java - 如何在 Java 中的循环中重置变量？

Question

我正在为我的计算机科学 1100 类(class)编写一个猜数游戏，其中一部分是打印玩家尝试猜测目标数​​字的次数。我定义了一个变量 tries 来跟踪它；每次玩家猜测时，程序都会将其递增 1。

游戏在玩家猜对数字后重新开始，此时我想重置 tries 计数器。但是，我不知道该怎么做，因为每次猜到数字时程序都会递增 tries。我该怎么做？

import java.util.Scanner;
import java.util.Random;
public class Q2 {
   public static void main(String[] args) {
      Scanner kbd = new Scanner(System.in);
      Random r = new Random();
      System.out.println("Welcome to the Number Guessing Game");
      int x=0;//defining x for later
      int tries = 1;//defining tries for later
      while (x!=-1) { 
         int y = r.nextInt(101);//defining random number 0-100
         System.out.print("Guess a number between 0 and 100 or enter -1 to quit: ");
         x=kbd.nextInt();//redefining x
         x=kbd.nextInt();//redefining x
         for (int i=1;x!=-1&&x!=y;i=1) {//for loop
               if (x<-1||x>100) {//illegal condition
                  System.out.print("Out of bounds. Try again: ");
               }
               else if (x>y) {//input greater than random condition
                  System.out.print("The number is lower. Try again: ");
               }
               else if (y>x) {//random greater than input condition
                  System.out.print("The number is higher. Try again: ");
               }
               x = kbd.nextInt();//redefining x
               tries+=i;//defining pattern for tries
         }
         if (x==y) {//input=random condition
            System.out.println("Congratulations! You guessed the number in " + tries + " tries");
         }
      }
      if (x==-1) {//quit condition
         System.out.print("Thank you for playing the game!!");
         }
     }
}

Answer 1

a) 更改变量的范围

变量仅在它们定义的范围内可用。例如

while (something) { // all code inside the loop is in an inner scope
  int variable = 42;
  // variable is accessible here
}
// variable is not accessible here

这意味着，每次 while 循环执行一次迭代时，都会新创建变量。最好只在它们实际有意义的范围内定义变量(在本例中是在 while 循环中)。

b) 每次重新分配变量

另一种方法是在每次需要时重置变量。这将导致这样的设计:

int variable; // variable is defined outside the inner scope
while (something) {
  variable = 42;
  // some code that changes variable's value
}