错误：MainActivity 不是抽象的，并且不会覆盖 OnClickListener 中的抽象方法 onClick(View)

Question

I need help with a problem. It's probably an easy one, but I don't know what to do!
My error:

error: MainActivity is not abstract and does not override abstract method onClick(View) in OnClickListener

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    Button btRegister;
    ImageView circle1;
    TextView tvLogin;
    Button login;
    EditText mEmail,mPassword;
    FirebaseAuth fAuth;


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

        btRegister = findViewById(R.id.btRegister);
        tvLogin = findViewById(R.id.tvLogin);
        circle1 = findViewById(R.id.circle1);
        login = findViewById(R.id.btLogin);
        mEmail = findViewById(R.id.etUsername);
        mPassword = findViewById(R.id.etPassword);

      //  if(fAuth.getCurrentUser() != null){
      //      startActivity(new Intent(getApplicationContext(),Startseite.class));
      //      finish();
      //  }

       // btRegister.setOnClickListener(this);
        login.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String email = mEmail.getText().toString().trim();
                String password = mPassword.getText().toString().trim();

                if (TextUtils.isEmpty(email)) {
                    mEmail.setError("Benutzername is Required.");
                    return;
                }

                if (TextUtils.isEmpty(password)) {
                    mPassword.setError("Password is Required.");
                    return;
                }



                // authenticate the user

                fAuth.signInWithEmailAndPassword(email, password).addOnCompleteListener(new OnCompleteListener<AuthResult>() {
                    @Override
                    public void onComplete(@NonNull Task<AuthResult> task) {
                        if (task.isSuccessful()) {
                            Toast.makeText(MainActivity.this, "Logged in Successfully", Toast.LENGTH_SHORT).show();
                            startActivity(new Intent(getApplicationContext(), MainActivity.class));
                        } else {
                            Toast.makeText(MainActivity.this, "Error ! " + task.getException().getMessage(), Toast.LENGTH_SHORT).show();

                        }

                    }
                });

            }
        });
    }



}

Answer 1

Your MainActivity class unnecessarily implements the View.OnClickListener interface. Remove the implements View.OnClickListener and it will work.

Answer 2

You Need to implement onClick method in your activity, when you implement the View.OnClickListener Interface. You can delete this implementation, as you assign the onClickListener in your Code for your loginbutton.

You can implement the View.OnClickListener for your activity, implement the onClick method inside your activity,set every onClickListener for each View to this and catch all Event in the onClick method of your Activity with a switch for the id. This is something i do, when i got some onClick Methods in one activity to have all Methods for onClick in one place