Question

嗨亲爱的！我需要你的帮助（请帮我解决问题。

单击按钮并显示空文本后，

应用程序崩溃（（

我无法解决这个问题。我添加了这个运算符IF：if (etText.getText().toString().trim().length()> 0) 但它没有解决问题。

我有一点开发经验和我在YouTube上的课程中看到的代码

如果你帮助我，我将非常高兴，对不起大量的代码

    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);
    }
  }
}

Answer 1

我认为这些代码行有点令人困惑，而且你没有检查mEmail.getText()中的空指针异常，因此调用mEmail.getText().toString()可能会导致NullPointerException被抛出，使您的应用程序崩溃（如果您发送空文本）。

 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();

应该是：

 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
}

Answer 2

可能未正确设置字段：

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

检查调试器，这两个变量都不为空。如果它们为null，则布局文件activity_driver_login.xml中可能存在问题。也许没有email或password的编辑文本。

Answer 3

错误是在您使用;时的第二个if条件中，条件应该相反。检查此代码

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);
    }
}

使用空编辑文字

3 个答案: