Removing object from ArrayList

Question

I have written my own class called Person with the variables String name, int age and double height, as well as a toString(). I have then created an ArrayList of Persons, and added a couple of instances. It prints well. Now I want to write a method that, when I write a name, checks the ArrayList for instances with that name, an if so, removes that instance. How should I do this?

Here is what I've written:

import java.util.*;
public class PersonManager {

    public static void main(String[] args) {
        ArrayList<Person> people = new ArrayList<>();
        Scanner keyboard = new Scanner(System.in);

        people.add(new Person("Adam ", 29, 177.5));
        people.add(new Person("Bernadette", 19, 155.2));
        people.add(new Person("Carl", 45, 199));

        for (Person p : people)
            System.out.println(p);

        System.out.println("Select person to remove");
        String name = keyboard.nextLine();


        // if there is a person with that name in the list, that
        //person gets removed from the list

    }

}

Looks like you already know how to loop through an ArrayList. What do you know about comparing two String objects? — CubeJockey
– CubeJockey, Commented May 20, 2015 at 20:12
Take a look at the methods of ArrayList, see what the opposite of add might be and give it a try. If it doesn't work, show what you tried and we can help. — Always Learning
– Always Learning, Commented May 20, 2015 at 20:14

Master Mind · Accepted Answer · 2015-05-20 20:26:38Z

1

If you are using JAVA 8 and don't mind of creating a new List from the original you can use JAVA 8 stream like that :

    ArrayList<Person> people = new ArrayList<>();

    people.add(new Person("Adam ", 29, 177.5));
    people.add(new Person("Bernadette", 19, 155.2));
    people.add(new Person("Carl", 45, 199));
    String nameToRemove = "name";
    people = people.stream().filter((t) -> !t.getName().equals(nameToRemove)).collect(Collectors.toList());

answered May 20, 2015 at 20:26

Master Mind

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Comments

Priidu Neemre · Accepted Answer · 2017-07-17 06:45:15Z

1

As @MasterMind said: if you have access to JDK 8 features, you can either use filtering (as shown in his example) or alternatively, use the new Collection#removeIf(..) method. In your case, that would be something like:

people.removeIf(person -> person.getName().equals(name));

See here for a fully working example.

edited Jul 17, 2017 at 6:45

answered Jul 17, 2017 at 0:59

Priidu Neemre

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hitz · Accepted Answer · 2015-05-20 20:22:16Z

0

You want to navigate to Person with given name and remove it from the list.
So you can use iterator while going through list:

Iterator personIter = people.iterator();
while(personIter.hasNext()){
    Person p = (Person)personIter.next();    
    if(name != null && name.equals(p.getName())){
        personIter.remove();
        break; //will prevent unnecessary iterations after match has been found
    }
}

answered May 20, 2015 at 20:22

hitz

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