Java基础示例程序

来源：互联网发布：mac cp 复制文件夹编辑：程序博客网时间：2024/05/17 02:33

继承和转型

public class Demo {public static void main(String[] args) {Test t = new Test();t.test();Fest f = new Fest();f.test();Test tf = new Fest();tf.test();Fest ft = (Fest) new Test();//errorft.test();}}class Test{void test(){System.out.println("Test:test");}}class Fest extends Test{void test(){System.out.println("Fest:test");}}

//输出如下Test:testFest:testFest:testException in thread "main" java.lang.ClassCastException: Test cannot be cast to Festat Demo.main(Demo.java:10)

执行顺序

class Parent {public Parent(){System.out.println("Parent constructor.");}{System.out.println("Parent block.");}static{System.out.println("Parent static block.");}}class Child extends Parent {public Child() {System.out.println("Child constructor.");}{System.out.println("Child block.");}static{System.out.println("Child static block.");}}public class Demo {public static void main(String[] args) {new Child();}}

//输出如下Parent static block.Child static block.Parent block.Parent constructor.Child block.Child constructor.

阅读全文

0 0