java - 编译期间 Int 初始化错误

Question

我是一名学生，正在研究一个使用抽象数据类型“ArrayIntLog”的简单程序 (TestLuck)。它应该生成用户确定数量的日志，并使用“compare()”方法检查在找到匹配项之前循环了多少日志条目。我收到此错误:

TestLuck.java:27: error: variable totalRuns might not have been initialized totalRuns += currentRun; ^

我怎么初始化这些变量错了？这是否与我在 for 循环中使用它们有关？

public class TestLuck{
   public static void main (String [] args){

      Random rand = new Random();
      int n = rand.nextInt(100); // gives a random integer between 0 and 99.
      Scanner kbd = new Scanner(System.in);
      double average = 0;
      int totalRuns, currentRun, upperLimit = 0;

      System.out.println("Enter the upper limit of the random integer range: ");
      ArrayIntLog arr = new ArrayIntLog(kbd.nextInt());
      System.out.println("Enter the number of times to run the test: ");
      int numTests = kbd.nextInt();

      for(int j=0; j<=numTests; j++){
         for(int i=0; i<arr.getLength(); i++){  //loops through ArrayIntLog and loads random values
            n = rand.nextInt(100);
            arr.insert(n);  //insert a new random value into ArrayIntLog
            if(arr.contains(n)){
               currentRun = i+1;
               i = arr.getLength();
            }
         }    
         totalRuns += currentRun; 
         currentRun = 0;          
      } 
   }
}

Answer 1

在Java中，局部变量总是需要在使用前进行初始化。在这里，您没有初始化 totalRuns(此处仅初始化了 upperLimit)。

int totalRuns, currentRun, upperLimit = 0;

给它(和 currentRun)一个明确的值。

int totalRuns = 0, currentRun = 0, upperLimit = 0;

此行为由 JLS 的第 4.12.5 节指定:

A local variable (§14.4, §14.14) must be explicitly given a value before it is used, by either initialization (§14.4) or assignment (§15.26)...