int num = 4568;
int shiwei=0,baiwei=0,qianwei=0,gewei=0;
qianwei = num / 1000;
baiwei = (num % 1000) / 100;
shiwei = (num / 10 ) % 10;
gewei = (num %100) % 10;
System.out.println(qianwei + ":" + baiwei + ":" + shiwei + ":" + gewei);