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How to add an object to an ArrayList in Java


Question

I want to add an object to an ArrayList, but each time I add a new object to an ArrayList with 3 attributes: objt(name, address, contact), I get an error.

import java.util.ArrayList;
import java.util.Scanner;
public class mainClass {
    public static void main(String args[]){

        Scanner input = new Scanner(System.in);
        System.out.println("Plz enter Name : ");
        String name = input.nextLine();
        System.out.println("Plz enter Address : ");
        String address = input.nextLine();
        System.out.println("Plz enter ContactNo : ");
        String contact = input.nextLine();


        ArrayList<Data> Contacts = new ArrayList<Data>();
        Data objt = new Data();
        Contacts.add(objt.Data(name, address, contact));
    }
}

Here, Data is the class of which I'm trying to create an object and pass it to an ArrayList.

public class Data {

        private String name = "";
        private String address = "";
        private String cell = "";


        public void Data(String n, String a, String c){

            name = n;
            address = a;
            cell = c;
        }
        public void printData(){

            System.out.println("Name\tAddress\tContactNo");
            System.out.println(name + "\t" + address + "\t" + cell);
        }
}
2016/07/20
1
20
7/20/2016 8:11:22 PM

Accepted Answer

You need to use the new operator when creating the object

Contacts.add(new Data(name, address, contact)); // Creating a new object and adding it to list - single step

or else

Data objt = new Data(name, address, contact); // Creating a new object
Contacts.add(objt); // Adding it to the list

and your constructor shouldn't contain void. Else it becomes a method in your class.

public Data(String n, String a, String c) { // Constructor has the same name as the class and no return type as such
2013/10/27
41
10/27/2013 10:28:20 AM

Try this one:

Data objt = new Data(name, address, contact);
Contacts.add(objt);
2014/03/19

Contacts.add(objt.Data(name, address, contact));

This is not a perfect way to call a constructor. The constructor is called at the time of object creation automatically. If there is no constructor java class creates its own constructor.

The correct way is:

// object creation. 
Data object1 = new Data(name, address, contact);      

// adding Data object to ArrayList object Contacts.
Contacts.add(object1);                              
2018/05/25

You have to use new operator here to instantiate. For example:

Contacts.add(new Data(name, address, contact));
2015/08/08

change Date to Object which is between parenthesis

2015/02/22