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)
????????System.out.print(sum);?//?打印初始值
		do?{
			//實(shí)現(xiàn)累加求和
????????????sum+=num;
????????????System.out.print("+"?+?num);?//打印累加的偶數(shù)值
			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.print("="?+?sum?);?//打印累加的偶數(shù)合
	}
}

每一次執(zhí)行時(shí)都把sum打印出來

num=0