package com.heima.wrapclass;
public class Demo4_JDK5 {
/**自动装箱：把基本数据类型转换为包装类类型 * 自动拆箱：把包装类类型转换为基本数据类型 * @param args */ public static void main(String[] args) { int x = 100; Integer i1 = new Integer(x); //装箱 int y = i1.intValue(); //拆箱 Integer i2 = 200; //自动装箱 int z = i2 + 200; //自动拆箱 System.out.println(z); }
dk1.8 运行结果：Exception in thread "main" java.lang.Error: Unresolved compilation problems: Type mismatch: cannot convert from int to Integer The operator + is undefined for the argument type(s) Integer, int at com.heima.wrapclass.Demo4_JDK5.main(Demo4_JDK5.java:14)