Java语言程序设计-基础篇-5.25习题-毫秒转换成时、分、秒

public class Ktestone {
public static void main(String[] args) {
long num = 555550000;
convertMillis(num);
}
public static String convertMillis(long millis){
long m = millis / 1000;  //单位为秒
long n = m / 3600;  //单位为时
long k = (m % 3600) / 60;
long j = m % 60;
String str = n+" : "+k+" : "+j;
System.out.println(str);
return str;
}

}