12.JAVA-基本数据类型的包装类操作

         //手动装箱
         Double obj1 = new Double("1.234");
         Double obj2 = new Double(1.234);

         System.out.println(obj1.equals(obj2));    //打印true
         System.out.println(obj1==obj2);           //打印false,因为obj1和obj2的地址不同
         System.out.println(obj1*2);               //直接进行数学计算, 打印2.468

         //自动装箱
         Double obj3 = 12.3;                         //等价于Double obj2 = new Double(12.3);

         //自动拆箱
         double d = obj3;                      //d = 12.3

         //手动拆箱
         d = obj3.doubleValue() ;         //d = 12.3

public class Test
{
         public static void print(Object obj)  //打印所有包装类的信息
         {
                  System.out.println(obj.toString());
         }

         public static void main(String args[]){
                  Boolean obj1 = true;
                  Integer obj2 = 10;
                  Double  obj3 = 1.234;
　　　　　　　　　　　
                  print(obj1);
                  print(obj2);
                  print(obj3);
         }
}