public?class?HelloWorld?{
????public?static?void?main(String[]?args)?{???????
		int?sum?=?0;?//?保存?1-50?之間偶數(shù)的和????????
		int?num?=?2;?//?代表?1-50?之間的偶數(shù)????????
		do?{
			//實(shí)現(xiàn)累加求和????
????????????sum?=?sum?+?num;
			num?=?num?+?2;?//?每執(zhí)行一次將數(shù)值加2，以進(jìn)行下次循環(huán)條件判斷????????????
		}?while?(num<=50);?//?滿足數(shù)值在?1-50?之間時(shí)重復(fù)執(zhí)行循環(huán)???????
		System.out.println("?50以內(nèi)的偶數(shù)之和為："?+?sum?);
	}
}

你看錯(cuò)了，偶怎么沒看到