我怎样才能修复下面的代码？

Question

我从另一个网站复制了下面的代码，因为我认为这可以节省我一些时间。但是我遇到了 3 个问题。

@Override 说 Method 不会从它的超类中覆盖方法
Toast.makeText 上的 getActivity（无法解析方法）
getActivity on Intent（无法解析方法）

它们是红色的。希望能帮到你。

package com.mz4466.photowar;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.nfc.Tag;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;

import java.util.zip.Inflater;

public class HomeActivity extends AppCompatActivity {

    private static final String TAG = "HomeActivity";

    //firebase
    private FirebaseAuth.AuthStateListener mAuthStateListener;

    //widgets
    private Button mSignOut;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.activity_home, container, false);
        mSignOut = (Button) view.findViewById(R.id.logout_button);

        setupFirebaseListener();

        mSignOut.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Log.d(TAG, "onClick: attempting to sign out the user.");
                FirebaseAuth.getInstance().signOut();
            }
        });
        return view;
    }
    private void setupFirebaseListener(){
        Log.d(TAG, "setupFirebaseListener: setting up the auth state listener.");
        mAuthStateListener = new FirebaseAuth.AuthStateListener() {
            @Override
            public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
                FirebaseUser user = firebaseAuth.getCurrentUser();
                if(user != null){
                    Log.d(TAG, "onAuthStateChanged: signed_in: " + user.getUid());
                }else{
                    Log.d(TAG, "onAuthStateChanged: signed_out");
                    Toast.makeText(getActivity(), "Signed out", Toast.LENGTH_SHORT).show();
                    Intent intent = new Intent(getActivity(), LoginActivity.class);
                    intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
                    startActivity(intent);
                }
            }
        };
    }
    @Override
    public void onStart() {
        super.onStart();
        FirebaseAuth.getInstance().addAuthStateListener(mAuthStateListener);
    }
    @Override
    public void onStop() {
        super.onStop();
        if(mAuthStateListener != null){
            FirebaseAuth.getInstance().removeAuthStateListener(mAuthStateListener);
        }
    }
}

Answer 1

您复制的代码是片段代码而不是activity，因此您需要进行一些更改

首先将任何 getActivity() 更改为 HomeActivity.this

其次，您需要覆盖 onCreate() 而不是 onCreateView() 方法，因此更改这些行


@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.activity_home, container, false);

到

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

最后从这一行 mSignOut = (Button) view.findViewById(R.id.logout_button); 中删除 view. 并完全删除这一行 return view;

我怎样才能修复下面的代码？

How can i fix the codes below?

android

logout

nullable