java学习进展到类,首先就对万类之父Object类进行举例练习,这里我是对一维数组和接口用Object接受数组和接口。
package test1; public class enum1 { public static void main(String[] args) { int temp[] = {1,3,5,7,9}; //测试于Object类接收数组 Object obj = temp; print(obj); A test = new B();//向上转型,实例化 System.out.println(test.getinfo()); System.out.println(" "); Object obj2 = test; //向上转型 /*System.out.println(obj2.getinfo);此行代码无法运行,因为向上转型,子类方法无法运行*/ A x = (A)obj2; //向下转型 System.out.println(x.getinfo()); } public static void print(Object o) { if(o instanceof int[]) { int x[] = (int[])o; for(int i =0;i<x.length;i++) { System.out.println(x[i]+" "); } } }} interface A { public String getinfo(); } class B implements A { public String getinfo() { return "hello world!"; } }