#java8学习- StringJoiner

• 摘要：StringJoiner是java8新增的一个类,主要是帮助我们把一个列表拼接字符串,看下面一个例子:StringJoinerjoiner=newStringJoiner(",","(",")");joiner.add("a").add("b").add("c");joiner.toString();//输出"(a,b,c)"有时候我们需
• StringJoiner是java8新增的一个类,主要是帮助我们把一个列表拼接字符串,看下面一个例子:

StringJoiner joiner = new StringJoiner(",","(",")");joiner.add("a").add("b").add("c");joiner.toString();//输出 "(a,b,c)"

有时候我们需要拼接这样的sql, select * from a where id in (1,2,3,4)
再下面这个例子:
List<Integer> numbers = Arrays.asList(1, 2, 3, 4);String commaSeparatedNumbers = numbers.stream() .map(i -> i.toString()) .collect(Collectors.joining(", "));System.out.println(commaSeparatedNumbers);//1, 2, 3, 4

java8对String增加了一个join方法:
List<String> list = Arrays.asList("apple","banana","orange") ;String message = String.join("-", list);//message 的值是: "apple-banana-orange"

还可以这样写:
String.join("-", "apple","banana","orange")