ArrayList error - Cannot find symbol

Question

I'm working on a final project for school and having some troubles. I have never done any programming in Java or really anything Object Oriented, so my code's likely not going to be that great.

I'm having some issues with my array list. I am getting an error that says cannot find symbol - class studentInfo. What am I doing incorrectly with my code? This is preventing me from compiling the code. All student info is fake.

Also would anyone have any recommendations on how to clean up or optimize my code?

import java.util.ArrayList;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Roster
{
   private static ArrayList<studentInfo> studentList = new ArrayList<>();

   public static void main(String[] args)
    {

        add(1, "John", "Smith", "John1989@gmail.com", 20, 88, 79, 59);
        add(2, "Suzan", "Erickson", "Erickson_1990@gmailcom", 19, 91, 72, 85);
        add(3, "Jack", "Napoli", "The_lawyer99yahoo.com", 19, 85, 84, 87);
        add(4, "Erin", "Black", "Erin.black@comcast.net", 22, 91, 98, 82);
        print_all();
        print_invalid_emails();
        print_average_grade(2);
        remove(3);
        remove(3);



    }
   public static void add (int studentID, String firstName, String lastName, String email, int age, int grade1, int grade2, int grade3)
   {
       int[] grades = {grade1, grade2, grade3};
       studentInfo newStudent = new studentInfo (studentID, firstName, lastName, email, age, grades);
       studentList.add(newStudent);
   }

  public static void remove(int studentID) 
  {
      for (studentInfo i: studentList) {
          if (i.getStudentID == studentID) {
              studentList.remove(i);
              System.out.println("Student Removed");
            } 
          else {
            System.out.println("A student with this ID(studentID) was not found.");
            return;
            }  

        }
  }
  public static void print_all (){
    for (studentInfo i: studentList) {
        studentList.get(i).print();
    }
  }
  public static void print_average_grade(int studentID) {
      studentList.get(studentID).getAverageGrade();
 }

 public static void print_invalid_emails() {
     String RFC5322 = "^[a-zA-Z0-9_!#$%&'*+/=?`{|}~^.-]+@[a-zA-Z0-9.-]+$";
     Pattern pattern = Pattern.compile(RFC5322);
     for (studentInfo i: studentList) {
         String email = i.getEmail;
         Matcher matcher = pattern.matcher(email);
         System.out.println(email +":\t"+ matcher.matches());
     }

 }


}

My second class

public class Student
{
    private int studentID;
    private String firstName;
    private String lastName;
    private String email;
    private int age;
    private int[] grades;

    public Student (int studentID, String firstName, String lastName, String email, int age, int grades[]) 
    {
    setStudentID(studentID);
    setFirstName(firstName);
    setLastName(lastName);
    setEmail(email);
    setAge(age);
    setGrades(grades);

    }

    public void setStudentID(int studentID) {
        this.studentID = studentID;
    }

    public void setFirstName(String firstName) 
    {
        this.firstName = firstName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public void setGrades(int[] grades) {
        this.grades = grades;
    }

    public int getStudentID() {
       return studentID;
    }

    public String getFirstName() {
       return firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public String getFullName() {
        return firstName + lastName;
    }

    public String getEmail() {
        return email;
    }

    public int getAge() {
        return age;
    }

    public int[] getGrades() {
        return grades;
    }

    public int getAverageGrade() {
        int averageGrade = 0;
            for (int grade : grades) {
                averageGrade += grade;
            }
        return averageGrade;
    }
    public void print() {
        System.out.println(
        "Student Name:\t" + getFullName() + "\n " + 
        "Student ID:\t" + getStudentID() + "\n" + 
        "Email:\t" + getEmail() + "\n" + 
        "Age:\t" + getAge() + "\n" +
        "Average Grade:\t" + getAverageGrade()
        );

    }


}

Do you mean `Student` instead of `studentInfo`? – Andy Turner Apr 30 '17 at 20:47 — Andy Turner, Apr 30 '17 at 20:47

score 1 · Accepted Answer · answered Apr 30 '17 at 21:08

I made the following changes to your code:

ArrrayList should store object of type Student. studentInfo does not refer to any defined class.
In method add, change type of newStudent to Student.
Make the same necessary adjustments in the for-loops in the remove, print_all and print_invalid_emails methods.

The corrected code is shown below:

import java.util.ArrayList;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Roster
{
   private static ArrayList<Student> studentList = new ArrayList<>();

   public static void main(String[] args)
    {

        add(1, "John", "Smith", "John1989@gmail.com", 20, 88, 79, 59);
        add(2, "Suzan", "Erickson", "Erickson_1990@gmailcom", 19, 91, 72, 85);
        add(3, "Jack", "Napoli", "The_lawyer99yahoo.com", 19, 85, 84, 87);
        add(4, "Erin", "Black", "Erin.black@comcast.net", 22, 91, 98, 82);
        print_all();
        print_invalid_emails();
        print_average_grade(2);
        remove(3);
        remove(3);    
    }

   public static void add (int studentID, String firstName, String lastName, String email, int age, int grade1, int grade2, int grade3)
   {
       int[] grades = {grade1, grade2, grade3};
       Student newStudent = new Student (studentID, firstName, lastName, email, age, grades);
       studentList.add(newStudent);
   }

  public static void remove(int studentID) 
  {
      for (Student i: studentList) {
          if (i.getStudentID() == studentID) {
              studentList.remove(i);
              System.out.println("Student Removed");
            } 
          else {
            System.out.println("A student with this ID(studentID) was not found.");
            return;
            }  

        }
  }
  public static void print_all (){
    for (Student i: studentList) {
        i.print();
    }
  }
  public static void print_average_grade(int studentID) {
      studentList.get(studentID).getAverageGrade();
 }

 public static void print_invalid_emails() {
     String RFC5322 = "^[a-zA-Z0-9_!#$%&'*+/=?`{|}~^.-]+@[a-zA-Z0-9.-]+$";
     Pattern pattern = Pattern.compile(RFC5322);
     for (Student i: studentList) {
         String email = i.getEmail();
         Matcher matcher = pattern.matcher(email);
         System.out.println(email +":\t"+ matcher.matches());
     }

 }


}

This was exactly it! I found that I kept getting some errors when changing it to Student instead of StudentInfo because I was using, for example, i.getEmail which was referencing as a variable versus i.getEmail() for the method. — gmart, Apr 30 '17 at 21:11
Glad it worked for you. Don't forget to upvote too :D Exaxtly so. Omitting the brackets in method calls is a very common coding error — Ekaba Bisong, Apr 30 '17 at 21:18

ArrayList error - Cannot find symbol

1 Answers1