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);
        }
}

What error did you get?

Raedwald
– Raedwald

2015-04-02 07:10:57 +00:00
Commented Apr 2, 2015 at 7:10 — Raedwald
– Raedwald, Commented Apr 2, 2015 at 7:10

Rahul · Accepted Answer · 2013-10-27 10:28:20Z

47

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

edited Oct 27, 2013 at 10:28

answered Oct 27, 2013 at 10:22

Rahul

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1 Comment

Alexis C. Over a year ago

Also the OP should write a constructor in his class.

Rahul · Accepted Answer · 2014-03-19 13:04:37Z

1

Try this one:

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

edited Mar 19, 2014 at 13:04

Rahul

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answered Oct 27, 2013 at 11:00

Umar Asghar

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Comments

RubioRic · Accepted Answer · 2018-05-25 10:33:13Z

1

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);

edited May 25, 2018 at 10:33

RubioRic

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answered Jan 6, 2016 at 5:40

saibaba vali

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Comments

James Skemp · Accepted Answer · 2015-08-08 15:26:21Z

0

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

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

edited Aug 8, 2015 at 15:26

James Skemp

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answered May 30, 2014 at 11:57

Prashant Bhagwani

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Comments

Rajeev Sreedharan · Accepted Answer · 2021-08-14 17:21:24Z

0

The best way to pass data to class List,

private final List<electronic> Electronic = new ArrayList<electronic>();

public List<electronic> getElectronic() {
    return Electronic;
}

// creating list to store and display the Electronic items
public void StoreAndDisplayElectronic() {
    String[] EelctronicName = { "Laptop", "Television", "ElectricBike" };
    String[] ElectronicID = { "091", "202", "151" };
    Double[] EPrice = { 340.00, 280.00, 600.00 };
    int[] EAmt = { 5, 12, 4 };

    for (int i = 0; i < ElectronicID.length; i++) {
        this.Electronic.add(new electronic(EelctronicName[i], ElectronicID[i], EPrice[i], EAmt[i]));
    }
}

edited Aug 14, 2021 at 17:21

Rajeev Sreedharan

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answered Aug 14, 2021 at 6:03

Abdullah Arif

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Comments

Joaquín · Accepted Answer · 2021-11-06 12:09:27Z

0

You don't return a Data Object when call 'Data()' method.

Change 'Data()' method to:

    public Data Data(String n, String a, String c){
        name = n;
        address = a;
        cell = c;
        return this;
    }

answered Nov 6, 2021 at 12:09

Joaquín

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Comments

moha · Accepted Answer · 2015-02-22 03:25:19Z

-1

change Date to Object which is between parenthesis

answered Feb 22, 2015 at 3:25

moha

1

2 Comments

Jonathan Over a year ago

What Date? This doesn't look like a solution to me.

James Skemp Over a year ago

I think they meant Data but it doesn't look this user is coming back.

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