JAVA8 String.join 字符串拼接

List names=new ArrayList<String>();
names.add("1");
names.add("2");
names.add("3");
System.out.println(String.join("-", names));

String[] arrStr=new String[]{"a","b","c"};

System.out.println(String.join("-", arrStr));

输出：

1-2-3
a-b-c