從內部類引用的局部變量必須是最終的或有效的最終

Question

此程序是我的類的最終作業，我有問題找出爲什麼我收到錯誤「從內部類引用的局部變量必須是最終或有效的最終「。該程序正在運行併發線程來對＃的數組進行排序，然後查找該數組的高位和低位值。當我沒有併發地創建它時，我沒有這個錯誤。我正在努力確定高低變量的最終定位。

public void HiLo(int[] numbers){ 

    int high = numbers[0]; 
    int low = numbers[0]; 

    Runnable r2 = new Runnable(){ 
     @Override 
     public void run() { 
      System.out.println("The highest value is: "); 
      for (int index = 1; index < numbers.length; index++){ 
       if (numbers[index] > high) 
        high = numbers[index]; 
       System.out.println(high); 
       } 
      System.out.println(); 
      System.out.println("The lowest value is: "); 
      for (int ind = 1; ind < numbers.length; ind++){ 
       if (numbers[ind] < low) 
        low = numbers[ind]; 
       System.out.println(low); 
      } 
     } 
    }; 
    pool.execute(r2); 
} 

這是產生錯誤的代碼塊。如果我使int high =數字[0];或int low = numbers [0];最後，我得到一個錯誤，我不能使這個值最終和相反變量的錯誤消失。

下面是該程序的其餘部分。任何幫助表示讚賞。

package concurrentthread; 

import java.util.Arrays; 
import java.util.Scanner; 
import java.util.concurrent.Executor; 
import java.util.concurrent.Executors; 


public class ConcurrentThread { 

    static Executor pool = Executors.newFixedThreadPool(2); 

public static void main(String[] args) { 
    int size; 

    Scanner keyboard = new Scanner(System.in); 

    ConcurrentThread sort = new ConcurrentThread(); 
    ConcurrentThread hilo = new ConcurrentThread(); 

    System.out.println("This program will calculate the highest and lowest " 
       + "numbers entered by the user \nand also sort them in " 
       + "ascending order"); 
    System.out.println(); 
    System.out.print("How many numbers would you like in the array? "); 
     size = keyboard.nextInt(); 

    final int[] numbers = new int[size]; 

    for (int index = 0; index < numbers.length; index++){ 
     System.out.print("Please enter a number between 1 and 100: "); 
     numbers[index] = keyboard.nextInt(); 
    } 

    System.out.println(); 
    sort.Sort(numbers); 
    hilo.HiLo(numbers); 

    //System.exit(0); 
} 

public void Sort(int[] numbers){ 
    int sort = numbers[0]; 

    Runnable r1 =() -> { 
     Arrays.sort(numbers); 
     System.out.println("The sorted values are: "); 
     for (int index = 0; index < numbers.length; index++) 
      System.out.print(numbers[index] + " "); 

     System.out.println(); 
    }; 
    pool.execute(r1); 
} 

public void HiLo(int[] numbers){ 

    final int high = numbers[0]; 
    int low = numbers[0]; 

    Runnable r2 = new Runnable(){ 
     @Override 
     public void run() { 
      System.out.println("The highest value is: "); 
      for (int index = 1; index < numbers.length; index++){ 
       if (numbers[index] > high) 
        high = numbers[index]; 
       System.out.println(high); 
       } 
      System.out.println(); 
      System.out.println("The lowest value is: "); 
      for (int ind = 1; ind < numbers.length; ind++){ 
       if (numbers[ind] < low) 
        low = numbers[ind]; 
       System.out.println(low); 
      } 
     } 
    }; 
    pool.execute(r2); 
} 

}

Answer 1

你不斷更新都high和low的run()方法中，通過定義，不能有效地最終使他們。

因爲無論如何您都不需要它們在run()方法之外，只需將其中的兩條線移動即可。

public void HiLo(int[] numbers){ 

    Runnable r2 = new Runnable(){ 
     @Override 
     public void run() { 
      int high = numbers[0]; 
      int low = numbers[0]; 
      System.out.println("The highest value is: ");