我有2个数组... 1个，分别是支付商品的人的名字，另一个是每个支付价格的商品。如果某人什么都没买，则在“名称”位置具有与nameArray相同索引的arrayPrice为空。如果条目为空，如何将默认值设置为“ 0”->大十进制？ 那是我的代码，即使我有1个人付款1次，也只能用[0]填充数组：
db.collection("users").document(email).collection("Group").document(groupName)
.get()
.addOnCompleteListener(new OnCompleteListener<DocumentSnapshot>() {
@Override
public void onComplete(@NonNull Task<DocumentSnapshot> task) {
if (task.isSuccessful()) {
DocumentSnapshot document = task.getResult();
// Getting all the partecipants of a group
String[] values = (String.valueOf(document.get("partecipant")).replace("[", "").replace("]", "").replace(" ", "").split(","));
for(String value : values){
nameArray.add(value);
}
Log.v("nameArraydownloaded", nameArray.toString());
}
}
});
DocumentReference docRef = db.collection("users").document(email).collection("Group").document(groupName);
docRef.collection("Payments")
.get()
.addOnSuccessListener(new OnSuccessListener<QuerySnapshot>() {
@Override
public void onSuccess(QuerySnapshot queryDocumentSnapshots) {
for (QueryDocumentSnapshot document : queryDocumentSnapshots) {
//Extracting payment description from each document
cont += 1;
//Extracting cost and who payed from each document
price = document.getString("cost");
priceFloat += Float.parseFloat(price);
priceArray.add(new BigDecimal(price));
name = document.getString("paid by");
nameArray.add(name);
}
numberOfPaymentTV.setText(String.valueOf(cont));
totalCost.setText(decimalFormat.format(priceFloat) + "€");
cpp = decimalFormat.format(priceFloat / Float.parseFloat(num_partecipants));
costPerPerson.setText(cpp + "€");
while(priceArray.size() < nameArray.size()){
priceArray.add(BigDecimal.valueOf(0));
}
if (nameArray.size() > 0) {
// Manipulate the arrays
Map<String, BigDecimal> totals = new HashMap<>();
for (int i = 0; i < nameArray.size(); ++i) {
String name = nameArray.get(i);
BigDecimal price = priceArray.get(i);
BigDecimal total = totals.get(name);
if (total != null) {
totals.put(name, total.add(price));
} else {
totals.put(name, price);
}
}
nameArray.clear();
priceArray.clear();
// Adding single name and price value for each partecipant
for (Map.Entry<String, BigDecimal> entry : totals.entrySet()) {
nameArray.add(entry.getKey());
priceArray.add(entry.getValue());
}
// Order the array by descending price
for (int i = 0; i < priceArray.size(); i++) {
for (int j = 0; j < priceArray.size() - 1; j++) {
if (priceArray.get(j).compareTo(priceArray.get(j + 1)) < 0) {
BigDecimal tempPrice = priceArray.get(j);
String tempName = nameArray.get(j);
priceArray.set(j, priceArray.get(j + 1));
nameArray.set(j, nameArray.get(j + 1));
priceArray.set(j + 1, tempPrice);
nameArray.set(j + 1, tempName);
}
}
}
Log.v("priceArray", priceArray.toString());
for (int i = 0; i < nameArray.size() - 1; i++) {
if (BigDecimal.valueOf(Float.parseFloat(cpp.replace(",", "."))).subtract(priceArray.get(i)).compareTo(BigDecimal.ZERO) < 0) {
receiverArray.add(nameArray.get(i));
}
}
for (int i = 1; i < nameArray.size(); i++) {
if (BigDecimal.valueOf(Float.parseFloat(cpp.replace(",", "."))).subtract(priceArray.get(i)).compareTo(BigDecimal.ZERO) > 0) {
debtorArray.add(nameArray.get(i));
}
}
if (receiverArray.size() > debtorArray.size()) {
for (int i = 0; i < nameArray.size() - 1; i++) {
differenceArray.add(priceArray.get(i).subtract(BigDecimal.valueOf(Float.parseFloat(cpp.replace(",", ".")))).abs());
}
} else {
for (int i = 1; i < nameArray.size(); i++) {
differenceArray.add(priceArray.get(i).subtract(BigDecimal.valueOf(Float.parseFloat(cpp.replace(",", ".")))).abs());
}
}
if (!receiverArray.isEmpty() && !debtorArray.isEmpty()) {
while (receiverArray.size() < debtorArray.size()) {
receiverArray.add(receiverArray.get(receiverArray.size() - 1));
}
while (debtorArray.size() < receiverArray.size()) {
debtorArray.add(debtorArray.get(debtorArray.size() - 1));
}
}
Log.v("recArray", receiverArray.toString());
Log.v("debArray", debtorArray.toString());
Log.v("difArray", differenceArray.toString());
customAdapter = new ReportAdapter(getActivity(), debtorArray, receiverArray, differenceArray);
listView.setAdapter(customAdapter);
}
}
具有此代码的数组为[14.00]，但名称数组中有3个人，我需要priceArray为：[14.00，0，0] 我该怎么办？
答案 0 :(得分：0)
您需要map.getOrDefault("key", <defaultValue>)。
返回指定键所映射到的值，或者 如果此映射不包含键的映射，则为defaultValue。