java中INTEGER的取值范围详解

public static void main(String[] args) 
	{
		Integer a = new Integer(1);//此处若使用new，则a,b比较==值必为false
		int c = 1;
		Integer b = 1;
 
		System.out.println(a == c); // true
		System.out.println(a == b); // false
		
		Integer f1 = 100, f2 = 100, f3 = 150, f4 = 150;
		
		System.out.println(f1 == f2); // true
		System.out.println(f3 == f4); // false

public class AutoboxingTest {
 
    public static void main(String args[]) {
 
        // Example 1: == comparison pure primitive – no autoboxing
        int i1 = 1;
        int i2 = 1;
        System.out.println("i1==i2 : " + (i1 == i2)); // true
 
        // Example 2: equality operator mixing object and primitive
        Integer num1 = 1; // autoboxing
        int num2 = 1;
        System.out.println("num1 == num2 : " + (num1 == num2)); // true
 
        // Example 3: special case - arises due to autoboxing in Java
        Integer obj1 = 1; // autoboxing will call Integer.valueOf()
        Integer obj2 = 1; // same call to Integer.valueOf() will return same
                            // cached Object
 
        System.out.println("obj1 == obj2 : " + (obj1 == obj2)); // true
 
        // Example 4: equality operator - pure object comparison
        Integer one = new Integer(1); // no autoboxing
        Integer anotherOne = new Integer(1);
        System.out.println("one == anotherOne : " + (one == anotherOne)); // false
 
    }
 
}
 
Output:
i1==i2 : true
num1 == num2 : true
obj1 == obj2 : true
one == anotherOne : false

public static void main(String []args) {
    Integer a = 100;
    Integer b = a;//此时b指针指向值为100的堆地址  即a的堆地址，a==b成立
    a++;//此时a指向的值发生变化为101，a指针指向101的堆地址。而b任然指向100
    System.out.println(a==b);
}

         Integer b1 = 12;

     Integer b2 = 12;