我试图查询Firebase数据库,但保持null返回。这里是数据库的样子:Android Firebase数据库查询返回null
与阀杆对象:
public class Stem {
private String stem;
public Stem(){}
public Stem(String stem){
this.stem = stem;
}
public String getText(){
return stem;
}
public void setText(String stem){
this.stem = stem;
}
}
而且在OnCreate
mFirebaseDatabase = FirebaseDatabase.getInstance();
mStemDatabaseReference = mFirebaseDatabase.getReference().child("Stems");
getStemButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if (mChildEventListener == null) {
mChildEventListener = new ChildEventListener() {
@Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
Stem stem = dataSnapshot.getValue(Stem.class);
mStemAdapter.add(stem);
}
@Override
public void onChildChanged(DataSnapshot dataSnapshot, String s) {
}
@Override
public void onChildRemoved(DataSnapshot dataSnapshot) {
}
@Override
public void onChildMoved(DataSnapshot dataSnapshot, String s) {
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
};
mStemDatabaseReference.addChildEventListener(mChildEventListener);
}
}
});
查询在MainActivity似乎访问数据库罚款因为它返回了Stems json数组,但是当它试图将stem添加到适配器时,它将返回为空的stem。有任何想法吗?
在点击这里没用任何 – uguboz
方式仍然没有返回干对象 – robbiestells
也许stemadapter不通知的变化。使用system.out.print打印干对象以确保它不为null – uguboz