这是我正在尝试的代码。我想将数据添加到子节点 结果 并显示这些值的总和:
FirebaseDatabase firebaseDatabase1 = FirebaseDatabase.getInstance();
DatabaseReference databaseReference1 = firebaseDatabase1.getReference("Sumofcal").child("result");
ValueEventListener valueEventListener1 = new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot1) {
String itsme = String.valueOf(Objects.requireNonNull(dataSnapshot1.getValue()));
Log.i("child", String.valueOf(itsme));
int sum = 0;
for (DataSnapshot ds : dataSnapshot1.getChildren()) {
sum = Integer.parseInt(sum + itsme);
}
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
};
databaseReference1.addValueEventListener(valueEventListener1);
这是logcat的输出:
java.lang.NumberFormatException: For input string: "0{-LSxVZ3hsemUKAYOh0Gn= 95, -LSxVZnx5Bhv2C33_lk-= 10, -LSxVNYT0BJDytRaFXzb= 16}"
at java.lang.Integer.parseInt(Integer.java:521)
at java.lang.Integer.parseInt(Integer.java:556)
at com.example.itsandpro.Signup.Api.SearchAdapter$2.onDataChange(SearchAdapter.java:135)
at com.google.firebase.database.core.ValueEventRegistration.fireEvent(com.google.firebase:firebase-database@@16.0.5:75)
at com.google.firebase.database.core.view.DataEvent.fire(com.google.firebase:firebase-database@@16.0.5:63)
at com.google.firebase.database.core.view.EventRaiser$1.run(com.google.firebase:firebase-database@@16.0.5:55)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6119)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
我有这样的实时数据库设置。我想将pushId与数字分开,然后对所有值进行加峰处理。
Sumofcal
result
-LSxVNYT0BJDytRaFXzb:
" 16"
-LSxVZ3hsemUKAYOh0Gn:
" 95"
-LSxVZnx5Bhv2C33_lk-:
" 10"
答案 0 :(得分:0)
要解决此问题,请使用以下代码行:
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference resultRef = rootRef.child("Sumofcal").child("result");
ValueEventListener valueEventListener = new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
int total = 0;
for(DataSnapshot ds : dataSnapshot.getChildren()) {
int number = Integer.valueOf(ds.getValue(String.class).replaceAll(" ", ""));
total = total + number;
}
Log.d(TAG, "total= " + total);
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
Log.d(TAG, databaseError.getMessage()); //Don't ignore errors!
}
};
resultRef.addListenerForSingleValueEvent(valueEventListener);
您的logcat中的结果将是:
total= 121
顺便说一句,我强烈建议您在创建总和时使用数字而不使用不字符串。另外,请注意您的值中存在的空间:
" 16"
// ^