Understanding of integer constant pool

Method 1 saves value ： use Integer Class （ Constant pool ） Buffer pool （-128-127）, Exceeding the scope , A new space will be created

        Integer x=21;
		Integer x1=21;
		System.out.println(x1==x);// Memory address comparison , return true

        Integer y=133;
        Integer y1=133;// Exceeded constant pool （-128~127） The scope of the 
        System.out.println(y1==y);// Memory address comparison , return false

    Method 2 stored value ： use Integer Class （-128-127）    

         // The created value is in the cache pool range , Then it is stored in the cache pool , More than that new New space 
        Integer x2=Integer.valueOf(12);
        Integer x3=Integer.valueOf("12");//valueOf（） It's type conversion 

        System.out.println(x2==x3 );// Memory address comparison 

Method three save value ： use Integer Construction method save value , Created a new object , So the memory addresses are different
        

        Integer x4=new Integer(13);//Integer Integer construction method 
        Integer x5=new Integer("13");// String construction method （ String can only contain numbers ）
        System.out.println(x4==x5);// Yes new Keyword creation , So the memory addresses must not be equal 

When  Integer Construction method save value , Although the stored value range is within the range of the constant pool , It will also open up new memory space , Memory address must be different