從檔案中讀取成績

我無法弄清楚我的編碼有什麼問題。它需要從文件中讀取文本並打印平均值，最大值和最小值。從檔案中讀取成績

import java.util.*; 
import java.io.*; 

public class LoopAndHalf{ 
    public static void main(String[]args)throws FileNotFoundException{ 
    Scanner input = new Scanner(new File("midterm.txt")); 
    int lineNo=0; 
    int id=0; 
    int grade =0; 
    String name; 

    int min=1000; 
    int max=-1000; 
    int sum=0; 
    int count=0; 

    int[] scale = new int[6]; 

    while(input.hasNextLine()){ 
     input.nextLine(); 
     lineNo++; 

    Scanner lineScan = new Scanner(line); 
    id = lineScan.nextInt(); 
    name = lineScan.next(); 
    grade = lineScan.nextInt(); 
    count++;  
    if(grade>max){ 
     max=grade; 
    } 
    if(grade<min){ 
     min=grade; 
    }  
    if(grade>=96){ 
     scale[5]++; 
    }else if(grade>=91){ 
     scale[4]++; 
    }else if(grade>=86){ 
     scale[3]++; 
    }else if(grade>=81){ 
     scale[2]++; 
    }else if(grade>=76){ 
     scale[1]++; 
    }else{ 
     scale[0]++; 
    }  
    }//end while loop 

System.out.println("Scale array: " + Arrays.toString(scale)); 
System.out.println("Count: " + count);  
double avg= (double) sum/count; 
System.out.println("Min: " + min); 
System.out.println("Max: " + max); 
System.out.println("Avg: " + avg); 

//draw histogram 
System.out.println();  
for(int i=0; i<scale.length; i++){  
    if(i==0){ 
    System.out.println(" - 75: "); 
    }else if(i==1){ 
    System.out.println("76 - 80: "); 
    }else if(i==2){ 
    System.out.println("81 - 85: "); 
    }else if(i==3){ 
    System.out.println("86 - 90: "); 
    }else if(i==4){ 
    System.out.println("91 - 95: "); 
    }else{ 
    System.out.println("95 + : "); 
    }  
}//end for loop 

int[] counts = new int[101];  // counters of test scores 0 - 100   
    while (input.hasNextInt()) {  // read file into counts array 
     int score = input.nextInt(); 
     counts[score]++;    // if score is 87, then counts[87]++ 
    }   
    for (int i = 0; i < counts.length; i++) { // print star histogram 
     if (counts[i] > 0) { 
      System.out.print(i + ": "); 
      for (int j = 0; j < counts[i]; j++) { 
       System.out.print("*"); 
      } 
      System.out.println(); 
     } 
    } 

    }//end main 
    }//end class

是不斷給我找麻煩該生產線是

Scanner lineScan = new Scanner(line);

錯誤是告訴我，行不能被解析爲一個變量，但是這是導致我的問題的唯一的事。任何指針，將不勝感激。謝謝

來源

2014-10-28 Minnie21

的錯誤意味着正是它說。您沒有一個名爲line的變量，因此您無法將其作爲參數傳遞給Scanner的構造函數。 – Daniel 2014-10-28 20:29:50

你應該使用緩衝區閱讀器 – KRUKUSA 2014-10-28 20:30:26

這可能是你想要實現的。 Java有一個內建BufferReader.IO

BufferedReader reader = new BufferedReader(new FileReader("midterm.txt")); 
String line = null; 
while ((line = reader.readLine()) != null) { 
    // Do what you want 
}

來源

2014-10-28 20:31:29 KRUKUSA

您正在讀取一行輸入，但不是將它保存在一個變量中。更改

input.nextLine();

到

String line = input.nextLine();

來源

2014-10-28 20:32:49

從檔案中讀取成績

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