使用从ValueEventListener外部的Firebase数据库检索的值

问题描述 投票:0回答:1

我正在使用Android中的Java和Firebase开发应用程序,因为我从Firebase数据库中检索数据。这是我的代码

databaseReference.orderByChild("email").equalTo(email).addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                for (DataSnapshot dataSnapshot1 : dataSnapshot.getChildren()) {
                    AddFaculty addFaculty = dataSnapshot1.getValue(AddFaculty.class);
                    department = addFaculty.getDepartment();
                    year = addFaculty.getYear();
                }

            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {

            }
        });

模型类

public class AddFaculty {
    private String name;
    private String email;
    private String position;
    private String department;
    private String year;
    private String facultyId;

    public AddFaculty() {
    }

    public AddFaculty(String name, String email, String position, String department, String year, String facultyId) {
        this.name = name;
        this.email = email;
        this.position = position;
        this.department = department;
        this.year = year;
        this.facultyId = facultyId;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getEmail() {
        return email;
    }

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

    public String getPosition() {
        return position;
    }

    public void setPosition(String position) {
        this.position = position;
    }

    public String getDepartment() {
        return department;
    }

    public void setDepartment(String department) {
        this.department = department;
    }

    public String getYear() {
        return year;
    }

    public void setYear(String year) {
        this.year = year;
    }

    public String getFacultyId() {
        return facultyId;
    }

    public void setFacultyId(String facultyId) {
        this.facultyId = facultyId;
    }
}

这是我的问题。我想在valueEventListener之外使用'addFaculty'或部门和年份变量。我知道很多人问与此有关的问题。我尝试了许多与此问题相关的解决方案,但没有成功。因此,如果您知道如何实现这一点,那将是很大的帮助。

java android-studio firebase-realtime-database
1个回答
0
投票

创建用于访问变量的接口

interface CallbackFaculty {
    void passFaculty(AddFaculty addFaculty);
}

然后您可以使用interface参数创建函数

private void getFaculty(CallbackFaculty callbackFaculty) { 
     databaseReference.orderByChild("email").equalTo(email).addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
            for (DataSnapshot dataSnapshot1 : dataSnapshot.getChildren()) {
                AddFaculty addFaculty = dataSnapshot1.getValue(AddFaculty.class);
                department = addFaculty.getDepartment();
                year = addFaculty.getYear();
                callbackFaculty.passFaculty(addFaculty);
            }

        }

        @Override
        public void onCancelled(@NonNull DatabaseError databaseError) {

        }
    });
}

使用方法

getFaculty(new CallbackFaculty {
    @Override
    public void passFaculty(AddFaculty addFaculty) {
         // here you have the access of addFaculty
         // you can try logging addFaculty to check the value
    }
});

希望它对您有帮助

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