ArrayList.Contains always return true, even the objects are not equal

[Jaykiran Teraiya]

Hi All,

I am using an ArrayList to store my CustomQuery objects. I am using .contains(customQuery) to compare weather the object is already present or not? If it's not there I am adding the object to the list.

The problem is list.contains(customQuery) always return false, even if the objects are equal(i.e. their id's are equal). I've also overrided .equals() and .hascode() method in my CustomQuery class.

  public String addCustomQueryToDownloadList(){
		
		ArrayList<CustomQuery> list = getSessionScopeBacking().getDownloadCustomQueryList();
		CustomQuery customQuery = getSessionScopeBacking().getSelectedCustomQuery();	
		boolean temp = list.contains(customQuery);
		if(!temp){
			list.add(customQuery);
		}
		return null;		

	
	}  

 @Override
	public boolean equals(Object obj) {
		if(this == obj) {
            return true;
       }
		CustomQuery customQuery = (CustomQuery) obj;
		if(customQueryId == customQuery.getCustomQueryId()){
			return true;
		}else return false;
	}
	
	@Override
	public int hashCode() {
		
		return Integer.valueOf(customQueryId)*2;
	}
   

Any help would be highly appriciated.

Thanks
Jay

[Abimaran Kugathasan]

What will happen if you use equals() method instead of using == in checking the customerQueryId?

[Jaykiran Teraiya]

Thanks, Worked like a charm..

[Abimaran Kugathasan]

And Welcome to JavaRanch!

[Jaykiran Teraiya]

Thank you for warm welcome.

[Rob Spoor]

Two things:

1) what will happen if I pass a String into the equals method? It will certainly compile.
2) do you really need a List? A Set makes sure of uniqueness; if the order is important then a LinkedHashSet will work as well.

[Jaykiran Teraiya]

my first choice was to use a Set, but I need to interact with other API and it accepts list as it's parameter. If I use set I need to convert set into list , so to avoid that conversion I used List.