Java坑人面試題之自動裝箱和拆箱後的引用數據類型和基本數據類型的計算

在Java1.5之後的版本中，引用類型Integer和基本數據類型int之間是能夠經過自動裝箱和拆箱進行計算的

例如: Integer in = 1; //it means  Integer in = new Integer(1);

in = in +1;// Integer type in convert to int type  via function Integer.intValue()

//in+1 =  in.intValue(1) + 1;

So, in = 2; //auto picking : pass Integer(2) = Interger in;

 

 

public static void functin2() {
Integer i = new Integer(1);
Integer j = new Integer(1);
System.out.println(i==j);//false
System.out.println(i.equals(j));//true

Integer a = 500;
Integer b = 500;
System.out.println(a==b);//false
System.out.println(a.equals(b));//true


//when the data in the scope of byte(127),JVM will not create new object
Integer aa = 50;
Integer bb = 50;
System.out.println(aa==bb);//true
System.out.println(aa.equals(bb));//true

}