Thread: 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 ?

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.

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

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?

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

Please post your code correctly.

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;
}

}

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

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]