Integer c = 3;Integer d = 3;Integer e = 321;Integer f = 321;System.out.println(c == d);    trueSystem.out.println(e == f);    false

static final Integer cache[] = new Integer[-(-128) + 127 + 1]; static {    for(int i = 0; i < cache.length; i++)    cache[i] = new Integer(i - 128);}