我试图让这个工作，但它显示errro在fileReader语句

Question

这是主要类，它适用于第一步当我输入1或2为下一步它会给出错误说“错误读取文件

公共静态无效的主要（字串[] args）抛出IOException异常{

Scanner sc = new Scanner(System.in); 
    System.out.println("1.Fraction Calculator"); 
    System.out.println("2.Grading Scheme"); 
    System.out.println("Enter Your Choice:"); 
    int ip = sc.nextInt(); 
    String frac1, frac2; 
      // creating an object of Fraction class 
    Grading grad=new Grading(); 
    grad.readFile(); 
    grad.calculateAverage(); 
    grad.calculateTestAvg(); 
    // creating an object of Fraction class 
    Fraction frac =new Fraction(); 


    switch(ip){ 
     case 1: System.out.println("Enter two fractions:"); 
       // input of the two fractions 
       frac1 = sc.next(); frac2 = sc.next(); 
       // displaying the result table 
       System.out.println("Addition: " + frac.add(frac1, frac2) + "\nSubtraction: " + frac.sub(frac1,frac2) + "\nMultiplication: " + frac.mul(frac1,frac2) + "\nDivision: " + frac.div(frac1, frac2)); 
       break; 

     case 2: grad.printGrades(); break; 

     default : break; 
    } 
} 

Answer 1

因为你没有处理java.io.FileNotFoundException，则 可以抛出异常或使用try catch块来处理它

t hrows例外

void Grading()throws FileNotFoundException{ 
    FileReader fr = new FileReader("score.txt"); 
    BufferedReader br = new BufferedReader(fr); 
} 

的try-catch

void Grading(){ 

    FileReader fr = null; 
    try { 
     fr = new FileReader("score.txt"); 
    } catch (FileNotFoundException e) { 
     e.printStackTrace(); 
    } 
    BufferedReader br = new BufferedReader(fr); 
} 

Answer 2

你必须throws FileNotFoundException与FileReader所以你有两个选择：

void Grading() throws FileNotFoundException { 
    FileReader fr = new FileReader("score.txt"); 
    BufferedReader br = new BufferedReader(fr); 
} 

或者使用try{}catch(){}：

void Grading() { 
    FileReader fr; 
    try { 
     fr = new FileReader("score.txt"); 
    } catch (FileNotFoundException ex) { 
     //... 
    } 
    BufferedReader br = new BufferedReader(fr); 
} 

编辑

不要忘了导入这个库：

import java.io.BufferedReader; 
import java.io.FileNotFoundException; 
import java.io.FileReader;