Compare string within an array of objects

Question

i am new. Hope someone can help me.I want to compare a string from user input with a course title variable which is also a string type.The "course title" variable it's part of the state of a number of objects that are inserted in an array of objects.

Here is the code:

 if (selection.equals("yes")){
 System.out.print("");
 System.out.print("Enter the day of exam you want to search: ");
 int search= ScannerUtility.readInt();
 int i = 0;
line 43 while( i<a.length && search.equals(a[i].getCourseTitle()) ){
 i++;
 {

here the console error:

line 43: 
error: int cannot be dereferenced while( i<a.length && search.equals(a[i].getCourseTitle() ) ){

---

//Here is all the classes

I am italian, thus sorry if i don't translate properly.BTW here is the ManagementExams Class:

import java.util.*;
 public class ManagementExams{
 public static void main(String[] args){
 Scanner sc= new Scanner(System.in);
 System.out.println("MANAGEMENT EXAMS");
 System.out.print("Indicate how many exams do you want to insert: ");
 int dim = ScannerUtility.readInt();
 int nexams = 1;
 Exam [] a = new Exam[dim];
 for(int i=0; i<a.length; i++){
 System.out.print("Insert the name of the exam " + nexams +":");
 String coursetitle = sc.nextLine();
 System.out.print("Insert the day of the exam: ");
 int day = ScannerUtility.readInt();
 System.out.print("Insert the month of the exam: ");
 String month = sc.nextLine();
 System.out.print("Insert the year of the exam: ");
 int year = ScannerUtility.readInt();
 System.out.print("Insert the hour of the exam: ");
 int hourexam = ScannerUtility.readInt();
 Exam b = new Exam(coursetitle,day,month,year,hourexam);
 a[i] = b;
 nexams++;
 }
 System.out.print("The number of exams inserted are': " + (nexams-1)+ "\n\n");
 System.out.println("Print Exams: \n");
 for(int i=0; i<a.length; i++)
 System.out.println(a[i]);
 System.out.print("Do you want to change the day of certain exams?: ");
 String selection = sc.nextLine();
 if (selection.equals("yes")){
 System.out.print("");
 System.out.print("Insert the name of the exam you want to search: ");
 String search= ScannerUtility.readString();
 int i = 0;
 while( i<a.length && search.equals(a[i].getCourseTitle()) )
 i++;
 if(i<a.length){
 System.out.println("I found the following exam: \n" + a[i]);
 System.out.print("Change the day: ");
 int day= ScannerUtility.readInt();
 a[i].setDay(day);
 }
 else{
 System.out.println("No exam was found ");
 System.exit(0);
 }
 }
 else if(selection.equals("no"))
 System.exit(0);
 for(int i=0; i<a.length; i++)
 System.out.print("Mold the update data of the exams: \n" + a[i] +"\n");
 }
 }

Here the class Exam:

public class Exam{
 private String coursetitle;
 private int day;
 private String month;
 private int year;
 private int hourexam;
 //CONSTRUCTOR
 public Exam(String coursetitle,int day,String month,int year,int hourexam){
 this.coursetitle=coursetitle;
 this.day=day;
 this.month=month;
 this.year=year;
 this.hourexam=hourexam;
 }
 //SET METHODS
 public void setCourseTitle(String a){
 this.coursetitle=a;
 }
 public void setDay(int a){
 this.day=a;
 }
 public void setMonth(String a){
 this.month=a;
 }
 public void setYear(int a){
 this.year=a;
 }
 public void setHourExam(int a){
 this.hourexam=a;
 }
 //GET METHODS
 public String getCourseTitle(){
 return this.coursetitle;
 }
 public int getDay(){
 return this.day;
 }
 public String getMonth(){
 return this.month;
 }
 public int getYear(){
 return this.year;
 }
 public int getHourExam(){
 return this.hourexam;
 }
 //TOSTRING
 public String toString(){
 return coursetitle +"\n" + day + "\n" + month + "\n" + year +"\n" + hourexam;
 }
}

Both class build and compile correctly,but when i create an exam with the coursetitle like "math" and then i try to search it,with the string input "math" the program jump to the println method "no exam was found".

• Jacob Mattison: Can we see the definition of a?
• nachokk: search is a primitive type, you can't access to fields or methods..

Answer 1

search is an int which cannot be dereferenced (i.e. you cannot use . with it). It seems like using == may work if it is an integer, but perhaps getCourseTitle returns a string. In that case, convert the integer to a string.

while (i < a.length && Integer.toString(search).equals // etc.

• Valentin Ruano: Well spotted. It might be the the problem is some semantic bug as does not makes much sense to compare "exam days" with "course titles" We need the full code @ggianino
• Coder: i have updated the first post ;)..one thing what is that "Integer" that you used in the example?
• Valentin Ruano: @ggianino Integer is the int wrapper class java.lang.Integer. He is using it to access the static method toString therein implemented. ("" + search).equals would be as effective.
• Coder: Why should i convert an int value to a string value and viceversa? The problem it's located here: while( i<a.length && search.equals(a[i].getCourseTitle()) ).How can i compare the string value of user input with the coursetitle var in the Exam object?
• Explosion Pills: @ggianino Why are you using ScannerUtility.readInt then? That reads in an int...

Answer 2

//PROBLEM SOLVED ;)

import java.util.*;
public class ManagementExams{
 public static void main(String[] args){
 Scanner sc= new Scanner(System.in);
 System.out.println("MANAGEMENT EXAMS \n");
 System.out.print("Indicate how many exams do you want to insert: ");
 int dim = ScannerUtility.readInt();
 int nexams = 1;
 Exam [] a = new Exam[dim];
 for(int i=0; i<a.length; i++){
 System.out.println("");
 System.out.print("Insert the name of the exam " + nexams +":");
 String coursetitle = sc.nextLine();
 System.out.print("Insert the day of the exam: ");
 int day = ScannerUtility.readInt();
 System.out.print("Insert the month of the exam: ");
 String month = sc.nextLine();
 System.out.print("Insert the year of the exam: ");
 int year = ScannerUtility.readInt();
 System.out.print("Insert the hour of the exam: ");
 int hourexam = ScannerUtility.readInt();
 Exam b = new Exam(coursetitle,day,month,year,hourexam);
 a[i] = b;
 nexams++;
 }
 System.out.print("The number of exams inserted are: " + (nexams-1)+ "\n\n");
 System.out.println("Print Exams: \n");
 for(int i=0; i<a.length; i++){
 System.out.println(a[i].toString());
 }
 System.out.print("Do you want to change the day of certain exams?: ");
 String selection = sc.nextLine();
 if (selection.equals("yes")){
 System.out.print("");
 System.out.print("Insert the name of the exam you want to search: ");
 String search = ScannerUtility.readString();
 boolean var = false;
 for(int i=0; i < a.length; i++){
 if(search.equals(a[i].getCourseTitle()) ){
 var = true;
 System.out.println("I found the following exam: \n" + a[i].toString() );
 System.out.print("Change the day: ");
 int newday = ScannerUtility.readInt();
 a[i].setDay(newday);
 }
 }
 if(var == false ){
 System.out.println("No exam was found ");
 System.exit(0);
 }
 System.out.println("");
 for(int j=0; j < a.length; j++){
 System.out.println("Exams updated: \n" + a[j].toString() + "\n");
 }
 System.exit(0);
 }else if(selection.equals("no")){
 System.exit(0);
 }
 }
}