java Android studio/Firebase在获取数据时遇到无限循环
我试图从firebaseDB中获取数据，但它一直在无限地运行，我不明白为什么
问题是：用户键入一封要寄钱的邮件。我从数据库中取出所有用户，并将书面电子邮件与每个用户的电子邮件进行比较。如果电子邮件与用户匹配（电子邮件是唯一的），则会在内部进行另一次db呼叫，以获得收件人的余额。用户的余额会被更新，收件人的余额也会被更新。 问题是，它不断地减去发送者的金额，并不断地无限地为接收者添加（通过单击一次）
我知道这与异步执行有关，但我对编程太陌生，不知道如何解决它
有人能帮忙吗？代码如下：
public void sendTo(){
final String receiverEmail = editTextReciever.getText().toString().trim();
String amountHolder = ediTextAmount.getText().toString().trim();
if(TextUtils.isEmpty(receiverEmail)){
Toast.makeText(getApplicationContext(), "Enter an email", Toast.LENGTH_LONG).show();
return;
}
if(TextUtils.isEmpty(amountHolder)){
Toast.makeText(getApplicationContext(), "Enter an amount to send", Toast.LENGTH_LONG).show();
return;
}
//If it has gotten this far, theres data in the editText (the editText can only contain numbers)
final int amount = Integer.parseInt(amountHolder);
//Looping through every user in the DB and checking if the typed email belong to any of the users in the DB
FirebaseDatabase.getInstance().getReference("users").addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
for (DataSnapshot snapshot : dataSnapshot.getChildren()){
User user = snapshot.getValue(User.class);
//If typed email matches a user in the db (emails are unique due to firebaseAuthentication), continue
if(user.getEmail().equals(receiverEmail)){
recipientUid = snapshot.getKey();
if(accountBalance - amount >= 0 && uid != snapshot.getKey()){
//I have to fetch our the balance of the user i'm sending money to so I can add the amount to his balance
FirebaseDatabase.getInstance().getReference("Accounts/" + accountType).child(snapshot.getKey()).child("balance").addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
int balanceOfReceiver = Integer.parseInt(dataSnapshot.getValue().toString());
int updatedBalance = balanceOfReceiver + amount;
//The senders balance is updated
accountBalance = accountBalance - amount;
FirebaseDatabase.getInstance().getReference("Accounts/" + accountType).child(uid).child("balance").setValue(accountBalance);
//And the recipients balance is updated
FirebaseDatabase.getInstance().getReference("Accounts/" + accountType).child(recipientUid).child("balance").setValue(updatedBalance);
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
} else {
Toast.makeText(getApplicationContext(), "You can't overdraw or send money to yourself", Toast.LENGTH_LONG).show();
}
}
}
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
}
# 1 楼答案
将ValueEventListener添加到users ref，当数据发生任何更改时，都会调用onDataChange。 减去金额，再次触发onDataChange，进入循环
在更改金额之前，您需要重新考虑代码结构或删除侦听器
这个
触发这个