Integer a =1 , b= 2;
System.out.println("before:a="+a+" b="+b);
Field field = Integer.class.getDeclaredField("value");
field.setAccessible(true);
int temp = a.intValue();
System.out.println("before:temp="+temp);
field.set(a,b.intValue());
System.out.println("after:temp="+temp);
field.set(b,temp);
System.out.println("after:a="+a+" b="+b);
Integer c= Integer.valueOf(1);
Integer d= Integer.valueOf(2);
Integer e= new Integer(1);
System.out.println("before:c="+c+" d="+d +" e="+e);
题目很简单,你做对了吗?
Integer a =1 , b= 2;
System.out.println("before:a="+a+" b="+b);
Field field = Integer.class.getDeclaredField("value");
field.setAccessible(true);
int temp = a.intValue();
System.out.println("before:temp="+temp);
field.set(a,b.intValue());
System.out.println("after:temp="+temp);
//set()的参数是Object,Object,而Object是引用类型,不是基本类型!所以这里传入的int
temp=1,还需要先自动包装成Integer,即Integer.valueOf(temp)
//最后,利用反射给int value这个字段设值的时候,其实使用到的是Integer.intValue()值
field.set(b,Integer.valueOf(temp).intValue());
field.set(b,temp);
System.out.println("after:a="+a+" b="+b);
Integer c= Integer.valueOf(1);
Integer d= Integer.valueOf(2);
Integer e= new Integer(1);
System.out.println("before:c="+c+" d="+d +" e="+e);
before:a=1 b=2
before:temp=1
after:temp=1
after:a=2 b=2
before:c=2 d=2 e=1
Process finished with exit code 0