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Thread: How to test if class/object is immutable

  1. #1
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    Default How to test if class/object is immutable

    I have make the immutable class as below, Now my question is how I can test if my this class/object is immutable

    package com.learning;

    import java.util.*;
    import java.util.Map.Entry;

    public final class ImmutableTest {

    private final int id;
    private final String name;
    private final HashMap<String, String> hm ;

    public int getId() {
    return id;
    }
    public String getName() {
    return name;
    }
    public HashMap<String, String> getHm() {
    return (HashMap<String, String> )hm.clone();
    }

    public ImmutableTest(HashMap<String, String> hm, int id, String name) {
    super();
    HashMap<String, String> temp = new HashMap<String, String>();
    this.id = id;
    this.name = name;
    Set<Entry<String, String>> s = hm.entrySet();
    Iterator<Entry<String, String>> itr = s.iterator();
    while(itr.hasNext()){
    Map.Entry<String, String> inentry = itr.next();
    temp.put(inentry.getKey(), inentry.getValue());
    }

    this.hm=temp;
    }

    }


    How I can Test If it is immutable class without looking ?


  2. #2
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    Default Re: How to test if class/object is immutable

    Can you define what you mean with an "immutable" class?
    Your class contains a hashmap which any outside user has access to. This means the contents of your hashmap can change over time. I would, personally, not say that this class is immutable, but if you define immutable different then thats your opinion.

  3. #3
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    Default Re: How to test if class/object is immutable

    immutable object (it cannot be changed once it's created). you mau always correct me if im wrong

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    Default Re: How to test if class/object is immutable

    Well, "changed" is a very broad definition.
    The name and id can not be changed, but the contents of the hasmap can. Do you count that as being changed?

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    Default Re: How to test if class/object is immutable

    That exactly was my question how may I test it if the above class is immutable or not

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    Default Re: How to test if class/object is immutable

    Please post your code correctly.

  7. #7
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    Default Re: How to test if class/object is immutable

    This is my code only, i need to know two things
    1) Whats wrong in my code
    2) how may i test my immutable class

    import java.util.*;
    import java.util.Map.Entry;

    public final class ImmutableTest {

    private final int id;
    private final String name;
    private final HashMap<String, String> hm ;

    public int getId() {
    return id;
    }
    public String getName() {
    return name;
    }
    public HashMap<String, String> getHm() {
    return (HashMap<String, String> )hm.clone();
    }

    public ImmutableTest(HashMap<String, String> hm, int id, String name) {
    super();
    HashMap<String, String> temp = new HashMap<String, String>();
    this.id = id;
    this.name = name;
    Set<Entry<String, String>> s = hm.entrySet();
    Iterator<Entry<String, String>> itr = s.iterator();
    while(itr.hasNext()){
    Map.Entry<String, String> inentry = itr.next();
    temp.put(inentry.getKey(), inentry.getValue());
    }

    this.hm=temp;
    }

    }

  8. #8
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    Default Re: How to test if class/object is immutable

    Please read this topic to learn how to post code correctly and then correct the post above.

  9. #9
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    Default Re: How to test if class/object is immutable

    thanks for correcting me,I have read the article, so here is my questions

    [Query]
    Below I have written the immutable class, Please let me know
    1) Whats wrong in my code
    2) how may i test my immutable class
    [/Query]

     
    import java.util.*;
    import java.util.Map.Entry;
     
    public final class ImmutableTest {
     
    private final int id;
    private final String name;
    private final HashMap<String, String> hm ;
     
    public int getId() {
    return id;
    }
    public String getName() {
    return name;
    }
    public HashMap<String, String> getHm() {
    return (HashMap<String, String> )hm.clone();
    }
     
    public ImmutableTest(HashMap<String, String> hm, int id, String name) {
    super();
    HashMap<String, String> temp = new HashMap<String, String>();
    this.id = id;
    this.name = name;
    Set<Entry<String, String>> s = hm.entrySet();
    Iterator<Entry<String, String>> itr = s.iterator();
    while(itr.hasNext()){
    Map.Entry<String, String> inentry = itr.next();
    temp.put(inentry.getKey(), inentry.getValue());
    }
     
    this.hm=temp;
    }
     
    }
     
    [B][/B]

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