CODEWITHSUNDEEP
javamethodsarraylist
user1157649
user1157649

Reputation: 23

Equal Method: Comparing 2 Objects

I am currently working on a project in java. I need to create a method that compares two items by name. My first file is called Item which has a name. The second file has an arrayList of Items. I need to create an equal method which compares two items based on their name. I need to return a boolean and the code starts with this.

public boolean toEqual(Object o)

I am confused about what to do next. I know you will probably have to use an if else statement as well as the getName() method I created. However I think am supposed to cast the object as an Item object but I don't know how. Can anyone suggest anything? Thanks.

Upvotes: 2

Views: 204

Answers (4)

Rannnn
Rannnn

Reputation: 582

Let's say you have a class called Item And your Item class have an instance field called name which you use it to store the name of the item.

class Item {
    private String name = "item name";

    public String getName() {
        return name
    }

    public boolean toEqual(Object o) {
        // Firstly cast it to Item
        Item item = (Item) o;
        // Then perform the compare
        return (name.equals(item.getName()));
    }
}

Actually you can change the signature of toEqual method to public boolean toEqual(Item o). In this case you will not need the cast operation.

public boolean toEqual(Item o) {
    // Perform the compare
    return (name.equals(o.getName()));
}

Upvotes: 0

joe_coolish
joe_coolish

Reputation: 7259

You are correct on what to do, and so now you just need to put it together.

http://www.javabeginner.com/learn-java/java-object-typecasting That site has some info on casting objects in Java. Basically to case one object to another, you do something like this:

Item i = (Item) o;

That will cast your o to type Item

Next you need to see if i.getName().equals(getName()). You can return that result and you should be done :)

Good luck!

Upvotes: 2

Web User
Web User

Reputation: 7736

You should implement the boolean equals(Object) and int hashCode() for the item class, because then you can simply invoke the contains(Object) method of the list to find if a matching item exists in the list.

Upvotes: 0

Manish
Manish

Reputation: 1836

You can cast object like this - 

(ClassName)obj

However, a much better approach would be to override equals & hashcode methods of java.lang.Object and handle it there. To know how to override it correctly, you can refer to this article - http://www.technofundo.com/tech/java/equalhash.html

HTH, - Manish

Upvotes: 1

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