2024/Java密封类

• 定义密封类 SealedParent ， 子类A、B、C，同时继承List接口

import java.util.List;

public sealed interface SealedParent extends List permits A, B, C {
    
    void test();
}

密封类子类

public final class A implements SealedParent {
    
}
~~~




#  Java模式匹配


~~~
    public static void main(String[] args) {
        Object a = 1;
        switch (a){
            //如果是Integer 匹配Integer
            case Integer i-> System.out.println(i);
            case String s->{
                //字符串匹配
                System.out.println("多行");
                System.out.println("多行");
            }
            //支持null
            case null-> System.out.println("null");
            //默认
            default -> System.out.println("default");
        }
    }

~~~


~~~
        int a = 3;
        switch (a){
            case 1-> System.out.println(1);
            case 2->{
                System.out.println("多行");
                System.out.println("多行");
            }
            default -> System.out.println("default");
        }

~~~