My application getting crashes even though there is no error while building the app

Question

In button save my application is getting crashed.
Please help me out with this issue.

 @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login_info);

    ref = FirebaseDatabase.getInstance().getReference().child("Member");

    btnSave.setOnClickListener(new View.OnClickListener() { 
            @Override
            public void onClick(View view) {
                member.setUserName(name1.getText().toString().trim());
                member.setFirstName(name2.getText().toString().trim());
                member.setLastName(name3.getText().toString().trim());
                member.setEmail(name4.getText().toString().trim());
                ref.push().setValue("member");
                Toast.makeText(LoginInfo.this,"data Inserted Sucessfully",Toast.LENGTH_LONG).show();
            }
        });

Log Error

E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.firebasesign, PID: 20460 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.firebasesign/com.example.firebasesign.LoginInfo}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.view.View.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$MethodAndArgsCaller.run(ZygoteInit.java:867) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:757) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.view.View.setOnClickListener(android.view.View$OnClickListener)' on a null object reference at com.example.firebasesign.LoginInfo.onCreate(LoginInfo.java:34) 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)

You forgot to assign `btnSave` before calling `setOnClickListener()` on it. That is, you forgot `btnSave = findViewById(R.id.your_button_id);`, after the `setContentView()` call. — Mike M., Apr 18 '19 at 22:46

score 1 · Accepted Answer · answered Apr 18 '19 at 22:46

Based on your log the btnSave object is null. You will need to get a reference to the object by calling findViewById prior to attempting to setOnClickListener()

 btnSave = findViewById(R.id.yourButtonId)

Where yourButtonId is the id that you set on the xml item

 <Button
        android:id="@+id/yourButtonId"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>

If you are using Butter Knife don't forget to add

  ButterKnife.bind(this);

to your onCreate() method

My application getting crashes even though there is no error while building the app

1 Answers1