我的代码没有遍历我的firebase数据库

// 引入Firebase SDK
import com.google.firebase.database.*;

public class FirebaseExample {
    public static void main(String[] args) {
        // 初始化Firebase应用程序
        FirebaseApp.initializeApp();

        // 获取对Firebase数据库的引用
        FirebaseDatabase database = FirebaseDatabase.getInstance();
        DatabaseReference ref = database.getReference("your-node");

        // 创建查询
        Query query = ref.orderByChild("your-child");

        // 监听数据变化
        query.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                // 遍历结果并处理每个数据项
                for (DataSnapshot snapshot : dataSnapshot.getChildren()) {
                    String key = snapshot.getKey();
                    Object value = snapshot.getValue();
                    System.out.println("Key: " + key + ", Value: " + value);
                }
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {
                System.out.println("Error: " + databaseError.getMessage());
            }
        });
    }
}