Integer auto-packing unpacking bug, creating objects in 128 to 127

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public class Demo3 {public static void main (string[] args) {Integer a = 1;integer b = 2;integer c = 128;integer D = 128;in Teger E = 321;integer f = 321; Long g = 3L; System.out.println (System.identityhashcode (c));//366712642system.out.println (System.identityhashcode (d));// 1829164700//actually, when we use an integer a = number, to assign a value, the class is called the public static integer//valueOf (int i) method. public static Integer valueOf (int i) {//if (I >= -128 && i <= integercache.high)//Return integercache.ca Che[i + 128];//else//return new Integer (i);//}//Let's take a look at the code of valueof (int//i) and find out that he made an if judgment on the incoming parameter I. In the case of -128<=i<=127, the int primitive data type is used directly, but beyond this range is a new object. we//know that the "= =" symbol is a comparative memory address when comparing objects, whereas for raw data types it is a direct alignment data value. Then the problem is solved. As for why the value of the int type will be in the -128<=i<=127 range? We know that the eight-bit binary representation is exactly the range of 128 to 127. It's probably because of it. System.out.println (c = = d);//falseSystem.out.println (E = = f);//falseSystem.out.println (c = = (A + b));//Falsesystem.out . println (C.equals (A + b));//falseSystem.out.println (g = = (A + b));//TrueSystem.out.println (G.eqUals (A + b));//False type}} 

　　

Integer auto-packing unpacking bug, creating objects in 128 to 127