有些東西與我的java程序無法正常工作

Question

我開發了一個平均等待時間程序，用戶輸入進程，到達時間等。然後它告訴你需要多長時間，但它看起來像是有錯誤，我不知道如何解決它。有人能幫我嗎。的碼的錯誤行是：

Scanner sc = new Scanner(System.in); 

誤差在線程讀取異常「主要」 java.lang.Error的：未解決問題彙編： 重複局部變量SC

這裏是代碼 包項目3;

import java.util.Random; 
import java.util.Scanner; 

public class AveragaWaitingTime { 

    static int Min(int b[], int a[], int tbt, int r, int n,int large[]) { 

      int j = 0; 

      int min = tbt; 
       int l=0;//finding larger number of process in queue 


      for (int i = n - 1; i >= 0; i--) { 

       if (b[i] < min && b[i] > 0 && r >= a[i]) { 

        min = b[i]; 
         l++; 
        j = i; 

       } 

      } 
       if(large[0]<l) 
        large[0]=l; 

      return j; 
     } 


    static int Shortesfinishtime(int n,int p[],int at[],int bt[],int bt2[],int wt[],int tat[]) 
    { 
      int tbt = 0, large[] = {0}; 

      for (int i = 0; i < n; i++) { 

       tbt = tbt + bt[i]; 

      } 


      int time[] = new int[tbt]; 

      int k = 0; 

      int q2 = 0; 



      System.out.println("Gantt Chart"); 

      System.out.print("|"); 

      //bt[0] = bt[0] - 1; 



      for (int i = 0; i < tbt; i++) { 

       int q = Min(bt, at, tbt, i, n,large); 

       if (q != q2) { 

        System.out.print(" p[" + p[q] + "]\t|"); 

        time[k++] = i; 

        wt[q] = i; 

        tat[q] = i + bt[q]; 

       } 

       bt[q] = bt[q] - 1; 

       q2 = q; 

      } 

      time[k] = tbt; 

      System.out.println(); 

      System.out.print("0\t"); 

      for (int i = 0; i <= k; i++) { 

       System.out.print(time[i] + "\t"); 

      } 
       double awt=0;//average waiting time 

       for(int i=0;i<n;i++) 
       { 

        awt=awt+wt[i]; 
       } 
       awt=awt/n; 
       System.out.println("\n AVERAGE WAITING TIME"+awt); 

       return large[0];//returning max number of process in queue at same time 

    } 

    static int shortestsizetime(int n,int process[],int ptime[],int wtime[]) 
    { 
     int temp, total=0; 
     float avg=0; 

     for(int i=0;i<n-1;i++) 
     { 
      for(int j=i+1;j<n;j++)   {    
       if(ptime[i]>ptime[j]) 
       { 
        temp = ptime[i]; 
        ptime[i] = ptime[j]; 
        ptime[j] = temp; 
        temp = process[i]; 
        process[i] = process[j]; 
        process[j] = temp; 
       } 
      } 
     } 

     wtime[0] = 0; 
     for(int i=1;i<n;i++) 
     { 
      wtime[i] = wtime[i-1]+ptime[i-1]; 
      total = total + wtime[i]; 
     } 
     avg = (float)total/n; 
     System.out.println("P_ID P_TIME W_TIME"); 
     for(int i=0;i<n;i++) 
     { 
      System.out.println(process[i]+"\t"+ptime[i]+"\t"+wtime[i]); 
     } 
     System.out.println("Total Waiting Time: "+total); 
     System.out.println("Average Waiting Time: "+avg); 

     return n-1; 
    } 
    public static void main(String argv[]) 
    { 
     //variable declaration 
     int n=100;//number of processes 
     int p[]=new int[n]; 
     int a[]=new int[n];//to store arrival time of 100 processes 
     int b[]=new int[n];//to store service/burst/processing time of 100 processes 
     int b2[]=new int[n];//to store service/burst/processing time of 100 processes 
     int w[]=new int[n];//to store waiting time of 100 processes 
     int tat[]=new int[n];//to store turaround time of 100 processes 
     int i,j; 
     int quanta;//time slice for round robin 
     double round_robin,fcfs; 

     Scanner sc = new Scanner(System.in); 
     System.out.println("Enter the no of processes"); 

     n=sc.nextInt(); 

     System.out.println("Enter the arrival time"); 
     for(i=0;i<=n;i++); 

     { 
      a[i]= sc.nextInt(); 
     } 

     System.out.println("Enter the Burst time"); 
     for(i=0;i<=n;i++) 
     { 
      b[i]=sc.nextInt(); 
      if(b[i]<0){ b[i]=b2[i]=-1*b[i];} 

     } 
     Random r= new Random(); //to generate random number 
     //generating randomly arrival time from 0 to 100 

     for(i=0;i<n;i++) 
     { 
      p[i]=i+1; 
      a[i]=r.nextInt()%101; //randomly number between 0 to 100 inclusive 
     } 

     //randomly burst/processing times from 0 to 100] 
     for(i=0;i<n;i++); 
     { 
      b[i]=(int)r.nextInt()%101; //random number from 0 to 100 inclusive 
      b2[i]=b2[i]; 

      if(b[i]<0){ b[i]=b2[i]=-1*b[i];} 
     } 
     String ans1=""; 
     do 
     { 
      int c; 
      String ans="Y"; 
      Scanner sc = new Scanner(System.in); 
      System.out.println("Enter 1: Shortestfinish time algorithm \n 2: Shortest size algorithm "); 
      c=sc.nextInt(); 

      if(c==1) 
      { 
      System.out.println("Shortest finish time:"); 
      //calling shortest finish time algorithm 

      System.out.println("Longest number of processes in queue:"+Shortesfinishtime(n,p,a,b,b2,w,tat)); 
     } 
      else 
      { 
       System.out.println("Shortest size:"); 
       //calling shortest size algorithm 
       System.out.println("Longest number of process in queue:"+shortestsizetime(n,p,b,w)); 

      } 
      System.out.println("Do you want to continue(y/n)"); 
      ans1 = sc.next(); 
     }while(ans1.equals("y")); 


     } 
} 

謝謝

Answer 1

在main方法聲明瞭一個新的掃描儀SC的兩倍。一旦開始，並在do循環中第二次。

要在DO循環解決這個問題只需刪除此行：

Scanner sc = new Scanner(System.in); 

因爲你已經宣佈它上面

Answer 2

的錯誤信息是足夠清晰的，我相信。變量sc在同一塊代碼中的2個地方定義。一個在第157行，另一個在第198行。 我建議使用像eclipse這樣的IDE進行編碼以避免這種錯誤。

Answer 3

沒有必要申報兩次掃描儀。如果你這樣做，以不同的名稱命名。

例如：

Scanner sc = new Scanner(System.in); 

二：

Scanner keyboard = new Scanner(System.in); 

一個你需要聲明兩次的唯一原因是，如果您關閉掃描儀。關閉掃描儀將不允許再次調用它，直到您聲明新的掃描儀。

keyboard.close();