Is there a way to update a record in an Arraylist without deleting the existing record?

Question

I have an arraylist , where records are stored as objects. I want to know if there is a way to update a record in an array list without deleting the existing record?

For example, my records have attributes like first name, last name, initials, id etc. Is there a way to update the first name in a record, instead of having to give all the other attributes values as well?

Currently what I have done is when the user gives an id, I find it whether the id matches any record in the array and if it does, I delete it off the array and make the user enter all the details from the beginning.

Answer 1

Arraylist stores the reference and does not copy/create new objects. If you change the stored object reference, it will be reflected in the arrayList as well. Here is a sample code to demonstrate that:

package arraylistExample;

import java.util.ArrayList;

/**
 * Class represeting entity to be stored in Arraylist 
 * 
 */
class Person {

private String name;
private int age;
private String address;

public Person(String name, int age, String address) {
    super();
    this.name = name;
    this.age = age;
    this.address = address;
}

public String getName() {
    return name;
}
public void setName(String name) {
    this.name = name;
}
public int getAge() {
    return age;
}
public void setAge(int age) {
    this.age = age;
}
public String getAddress() {
    return address;
}
public void setAddress(String address) {
    this.address = address;
}

@Override
public String toString() {
    return "Person [name=" + name + ", age=" + age + ", address=" + address
            + "]";
}


}

.

/**
 * Public class to run the demo
 *
 */
public class ArraylistObjectModify {

public static void main(String args[]) {

    // Add an arraylist and add elements to it
    ArrayList<Person> personList = new ArrayList<Person>();
    personList.add(new Person("Juned",32,"Bangalore"));
    personList.add(new Person("Ahsan",31,"Delhi"));
    personList.add(new Person("Sniper",1,"Grave"));

    //Print list elements before change
    System.out.println("Arraylist pre objects modification");
    System.out.println("----------------------------------");
    for(Person person:personList) {
        System.out.println(person);
    }

    for(Person person:personList) {
        if(person.getName().equals("Juned")) {
            person.setName("ChangedJuned");
            person.setAddress("Hola-lulu");
        }
    }

    //Print list elements after change
    System.out.println("Arraylist post objects modification");
    System.out.println("----------------------------------");
    for(Person person:personList) {
        System.out.println(person);
    }


}

}