 6865-6941/c.mycompany.cart D/EGL_emulation: eglMakeCurrent: 0xa8c852a0: ver 2 0 (tinfo 0xa8c83370)
01-12 10:37:17.136 6865-6865/c.mycompany.cart I/Choreographer: Skipped 42 frames!  The application may be doing too much work on its main thread.
01-12 10:37:17.279 6865-6941/c.mycompany.cart D/EGL_emulation: eglMakeCurrent: 0xa8c852a0: ver 2 0 (tinfo 0xa8c83370)
01-12 10:37:17.795 6865-6941/c.mycompany.cart D/EGL_emulation: eglMakeCurrent: 0xa8c852a0: ver 2 0 (tinfo 0xa8c83370)
01-12 10:37:17.950 6865-6865/c.mycompany.cart W/ClassMapper: No setter/field for Name found on class c.mycompany.cart.Model.User (fields/setters are case sensitive!)
01-12 10:37:17.951 6865-6865/c.mycompany.cart W/ClassMapper: No setter/field for Password found on class c.mycompany.cart.Model.User (fields/setters are case sensitive!)
01-12 10:37:17.951 6865-6865/c.mycompany.cart D/AndroidRuntime: Shutting down VM
                                                                
                                                                
                                                                --------- beginning of crash
01-12 10:37:17.953 6865-6865/c.mycompany.cart E/AndroidRuntime: FATAL EXCEPTION: main
                                                                Process: c.mycompany.cart, PID: 6865
                                                                java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference
                                                                    at c.mycompany.cart.SignIn$1$1.onDataChange(SignIn.java:63)
                                                                    at com.google.android.gms.internal.zzbpx.zza(Unknown Source:13)
                                                                    at com.google.android.gms.internal.zzbqx.zzZS(Unknown Source:2)
                                                                    at com.google.android.gms.internal.zzbra$1.run(Unknown Source:63)
                                                                    at android.os.Handler.handleCallback(Handler.java:789)
                                                                    at android.os.Handler.dispatchMessage(Handler.java:98)
                                                                    at android.os.Looper.loop(Looper.java:164)
                                                                    at android.app.ActivityThread.main(ActivityThread.java:6541)
                                                                    at java.lang.reflect.Method.invoke(Native Method)
                                                                    at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
                                                                    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)


Here is the logcat. Can anyone help me please?