How to delete an entry from a Map?

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www - 16 Nov 2007 20:36 GMT

Hi,

I cannot figure out how to delete an entry from a Map(HashMap). For
example, suppose I have a class Person and 3 objects of that
type(personA, personB and personC):

public class Person {
    private String name;

    ....//

    public String getName{
        return name;
    }
}

personA is with name of "John", personB and personC are with other names.

Map<Person> map = new HashMap<Person>();

//so easy to add to Map
map.add(personA);
map.add(personB);
map.add(personC);

...

//now, I want the map only has the guy with name of "John", i.e. I want
to delete personB and personC from map. I felt that it is so difficult.

Thank you for your help.

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Eric Sosman - 16 Nov 2007 21:00 GMT

www wrote On 11/16/07 15:36,:

> Hi,
>
[quoted text clipped - 25 lines]
> //now, I want the map only has the guy with name of "John", i.e. I want
> to delete personB and personC from map. I felt that it is so difficult.

You say you're using a Map, but your code sample seems
to be using a Set (and calling it a Map).

If it's a Map, you would have something like

    Map<String,Person> map = new HashMap<String,Person>();
    // add Persons:
    map.put(personA.getName(), personA);
    map.put(personB.getName(), personB);
    map.put(personC.getName(), personC);
    // remove two of them:
    map.remove(personB.getName());
    map.remove(personC.getName());

If it's a Set, it would look like

    Set<Person> set = new HashSet<Person>();
    // add Persons:
    set.add(personA);
    set.add(personB);
    set.add(personC);
    // remove two of them:
    set.remove(personB);
    set.remove(personC);

Signature

Eric.Sosman@sun.com

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Robert Klemme - 17 Nov 2007 23:17 GMT

> Hi,
>
[quoted text clipped - 27 lines]
>
> Thank you for your help.

Read the Javadoc.

robert

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How to delete an entry from a Map?

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