如何在android firebase中找到列表的大小?
我正在开发一个应用程序,该应用程序的活动具有动态的浏览量。我遇到的问题是,我不知道如何获得Firebase中数组的大小 以下是我的代码供参考:如何在android firebase中找到列表的大小?,android,firebase,firebase-realtime-database,Android,Firebase,Firebase Realtime Database,我正在开发一个应用程序,该应用程序的活动具有动态的浏览量。我遇到的问题是,我不知道如何获得Firebase中数组的大小 以下是我的代码供参考: @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_confirm_order); parentLinearLayout =
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_confirm_order);
parentLinearLayout = (LinearLayout) findViewById(R.id.parent_linear_layout);
final FirebaseAuth mAuth = FirebaseAuth.getInstance();
final DatabaseReference mCartReference = FirebaseDatabase.getInstance().getReference().child(mAuth.getCurrentUser().getUid().toString()).child("cart");
SharedPreferences mPrefs = getSharedPreferences("label", 0);
mString = mPrefs.getString("tabletIdNum", "default_value_if_variable_not_found");
appContext = getApplicationContext();
// generate items from sortedCart into Views
// for(int i = 0; i < mCartReference.child((mString)).child("sortedCart").size(); i++){
// generate number of views here
// }
Button confirmButton = findViewById(R.id.confirmOrderButton);
confirmButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
ArrayList<String> items = new ArrayList<>();
final int childCount = parentLinearLayout.getChildCount();
for(int i = 0; i < childCount; i++){
System.out.println(parentLinearLayout.getChildAt(i));
if(parentLinearLayout.getChildAt(i).getClass() == LinearLayout.class){
for (int j = 0; j < ((LinearLayout)parentLinearLayout.getChildAt(i)).getChildCount(); j++) {
System.out.println(((LinearLayout) parentLinearLayout.getChildAt(i)).getChildAt(j));
if(((LinearLayout) parentLinearLayout.getChildAt(i)).getChildAt(j).getClass() == CardView.class){
EditText et = (EditText)((RelativeLayout)((CardView)((LinearLayout) parentLinearLayout.getChildAt(i)).getChildAt(j)).getChildAt(0)).getChildAt(1);
items.add(et.getText().toString());
System.out.println(et.getText().toString());
}
}
}
}
mCartReference.child(mString).child("itemCart").setValue(items);
mCartReference.child(mString).child("name").setValue(mString);
mCartReference.child(mString).child("translated").setValue(0);
Intent startIntent = new Intent(ConfirmOrderActivity.this, ConfirmOrderActivity.class);
startActivity(startIntent);
}
});
}
@覆盖
创建时的公共void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity\u confirm\u order);
parentLinearLayout=(LinearLayout)findViewById(R.id.parent\u linear\u layout);
final FirebaseAuth mAuth=FirebaseAuth.getInstance();
final DatabaseReference mCartReference=FirebaseDatabase.getInstance().getReference().child(mAuth.getCurrentUser().getUid().toString()).child(“购物车”);
SharedReferences mPrefs=getSharedReferences(“标签”,0);
mString=mPrefs.getString(“tabletIdNum”,“如果找不到变量,则默认值”);
appContext=getApplicationContext();
//将项目从sortedCart生成到视图中
//对于(inti=0;i
在注释掉的代码段中,我试图生成与.child(“sortedCart”)
我找不到数据库子级的
.length
或.size()
,请告诉我您是否有任何解决方案来获取数组的大小(子节点数)使用值侦听器
FirebaseDatabase database = FirebaseDatabase.getInstance();
DatabaseReference dbRef= database.getReference();
dbRef.addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot snap: dataSnapshot.getChildren()) {
Log.e(snap.getKey(),snap.getChildrenCount() + ""); // here it'll get the size
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
}});
使用价值监听器
FirebaseDatabase database = FirebaseDatabase.getInstance();
DatabaseReference dbRef= database.getReference();
dbRef.addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot snap: dataSnapshot.getChildren()) {
Log.e(snap.getKey(),snap.getChildrenCount() + ""); // here it'll get the size
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
}});
不知道为什么,但是
.getChildrenCount()
不起作用,所以我只做了公共int-sortedCartCount代码>并在for循环中递增:sortedCartCount++
不知道为什么,但是.getChildrenCount()
不起作用,所以我只做了公共int-sortedCartCount代码>并在for循环中递增:sortedCartCount++代码>