Question

我知道弄糟的是我的checkIfEdu方法。其他一切都很好，因为我没有那种方法就尝试过。但是，由于该方法，它正在将所有数据读入InvalidStudentEmails文件及其中！我知道，其他一切都很好，因为当我采取这种方法时，它会正确地完成所有事情。请帮忙!!!

import java.util.Scanner;
public class CheckStudentEmail
{
    public static void main (String[] args) throws Exception
    {
        java.io.File filein = new java.io.File("StudentEmailData.txt");
        java.io.File fileout1 = new java.io.File("ValidStudentEmails.txt");
        java.io.File fileout2 = new java.io.File("InvalidStudentEmails.txt");
        Scanner input = new Scanner(filein);
        java.io.PrintWriter validOutput = new java.io.PrintWriter(fileout1);
        java.io.PrintWriter invalidOutput = new java.io.PrintWriter(fileout2);

        writeHeadings(validOutput, invalidOutput);
        StudentEmail student = new StudentEmail();
        while (input.hasNext())
        {
                student.readStudentData(input);
                if (student.checkPeriod() == true && student.checkAtSymbol() == true
                   && student.checkIfEdu() == true)
                    student.writeEmails(validOutput);
                else
                    student.writeEmails(invalidOutput);
        }
        input.close();
        validOutput.close();
        invalidOutput.close();
    }

    public static void writeHeadings(java.io.PrintWriter validOutput,  java.io.PrintWriter invalidOutput)
    {
        validOutput.printf("%-20s%20s", "Name", "Email Address (Valid)");           validOutput.println();          validOutput.println();
            invalidOutput.printf("%-20s%20s", "Name", "Email Address (Invalid)");
            invalidOutput.println();
            invalidOutput.println();
        }

}

以下是我的方法

import java.util.Scanner;
public class StudentEmail
{
    private String stuName;
    private String stuEmail;

    StudentEmail()
    {}

    StudentEmail(String name, String email)
    {
        stuName = name;
        stuEmail = email;
    }

    public void readStudentData(Scanner input)
    {
        stuName = input.next();
        stuEmail = input.next();
    }

    public boolean checkPeriod()
    {
        if (stuEmail.indexOf(".") != -1)
            return true;
        else
            return false;
    }

    public boolean checkAtSymbol()
    {
        int atSymbol;
        if (stuEmail.indexOf('@') != -1)
        {
            atSymbol = stuEmail.indexOf('@');
            if (stuEmail.indexOf('@', atSymbol+1) != -1)
                return false;
            else
                return true;
        }
        else
            return false;
    }

    public boolean checkIfEdu()
    {
        int lengthOfEmail = stuEmail.length();
        int position = lengthOfEmail - 3;
        String checkWord = stuEmail.substring(position);
        if (checkWord == "edu")
            return true;
        else
            return false;
    }

    public void writeEmails(java.io.PrintWriter output)
    {
        output.printf("%-20s%20s", stuName, stuEmail);
        output.println();
    }

}

Answer 1

将字符串与equals（）方法进行比较。使用'=='比较对象引用

Answer 2

您是否检查了checkIfEdu() return的内容是什么？

另一件事是，因为我试图运行你的checkIfEdu()它总是返回false。因为您将其作为参考进行比较。

要比较字符串，这应该是这样的：

if (checkWord.equals("edu")) {

我无法弄清楚什么是错的，我的逻辑似乎是正确的

2 个答案: