StringBuilder 删除最后一条记录末尾的逗号

Question

我正在使用 StringBuilder 在记录之间显示逗号，但也在最后一条记录的末尾添加逗号

如何控制这个？我不喜欢在最后一条记录的末尾看到逗号 - 因为它没用

   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

为最后一项添加检查。

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

或：

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

Answer 2

或者循环直到 size - 1，然后在 wards 后面添加最后一个元素，不带逗号。

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 3

    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 4

Java 8 解

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

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）使它更干净：

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

Answer 5

你可以把它写在前面，而不是放在最后：-

        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 6

您可以只删除最后一个字符：

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

这将是最简单的解决方案。

Answer 7

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

StringBuilder 删除最后一条记录末尾的逗号

StringBuilder remove comma at the end of Last record

java

stringbuilder

Java 8 解