java面试题

public class Demo1 {{System.out.println(1);}static{System.out.println(2);}public Demo1(){System.out.println(3);}}

Demo1运行结果：由于程序没有main方法，所以会报错

public class Demo2 extends Demo1{{System.out.println("A");}static{System.out.println("B");}public Demo2(){System.out.println("C");}public static void main(String[] args) {Demo1 demo1 = new Demo2();Demo2 demo2 = new Demo2();}}

运行结果：

2

B

1

3

A

C

1

3

A

C