app crashes after button clicked with empty edit text

Question

Hi dears! I need your help( please help me solve the problem.

app crashes after button clicked with empty edit text ((

I cant solve this porblem. I added this operator IF : if (etText.getText().toString().trim().length()> 0) But its not solve the problem.

I have a little development experience and this code I watched from the lesson in YouTube

I will be very happy if you help me, sorry for the large amount of code

    public class DriverLoginActivity extends AppCompatActivity {
    private EditText mEmail, mPassword;
    private Button mLogin, mRegistration;

    private FirebaseAuth mAuth;
    private FirebaseAuth.AuthStateListener firebaseAuthListener;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_driver_login);  

        mAuth = FirebaseAuth.getInstance();

        firebaseAuthListener = new FirebaseAuth.AuthStateListener() {
            @Override
            public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
                FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();    

                if(user!=null){
                    Intent intent = new Intent(DriverLoginActivity.this, MapActivity.class);
                    startActivity(intent);
                    finish();
                    return;
                }
            }
        };

        mEmail = (EditText) findViewById(R.id.email);
        mPassword = (EditText) findViewById(R.id.password);
        mLogin = (Button) findViewById(R.id.login);
        mRegistration = (Button) findViewById(R.id.registration);

        mRegistration.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (mEmail.getText().toString().trim().length()< 0)
                    if (mPassword.getText().toString().trim().length()< 0);

                final String email = mEmail.getText().toString();
                final String password = mPassword.getText().toString();

                mAuth.createUserWithEmailAndPassword(email, password).addOnCompleteListener(DriverLoginActivity.this, new OnCompleteListener<AuthResult>() {
                    @Override
                    public void onComplete(@NonNull Task<AuthResult> task) {
                        if(!task.isSuccessful() ){
                            Toast.makeText(DriverLoginActivity.this, "sign up error", Toast.LENGTH_SHORT).show();    
                        }else{
                            String user_id = mAuth.getCurrentUser().getUid();
                            DatabaseReference current_user_db = FirebaseDatabase.getInstance().getReference().child("Users").child("Riders").child(user_id);
                            current_user_db.setValue(true);
                        }
                    }
                });
            }
        });

        mLogin.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                final String email = mEmail.getText().toString();
                final String password = mPassword.getText().toString();
                mAuth.signInWithEmailAndPassword(email, password).addOnCompleteListener(DriverLoginActivity.this, new OnCompleteListener<AuthResult>() {
                    @Override
                    public void onComplete(@NonNull Task<AuthResult> task) {
                        if(!task.isSuccessful()){
                            Toast.makeText(DriverLoginActivity.this, "sign in error", Toast.LENGTH_SHORT).show();
                        }
                    }
                });
            }
        });
    }

    @Override
    protected void onStart() {
        super.onStart();
        mAuth.addAuthStateListener(firebaseAuthListener);
    }

    @Override
    protected void onStop() {
        super.onStop();
        mAuth.removeAuthStateListener(firebaseAuthListener);
    }
  }
}

In your code I cannot find anywhere the: `etText.getText().toString().trim().length()> 0`!?!? Only relevant are: 1) `if (mEmail.getText().toString().trim().length()< 0)` and 2) `if (mPassword.getText().toString().trim().length()< 0);` — pleft, Oct 25 '17 at 11:27
https://stackoverflow.com/questions/27086808/android-check-null-or-empty-string-in-android — IntelliJ Amiya, Oct 25 '17 at 11:33

score 1 · Accepted Answer · answered Oct 25 '17 at 11:34

I think these lines of code are a bit confusing, plus you are not checking for null pointer exception in mEmail.getText(), so calling mEmail.getText().toString() will probably cause a NullPointerException to be thrown and crash your application (in case you send empty text).

 if (mEmail.getText().toString().trim().length()< 0)
                if (mPassword.getText().toString().trim().length()< 0);
 final String email = mEmail.getText().toString();
            final String password = mPassword.getText().toString();

It should be:

 if ((mEmail.getText() != null && mEmail.getText().toString().trim().length() > 0 ) && (mPassword.getText() != null && mPassword.getText().toString().trim().length() > 0)) {

    final String email = mEmail.getText().toString();
    final String password = mPassword.getText().toString();
    // rest of your code below
}

Thank you very much you helped me a lot! – Rustam Ismayilov Oct 25 '17 at 12:41 — Rustam Ismayilov, Oct 25 '17 at 12:41

score 0 · Answer 2 · answered Oct 25 '17 at 11:34

The fields might not be correctly set:

mEmail = (EditText) findViewById(R.id.email);
mPassword = (EditText) findViewById(R.id.password);

Check with the debugger that both these vars are not null. If they are null, you probably have a problem in the layout file activity_driver_login.xml. Maybe there is no edit texts with is email or password.

score 0 · Answer 3 · answered Oct 25 '17 at 11:46

Error is that in your second if condition at the end you are using ; and the conditions should be opposite. Check this code

public class DriverLoginActivity extends AppCompatActivity {
    private EditText mEmail, mPassword;
    private Button mLogin, mRegistration;

    private FirebaseAuth mAuth;
    private FirebaseAuth.AuthStateListener firebaseAuthListener;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_driver_login);

        mAuth = FirebaseAuth.getInstance();

        firebaseAuthListener = new FirebaseAuth.AuthStateListener() {
            @Override
            public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
                FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();
                if(user!=null){
                    Intent intent = new Intent(DriverLoginActivity.this, MapActivity.class);
                    startActivity(intent);
                    finish();
                    return;
                }
            }
        };
        mEmail = (EditText) findViewById(R.id.email);
        mPassword = (EditText) findViewById(R.id.password);
        mLogin = (Button) findViewById(R.id.login);
        mRegistration = (Button) findViewById(R.id.registration);
        mRegistration.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (!mEmail.getText().toString().isEmpty() && !mPassword.getText().toString().isEmpty())
                    if (mPassword.getText().toString().trim().length()> 0 && mEmail.getText().toString().trim().length()> 0 ){
                        final String email = mEmail.getText().toString();
                        final String password = mPassword.getText().toString();
                        mAuth.createUserWithEmailAndPassword(email, password).addOnCompleteListener(DriverLoginActivity.this, new OnCompleteListener<AuthResult>() {
                            @Override
                            public void onComplete(@NonNull Task<AuthResult> task) {
                                if(!task.isSuccessful() ){
                                    Toast.makeText(DriverLoginActivity.this, "sign up error", Toast.LENGTH_SHORT).show();
                                }else{
                                    String user_id = mAuth.getCurrentUser().getUid();
                                    DatabaseReference current_user_db = FirebaseDatabase.getInstance().getReference().child("Users").child("Riders").child(user_id);
                                    current_user_db.setValue(true);
                                }
                            }
                        });
                    }
                }
            });
        mLogin.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                final String email = mEmail.getText().toString();
                final String password = mPassword.getText().toString();
                mAuth.signInWithEmailAndPassword(email, password).addOnCompleteListener(DriverLoginActivity.this, new OnCompleteListener<AuthResult>() {
                    @Override
                    public void onComplete(@NonNull Task<AuthResult> task) {
                        if(!task.isSuccessful()){
                            Toast.makeText(DriverLoginActivity.this, "sign in error", Toast.LENGTH_SHORT).show();
                        }
                    }
                });

            }
        });
    }


    @Override
    protected void onStart() {
        super.onStart();
        mAuth.addAuthStateListener(firebaseAuthListener);
    }
    @Override
    protected void onStop() {
        super.onStop();
        mAuth.removeAuthStateListener(firebaseAuthListener);
    }
}

app crashes after button clicked with empty edit text

3 Answers3