Java 从用于FirebaseAuth的onCompleteListener启动一个片段？

我试图从另一个片段中打开一个片段，但出现错误

该应用程序在主屏幕上打开，显示底部导航视图。单击其中一个选项卡将打开一个片段，其中包含Firebase用户的登录屏幕。在输入详细信息并按下登录按钮后，它应该验证用户并打开另一个片段

在按login之前，一切正常

下面是一个工作示例，其中两个片段实际上都是活动，并且一切正常

import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.v7.app.AppCompatActivity;
import android.text.TextUtils;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.auth.AuthResult;
import com.google.firebase.auth.FirebaseAuth;

public class LoginActivity extends AppCompatActivity implements View.OnClickListener{

public Button btnLogIn;
private EditText inputEmail, inputPassword;
private FirebaseAuth mAuth;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    mAuth = FirebaseAuth.getInstance();

    if (mAuth.getCurrentUser() != null) {
        startActivity(new Intent(LoginActivity.this, SecondPage.class));
        finish();
    }

    setContentView(R.layout.activity_login);

    btnLogIn = findViewById(R.id.btn_login);
    inputEmail = findViewById(R.id.email);
    inputPassword = findViewById(R.id.password);

    findViewById(R.id.btn_login).setOnClickListener(this);

    mAuth = FirebaseAuth.getInstance();
}

@Override
public void onClick(View view){
    final String email = inputEmail.getText().toString();
    final String password = inputPassword.getText().toString();

    if (TextUtils.isEmpty(email)) {
        Toast.makeText(getApplicationContext(), "Enter email address!", Toast.LENGTH_SHORT).show();
        return;
    }

    if (TextUtils.isEmpty(password)) {
        Toast.makeText(getApplicationContext(), "Enter password!", Toast.LENGTH_SHORT).show();
        return;
    }

    mAuth.signInWithEmailAndPassword(email, password)
            .addOnCompleteListener(this, new OnCompleteListener<AuthResult>(){
                @Override
                public void onComplete(@NonNull Task<AuthResult> task) {
                    if (!task.isSuccessful()) {
                        if (password.length() < 6) {
                            inputPassword.setError(getString(R.string.minimum_password));
                        } else {
                            Toast.makeText(LoginActivity.this, getString(R.string.auth_failed), Toast.LENGTH_LONG).show();
                        }
                    } else {
                        Intent intent = new Intent(LoginActivity.this, SecondPage.class);
                        startActivity(intent);
                        finish();
                    }
                }
            });
}

}

我知道finish（）方法不能在片段中调用，但我在网上尝试过其他解决方案，但没有一个有效。这是我能得到的最接近的了

---

谢谢

您希望父活动打开片段

您可以通过接口和回调来实现这一点

在未完成的情况下，使用方法启动对活动的回调，以启动第二个片段

---

阅读此文了解更多信息：

Firebase只会给您的主要问题增加噪音。花点时间学习活动和片段是如何工作的！官方文档非常酷。对于回调和接口方法，这些方法的参数是什么。感谢您的快速响应。我会很快查出来的谢谢你的好消息。但是，在我的上下文中，参数是什么？

package com.nikelspot.app;

import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.app.Fragment;
import android.text.TextUtils;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.auth.AuthResult;
import com.google.firebase.auth.FirebaseAuth;

public class LoginActivity extends Fragment implements View.OnClickListener {

    public LoginActivity() {
        //needed empty constructor
    }

    public Button btnLogIn;
    private EditText inputEmail, inputPassword;
    private FirebaseAuth mAuth;

    @Override
    public View onCreateView(LayoutInflater inflater,
                             ViewGroup container,
                             Bundle savedInstanceState) {

        mAuth = FirebaseAuth.getInstance();

        if (mAuth.getCurrentUser() != null) {
            startActivity(new Intent(getActivity(), SecondPage.class));
        }

        View rootView = inflater.inflate(R.layout.frag_login,
                container, false);

        btnLogIn = rootView.findViewById(R.id.btn_login);
        inputEmail = rootView.findViewById(R.id.email);
        inputPassword = rootView.findViewById(R.id.password);
        mAuth = FirebaseAuth.getInstance();

        rootView.findViewById(R.id.btn_login).setOnClickListener(this);
        mAuth = FirebaseAuth.getInstance();
        return rootView;
    }

    @Override
    public void onClick(View view){
        final String email = inputEmail.getText().toString();
        final String password = inputPassword.getText().toString();

        if (TextUtils.isEmpty(email)) {
            Toast.makeText(getActivity(), "Enter email address!", Toast.LENGTH_SHORT).show();
            return;
        }

        if (TextUtils.isEmpty(password)) {
            Toast.makeText(getActivity(), "Enter password!", Toast.LENGTH_SHORT).show();
            return;
        }

        mAuth.signInWithEmailAndPassword(email, password)
                .addOnCompleteListener(this, new OnCompleteListener<AuthResult>(){
                    @Override
                    public void onComplete(@NonNull Task<AuthResult> task) {
                        // If sign in fails, display a message to the user. If sign in succeeds
                        // the auth state listener will be notified and logic to handle the
                        // signed in user can be handled in the listener.

                        if (!task.isSuccessful()) {
                            // there was an error
                            if (password.length() < 6) {
                                inputPassword.setError(getString(R.string.minimum_password));
                            }
                            else {
                                Toast.makeText(getActivity(), getString(R.string.auth_failed), Toast.LENGTH_LONG).show();
                            }
                        }

                        else {
                            Intent intent = new Intent(getActivity(), SecondPage.class);
                            startActivity(intent);
                            finish();
                        }
                    }
        });
    }

}

  else {
          Intent intent = new Intent(getActivity(), SecondPage.class);
          startActivity(intent);
          finish();
        }