java - “While”循环未执行？

Question

我的代码中有一条注释来解释我想要的最终结果是什么，但请不要在回答这个问题时回答我如何实现该目标。

基本上，我有一个标记为“currentNum”的 int，它等于 1。我有一个 while 循环，要执行到 cu​​rrentNum 小于 400 万为止。但是，由于某种原因，循环没有执行。 while 循环之外的所有内容都会执行，但 while 循环本身不会执行。

控制台上显示一次“HI”。 控制台中不显示“LOOP”。

代码:

 /*Each new term in the Fibonacci sequence is generated by adding the previous two terms. 
  * By starting with 1 and 2, the first 10 terms will be:
  * 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...
  * By considering the terms in the Fibonacci sequence whose values do not exceed four million, 
  * find the sum of the even-valued terms.*/

public class Solution {

public static void main(String args[]) {

    int lastNum1 = 0;
    int lastNum2 = 0;
    int currentNumEven = 0;
    int currentNum = 1;
    int sumEven = 0;
    boolean last = true;

    System.out.println("HI");

    while(currentNum < 4000000);

    System.out.println("LOOP");

    currentNum = currentNum + (lastNum1 + lastNum2);

    if(last) {
        lastNum1 = currentNum;
        last = !last;
    } else {
        lastNum2 = currentNum;
        last = !last;
    }

    if(currentNum % 2 == 0) {
        currentNumEven = currentNum;
        sumEven += currentNum;
        System.out.println(currentNumEven);
        System.out.println(currentNum);
    }

    if(currentNum < 4000000) {
    currentNum++;

    } else {
        System.out.println("Sum of all even Fibonacci values: " + sumEven + "\n Last even number of sequence below 4,000,000" + currentNumEven);
      }

   }

}

Answer 1

错误在这一行:

 while(currentNum < 4000000);

最后一个;放错地方了!在 while 条件之后，您应该放置一个开始 {，然后在循环末尾放置另一个 }，以关闭该 block 。像这样:

while (currentNum < 4000000) {
    // body
}