StringBuilder删除最后一条记录末尾的逗号

Question

我使用StringBuilder在记录之间显示逗号，但在最后记录结束时也使用逗号

如何控制？我不想在最后一张唱片的末尾看到逗号 - 因为它没用了

   for (int i = 0; i < arrayList.size(); i++) {

        String name = arrayList.get(i).getName();
        int price = arrayList.get(i).getPrice();

        stringBuilder.append(strName);
        stringBuilder.append(" - "+price+",");

    }

        stringFinal = stringBuilder.toString();

Answer 1

Java 8解决方案

使用Java 8时不需要任何检查。您只需使用StringJoiner（或String.join()）。

StringJoiner joiner = new StringJoiner(",");
for (int i = 0; i < arrayList.size(); i++) {
    String name = arrayList.get(i).getName();
    int price = arrayList.get(i).getPrice();

    joiner.add(strName + " - " + price);
}
String joinedString = joiner.toString();

您可以利用Stream API（感谢@Sasha）使其更加清洁：

String joinedString = String.join(",", list.stream().map(
        e -> e.getName() + " - " + e.getPrice()).collect(Collectors.toList()));

Answer 2

添加对最后一项的检查。

if (i < arrayList.size() - 1) {
  stringBuilder.append(" - "+price+",");
} else {
  stringBuilder.append(" - "+price);
}

或：

stringBuilder.append(" - "+price);
if (i < arrayList.size() - 1) {
  stringBuilder.append(",");
}

Answer 3

int index = stringBuilder.lastIndexOf(",");
if (index != -1){
    stringBuilder.replace(index, index+1, "");
}
String stringFinal = stringBuilder.toString();

Answer 4

或循环直到大小 - 1然后在没有逗号的病房后添加最后一个元素。

int i = 0, price = 0;
String name = null;
for (i = 0; i < arrayList.size() - 1; i++) {
 name = arrayList.get(i).getName();
 price = arrayList.get(i).getPrice();

 stringBuilder.append(strName);
 stringBuilder.append(" - "+price+",");
}

name = arrayList.get(i).getName();
price = arrayList.get(i).getPrice();
stringBuilder.append(strName);
stringBuilder.append(" - "+price);
stringFinal = stringBuilder.toString();

Answer 5

    for (int i = 0; i < arrayList.size(); i++) {

    String name = arrayList.get(i).getName();
    int price = arrayList.get(i).getPrice();

    stringBuilder.append(strName);
    if(i== arrayList.size()-1)
       stringBuilder.append(" - "+price);
    else
    stringBuilder.append(" - "+price+",");

     }

    stringFinal = stringBuilder.toString();

Answer 6

不要把它放在最后，你可以在前面写出来，如： -

        String name = arrayList.get(0).getName();
        int price = arrayList.get(0).getPrice();

        stringBuilder.append(strName).append(" - "+price);
for (int i = 1; i < arrayList.size(); i++) {

        name = arrayList.get(i).getName();
        price = arrayList.get(i).getPrice();

        stringBuilder.append(","+strName).append(" - "+price);

    }

        stringFinal = stringBuilder.toString();

Answer 7

您可以删除最后一个字符：

 stringBuilder.deleteCharAt(stringBuilder.length()-1);
 stringFinal = stringBuilder.toString();

这将是最简单的解决方案。