檢索嵌套的對象我想以檢索數據作爲下一張照片如何火力數據
這裏就是Ø從火力地堡文檔得到
mCoursesChild.child("Courses").addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot data : dataSnapshot.getChildren()) {
Course temp = data.getValue(Course.class);
courses.add(temp));
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
和「課程「被定義爲ArrayList
ArrayList<Course> courses = new ArrayList<>();
這裏是Cours E級
public class Course {
private String mCourseName;
List<Subject> mSubjects;
public Course(){} // Default constructor required for calls to DataSnapshot.getValue(Course.class)
public Course(String CourseName){
mCourseName = CourseName;
}
public String getcourseName(){
return mCourseName;
}
public List<Subject> getSubjects(){ return mSubjects; }
}
顯然出了點問題,那麼什麼是data.getValue(Course.class)返回的值? 還是我寫錯了數據庫?
PS:我寫的數據庫對象手動
應避免在火力堂妹嵌套結構,創建複雜時增加數據檢查火力地堡文檔https://firebase.google.com/docs/database/android/structure-data –