其他知识
随机字符
java
UUID.randomUUID().toString() // 3db9d630-aff6-4d57-bd70-5a36e919154d
随机数字
java
Random random = new Random();
int x1 = random.nextInt(10);
switch
不需要 break
语法
java
String s = "hello";
switch (s){
case "hello" -> System.out.println("aa");
case "world" -> System.out.println("cc");
default -> System.out.println("defautl");
}
如果只有一行,可以赋值
java
String fruit = "apple";
int opt = switch (fruit) {
case "apple" -> 1;
case "pear", "mango" -> 2;
default -> 0;
}; // 注意赋值语句要以;结束
System.out.println(opt);
如果有多行,使用 yield
java
String fruit = "apple";
int opt = switch (fruit) {
case "apple" -> {
System.out.println("aaaaa");
yield 10;
} // 这里没有符号 [!code hl]
case "pear", "mango" -> 2;
default -> 0;
};
System.out.println(opt);