在 Java 示例中使用“For 循环”

Question

我正在用 Java 做一个练习。这是在for Loop 上使用的。下面的代码显示了while 循环。这是“啤酒之歌”的例子。

int beerNum = 99;
String word = "bottles";
while (beerNum > 0) {
   if (beerNum == 1) {
       word = "bottle";
   }
   System.out.println(beerNum + " " + word + " of beer on the wall");
   System.out.println(beerNum + " " + word + " of beer");
   System.out.println("Take one down.");
   System.out.println("Pass it around.");
   beerNum = beerNum -1;
   if (beerNum > 0) {
      System.out.println(beerNum + " " + word + " of beer on the wall");
   }
   else {
      System.out.println("No more bottles of beer on the wall");
   }
} // end loop

输出是：

OUTPUT:
-------------
99 bottles of beer on the wall
99 bottles of beer
Take one down.
Pass it around.
98 bottles of beer on the wall
98 bottles of beer on the wall
98 bottles of beer
Take one down.
Pass it around.
97 bottles of beer on the wall
97 bottles of beer on the wall
97 bottles of beer
Take one down.
Pass it around.
----------
----------
---------
---------

2 bottles of beer on the wall
2 bottles of beer on the wall
2 bottles of beer
Take one down.
Pass it around.
1 bottles of beer on the wall
1 bottle of beer on the wall
1 bottle of beer
Take one down.
Pass it around.
No more bottles of beer on the wall

上面的输出显示，当歌曲以 1 瓶啤酒结束时，它会说“墙上不再有瓶啤酒”。

现在我的任务是使用这个“啤酒歌曲”示例，并使用 for 循环而不是 while 循环来重写它。

我这样做了，但输出看起来与 while 循环的输出不匹配。 这是使用for循环的代码和输出。

 String word = "bottles";
 for(int beerNum = 99; beerNum > 0; beerNum --) {
     if(beerNum==1) {
         word = "bottle";
     }
     System.out.println(beerNum + " " + word + " of beer on the wall");
     System.out.println(beerNum + " " + word + " of beer");
     System.out.println("Take one down.");
     System.out.println("Pass it around.");
     beerNum = beerNum -1;
     if (beerNum > 0) {
        System.out.println(beerNum + " " + word + " of beer on the wall");
     }
     else {
        System.out.println("No more bottles of beer on the wall");
     }

--------------------------------------------------------------------------
Output

99 bottles of beer on the wall
99 bottles of beer
Take one down.
Pass it around.
98 bottles of beer on the wall
97 bottles of beer on the wall (should be 98)
97 bottles of beer   (should be 98)
Take one down.
Pass it around.
96 bottles of beer on the wall 
95 bottles of beer on the wall (should be 96)
95 bottles of beer (should be 96)
Take one down.
Pass it around.
94 bottles of beer on the wall 
93 bottles of beer on the wall (should be 94)
93 bottles of beer (should be 94)
Take one down.
Pass it around.
--------------
--------------
--------------
    4 bottles of beer on the wall
3 bottles of beer on the wall (should be 4)
3 bottles of beer (should be 4)
Take one down.
Pass it around.
2 bottles of beer on the wall
1 bottle of beer on the wall (should be 2)
1 bottle of beer  (should be 2)
Take one down.
Pass it around.
No more bottles of beer on the wall

使用for 循环时输出显示不正确。谁能帮我解决这个问题？

Answer 1

问题是在for 循环中变量已经被递减。 （for(int beerNum = 99; beerNum > 0; beerNum --)强调beerNum--部分）

因此，beerNum = beerNum -1; 语句将递减两次。您需要删除此行。

String word = "bottles";
for(int beerNum = 99; beerNum > 0; beerNum --) {
     if(beerNum==1) {
         word = "bottle";
    }
    System.out.println(beerNum + " " + word + " of beer on the wall");
    System.out.println(beerNum + " " + word + " of beer");
    System.out.println("Take one down.");
    System.out.println("Pass it around.");
    if (beerNum > 1) {
       System.out.println(beerNum -1 + " " + word + " of beer on the wall");
    } else {
       System.out.println("No more bottles of beer on the wall");
    }
}

Answer 2

您正在减少 for 循环代码中的 beerNum 变量 两次。首先是循环头，然后是循环体。

这就是全部。