java中冒号运算符起什么作用呢？

冒号运算符的功能:
    1.跳转
	2.三元表达式
	3.迭代循环
	4.断言
	5.switch
	6.方法(jdk8)

1 跳出标签
label: for (int i = 0; i < x; i++) {
    for (int j = 0; j < i; j++) {
        //业务代码
    }
}  

2 三元条件
int a = (b < 4)? 7: 8; // if b < 4, set a to 7, else set a to 8

3 每个循环
String[] ss = {"hi", "there"}
for (String s: ss) {
    print(s);  
}

4 断言
int a = factorial(b);
assert a >= 0: "factorial may not be less than 0"; // throws an AssertionError with the message if the condition evaluates to false

5 switch
switch (type) {
    case WHITESPACE:
    case RETURN:
        break;
    case NUMBER:
        print("got number: " + value);
        break;
    default:
        print("syntax error");
}
6 方法参考
class User {
   public static int compareByAge(User a, User b) {
       return a.birthday.compareTo(b.birthday);
   }}
}

Arrays.sort(users, User::compareByAge);