Java 为什么我能'；t从Firebase实时数据库检索用户名和密码

我想使用Firebase实时数据库中存储的用户名和密码登录。但是我的代码不起作用。我包括我的数据库图片和代码。请帮帮我

这是数据库映像：

这是我的主要活动代码MainActivity.java

databaseReference=FirebaseDatabase.getInstance().getReference("Client");
    btn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Query query = databaseReference.child("Client").orderByChild("username").equalTo(editTextUsername.getText().toString().trim());
            query.addListenerForSingleValueEvent(new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {

                        for (DataSnapshot user : dataSnapshot.getChildren()) {
                            Users usersBean = user.getValue(Users.class);
                            if (usersBean.password.equals(editTextPassword.getText().toString().trim())) {
                                Toast.makeText(MainActivity.this, "success", Toast.LENGTH_SHORT).show();
                            } else {
                                Toast.makeText(MainActivity.this, "wrong", Toast.LENGTH_SHORT).show();
                            }
                        }
                }

                @Override
                public void onCancelled(DatabaseError databaseError) {

                }
            });
        }
    });

下面是我的用户java类users.java

    public class Users {
    String email;
    String id;
    String password;
    String username;

    public Users() {

    }

    public Users(String email, String id, String password, String username) {
        this.email = email;
        this.id = id;
        this.password = password;
        this.username = username;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }
}

---

要解决此问题，请更改以下代码行：

databaseReference=FirebaseDatabase.getInstance().getReference("Client");

到

无需获取

客户端

节点的引用，因为您在查询中使用了对

.child（“客户端”）

的调用

编辑：

要根据您的评论解决您现在遇到的错误，请将

Users

类中

id

属性的类型从

String

更改为

long

，并将getter和setter更改为如下所示：

public class Users {
    String email;
    long id;
    String password;
    String username;

    public Users() {

    }

    public Users(String email, long id, String password, String username) {
        this.email = email;
        this.id = id;
        this.password = password;
        this.username = username;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public long getId() {
        return id;
    }

    public void setId(long id) {
        this.id = id;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }
}

---

不工作。当我单击按钮时，应用程序停止。@Alex Mamoi如果应用程序崩溃，则会出现堆栈跟踪。请在logcat上查找，并将其添加到您的问题中。这是logcat@Alex Mamono不工作…我尝试添加indexOn仍然失败..请在IDE中实现它并运行..@Alex Mamo“不工作”没有帮助。为什么不工作？到目前为止，我们修正了两个错误，通常一次只回答一个问题。现在有什么问题？你还有其他错误吗？

public class Users {
    String email;
    long id;
    String password;
    String username;

    public Users() {

    }

    public Users(String email, long id, String password, String username) {
        this.email = email;
        this.id = id;
        this.password = password;
        this.username = username;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public long getId() {
        return id;
    }

    public void setId(long id) {
        this.id = id;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }
}