执行完一个练习后，我想显示一个警告对话框，上面写着“你已经执行过了。你确定要再做一次吗？”
所以在我的 firebase 中，一旦练习已经执行，isProgramExerciseFinished 将被设置为 true。但在我的代码中，对话框似乎只有在所有内容都设置为 true 后才会显示。
public void onClick(View view) {
currentWeek = programTrackers.get(0).getWeek();
DatabaseReference databaseReference = FirebaseDatabase.getInstance().getReference("ProgramTracker")
.child(GlobalUser.getmUser().getiD())
.child(programTrackers.get(0).getProgramId());
databaseReference.addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
final int childCount = (int) dataSnapshot.getChildrenCount();
int count = 0;
for (DataSnapshot snapshot : dataSnapshot.getChildren()) {
ProgramTracker programTracker = snapshot.getValue(ProgramTracker.class);
if (programTracker.getProgramExerciseWeek() == currentWeek) {
programTrackChecker.add(programTracker);
}
count++;
}
if (count == childCount) {
boolean isFinished = false;
//last iteration
for (int i = 0; i < programTrackChecker.size(); i++) {
if (programTrackChecker.get(i).isProgramExerciseFinished()) {
isFinished = true;
} else
isFinished = false;
}
if (isFinished) {
AlertDialog.Builder builder = new AlertDialog.Builder(DayExerciseActivity.this);
builder.setMessage("You have already completed all exercises. Are you sure you want to do it again?");
builder.setPositiveButton("Yes", (dialogInterface, i) -> {
startActivity(new Intent(DayExerciseActivity.this, DoProgramActivity.class)
.putExtra("programTrackers", programTrackers)
.putExtra("exerciseNum", String.valueOf(0)));
});
builder.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
dialogInterface.dismiss();
}
});
builder.show();
} else
startActivity(new Intent(DayExerciseActivity.this, DoProgramActivity.class)
.putExtra("programTrackers", programTrackers)
.putExtra("exerciseNum", String.valueOf(0)));
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
});
}
一旦为真，将显示一个对话框，一旦为假，将不显示对话框，并自动定向到 doProgramActivity
最佳答案
我相信您只会从 firebase 返回一次数据。由于回调函数是异步调用的。因此，在它被调用时，postsRef.on(...) 已经返回，紧随其后的任何代码都将运行。引用以下问题: Firebase on() does not return anything
关于android - 如何为 firebase 中的每个 child 显示警报对话框，其中包含 true，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/56338384/