查看String源码,会发现这是jdk1.8出现的新方法.主要是用来字符串拼接指定分隔符的.
String message = String.join("-", "Java", "is", "cool");
// message returned is: "Java-is-cool"
List<String> strings = new LinkedList<>();
strings.add("Java");
strings.add("is");
strings.add("cool");
String message = String.join(" ", strings);
//message returned is: "Java is cool"
Set<String> strings = new LinkedHashSet<>();
strings.add("Java");
strings.add("is");
strings.add("very");
strings.add("cool");
String message = String.join("-", strings);
//message returned is: "Java-is-very-cool"