Question

我在“private reader = new BufferedReader（new FileReader（deleteRecord））;”上找到以下消息;“：

令牌“reader”上的语法错误，此令牌后面的VariableDeclartorID

代码：

import java.io.BufferedWriter;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.PrintWriter;
import java.util.Scanner;


public class ExamGradesMethods {
    private static int examMark = 0;
    private static int menu = 0;
    private static String firstName = "";
    private static String firstNameDelete = "";
    private static String lastName = "";
    private static String lastNameDelete = "";
    private static String unit = "";
    private static String entry = "";
    private static String firstCap = "";
    private static String surCap = "";
    private static Scanner scan = new Scanner(System.in);
    private static BufferedReader reader = null;
    private FileWriter grades = new FileWriter("GradeEnter.txt",true);
    private BufferedWriter bw = new BufferedWriter(grades);
    private PrintWriter out = new PrintWriter(bw);
    private reader = new BufferedReader(new FileReader(deleteRecord));
    private static File deleteRecord = new File("GradeEnter.txt");


    public static void menuActions()
    {
        System.out.println("Menu: ");
        System.out.println("1) Enter Student Grade(s)");
        System.out.println("2) View Student Grade(s)");
        System.out.println("3) Delete Grade(s)");
        System.out.println("4) Exit");
        menu = scan.nextInt();
        switch(menu) {
        case 1:
            enterGrades();
            break;
        case 2:
            viewGrades();
            break;
        case 3:
            deleteGrades();
            break;
        case 4:
            exitProgram();
            break;
        default:
            menuActions();
        }
    }

    public static void enterGrades()
    {
        System.out.print("Please enter student first name: ");
        firstName = scan.next(); 

        while(!firstName.matches("[-a-zA-Z]*"))
        {
            System.out.print("Please enter a valid first name: ");
            firstName = scan.next(); 
        }
        firstCap = firstName.substring(0,1).toUpperCase() + firstName.substring(1);


        System.out.print("Please enter student surname: ");
        lastName = scan.next();

        while(!lastName.matches("[-a-zA-Z]*"))
        {
            System.out.print("Please enter a valid surname: ");
            lastName = scan.next();
        }
        surCap = lastName.substring(0,1).toUpperCase() + lastName.substring(1);

        System.out.print("Please select Subject Unit: "); 
        unit = scan.next(); 


        System.out.print("Please enter student mark: ");
        while (!scan.hasNextInt())
        {
            System.out.print("Please enter a valid mark: ");
            scan.next();
        }
        examMark = scan.nextInt();

        if (examMark < 40)
        {
            System.out.println("Failed");
        }
        else if (examMark >= 40 && examMark <= 49)
        {
            System.out.println("3rd");
        }
        else if (examMark >= 50 && examMark <= 59)
        {
            System.out.println("2/2");
        }
        else if (examMark >= 60 && examMark <= 69)
        {
            System.out.println("2/1");
        }
        else if (examMark >= 70 && examMark <= 100)
        {
            System.out.println("1st");
        }
        else
        {
            System.out.println("Invalid Mark");
        }
        entry = (firstCap + " " + surCap + ", " + unit + ", " + examMark);
        //  out.println(entry);
        menuActions();
    }
    public static void viewGrades() {

        int i =1;

        String line;

        while ((line = reader.readLine()) != null) {
            System.out.println(i + ") " + line);    
            i++; 

        }
        menuActions();
    }
    public static void deleteGrades(){
        int i = 1;
        String line;
        File tempFile = new File("MyTempFile.txt");
        BufferedWriter writer = new BufferedWriter(new FileWriter(tempFile));
        System.out.println("Current Entries Stored: ");
        i =1;
        while ((line = reader.readLine()) != null) {
            System.out.println(i + ") " + line);    
            i++; 
        }

        Scanner scanner = new Scanner(System.in);
        System.out.print("To delete, please enter student's First Name: "); 
        firstNameDelete = scanner.nextLine();
        System.out.print("Now, please enter student's Surname: ");
        lastNameDelete = scanner.nextLine();
        reader.close();
        reader = new BufferedReader(new FileReader(deleteRecord));
        String currentLine = reader.readLine();

        while(currentLine != null) {
            if(!currentLine.contains(firstNameDelete) && !currentLine.contains(lastNameDelete)) {
                writer.write(currentLine);
                writer.newLine();
            }
            currentLine = reader.readLine();

        }
        System.out.print("if name matches, it will be deleted ");
        reader.close();
        writer.close();
        deleteRecord.delete();
        tempFile.renameTo(deleteRecord);
    }
    public static void exitProgram(){
        System.out.println("Thanks for using 'GradeEnter' ");
        System.exit(0);
        // Are you sure you want to exit gui?
    }

    public static void main(String[] args) throws Exception {
        System.out.println("Welcome to the 'GradeEnter' program! ");
        menuActions();
    }
}

我环顾四周，无法找到关于这个问题的任何事情。如果有人可以提供帮助，我将不胜感激。感谢

Answer 1

reader需要声明中的类型，变量deleteRecord在声明之前也会被使用 - 但是定义reader的语句会抛出一个已检查的异常，因此需要放置在代码块而不是类块

public class ExamGradesMethods {

    ...
    private void readRecords() throws FileNotFoundException {
        File deleteRecord = new File("GradeEnter.txt");
        BufferedReader reader = new BufferedReader(new FileReader(deleteRecord));
        ...
    }
}

阅读：Variables

此令牌后预期会出现VariableDeclartorID错误

1 个答案: