Differences between comparing primitive int and Integer object

Code overview of a method illustrating how value comparisons and reference comparisons differ for the primitive type int and its object wrapper Integer, as well as demonstrating the Integer object caching mechanism.

private static void intPool() {
    int x = 127;
    int y = 127;
    System.out.println(x == y);

    x = 300;
    y = 300;
    System.out.println(x == y);

    Integer obj1 = 127;
    Integer obj2 = 127;
    System.out.println(obj1 == obj2);

    obj1 = 300;
    obj2 = 300;
    System.out.println(obj1 == obj2);
}