Question

我是应用开发的新手（Android Studio）。我有两个类，一个是main类，另一个是连接到firebase的类（数据库），它检查用户是否存在并分别回答true或false并打印一些语句。问题是即使任务成功并且返回false，android studio也不会等待响应。我应该进入logcat的打印语句应该是 “这里1”，“这里2”，然后“这里3”。但这给了我“这里2”，“这里3”，然后是“这里1”。

我知道它必须执行线程操作或类似操作。

public class loginpage extends AppCompatActivity {
    private Button Login;
    private EditText user_email_txt;
    private EditText user_password_txt;
    private ProgressBar wait_bar;
    private String[] user_name_password ;

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

        find_all_views();

        Login.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                getuser_login_details();
                disable_all_views();
                Activate_wait_bar();
                final Database login = new Database();
                boolean decision = login.sign_in(user_name_password[0], user_name_password[1]);
                System.out.println("here 3");
            }
        });

    }

    private void find_all_views() {
        user_email_txt =  findViewById(R.id.UserName);
        user_password_txt = findViewById(R.id.Password);
        Login = findViewById(R.id.submit_button);
        wait_bar =  findViewById(R.id.wait_bar);
    }

    private void getuser_login_details() {
        user_name_password =  new String[2];
        user_name_password[0] = user_email_txt.getText().toString();
        user_name_password[1] = user_password_txt.getText().toString();
    }

    private void disable_all_views() {
        user_email_txt.setVisibility(View.INVISIBLE);
        user_password_txt.setVisibility(View.INVISIBLE);
        Login.setVisibility(View.INVISIBLE);
    }

    private void Activate_wait_bar() {
        wait_bar.setVisibility(View.VISIBLE);
    }
}

public class Database  {
    private FirebaseAuth connect_databse;
    private boolean authorisation;
    public Database() {}

    public boolean sign_in(String user_name, String Password) {
        authorisation = false;
        connect_databse = FirebaseAuth.getInstance();
        connect_databse.signInWithEmailAndPassword(user_name, Password)
                .addOnCompleteListener(new OnCompleteListener<AuthResult>() {
                    @Override
                    public void onComplete(@NonNull Task<AuthResult> task) {
                        if (task.isSuccessful()) {
                            FirebaseUser user = connect_databse.getCurrentUser();
                            authorisation =  true;
                            System.out.println("here 1");
                        }
                    }
                });
        System.out.println("here 2");
       return authorisation;
    }
}

如果任务成功，则应按打印语句“ here 1”，“ here 2”和“ here 3”的顺序返回authorization = true。

Answer 1

创建一个新文件：

interface OnCompleteListener {
    void onComplete();
}

在数据库类中：

 public class Database {

private FirebaseAuth connect_databse;

private boolean authorisation;

public Database() {

}

public void sign_in(String user_name, String Password,final OnCompleteListener listener) {

    authorisation = false;

    connect_databse = FirebaseAuth.getInstance();

    connect_databse.signInWithEmailAndPassword(user_name, Password)
            .addOnCompleteListener(new OnCompleteListener<AuthResult>() {
                @Override
                public void onComplete(@NonNull Task<AuthResult> task) {
                    if (task.isSuccessful()) {
                        FirebaseUser user = connect_databse.getCurrentUser();
                        authorisation =  true;
                        System.out.println("here 1");
                        listener.onComplete();
                        System.out.println("here 2");
                    }
                }
            });
}

活动中：

Login.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

        getuser_login_details();

            disable_all_views();

            Activate_wait_bar();

           final Database login = new Database();

           boolean decision = login.sign_in(user_name_password[0], user_name_password[1], new OnCompleteListener{
               @Override
               public void onComplete(){
                    System.out.println("here 3");
               }
           });

        }
    });

Answer 2

使用网络连接或调用API从服务器获取数据时，必须使用后台线程，并且在完成任务后，将运行OnComplete中的代码。但是主线程不会停止执行您的任务，而是依次从OnComplete方法中运行所有代码。

在这种情况下，您可以使用CallBackMethod。

活动没有停止响应

2 个答案: