Why does my program not recognize two objects as equal when they have the same values?

Question

I have three classes in my program: Person, Main, and SearchTool. I have an ArrayList of Person objects inside my Main class called personList. I am trying to use a method in SearchTool called search() to find a Person object inside personList.

Here is my search() method inside the SearchTool class:

public T search(T target, ArrayList<T> list) {
        for (int x = 0; x < list.length(); x++) {
            T obj = list.get(x);
            if (obj.equals(target)) {
                return obj;
            }
        }
        return null;
    }

Here is the driver code I have been testing this method with:

SearchTool<Person> searchTool = new SearchTool<Person>();
Person target = new Person("a", 5);
Person result = searchTool.search(target, list);
System.out.println(result);

However when I do this all that I get is null. I do have a toString() inside my Person class that prints the name and age, by the way. Please help me, I am very stuck here and nothing I try seems to work.

Edit: as per request, here is my Person class. I have removed the get and set methods for ease of reading.

package testing;

public class Person implements Comparable<Person> {
    private String name;
    private int age;
    public Person(String name, int age) {
        this.name = name;
        this.age = age;
    }
    public Person(Person p) {
        this(p.name, p.age);
    }
    public boolean equals(Person p) {
        if (this.getName().equals(p.getName()) && this.getAge() == p.getAge()) {
            return true;
        }
        else {
            return false;
        }
    }
    @Override
    public int compareTo(Person p) {
        return this.name.compareTo(p.name);
    }
    public String toString() {
        return "Name: " + name + "\nAge: " + age + "\n\n";
    }   
}

Edit: it seems like I did not override the Object class by referring to a Person object in my equals() method. I have corrected this by adding an Object as a parameter and casting it to Person. Thank you everyone for your help.

I would assume `Person` does not override `Object.equals(Object)`, but since you didn't post `Person` we can only assume. — Elliott Frisch, Feb 29 '20 at 19:40
To get better help don't *only* describe your code, show it instead (preferably as [mcve]). — Pshemo, Feb 29 '20 at 19:41
As @ElliottFrisch assumed, you're not overriding the `equals` method. — Federico klez Culloca, Feb 29 '20 at 19:44
Lists use `equals` method of elements to determine of they are equal, not `compareTo`. — Pshemo, Feb 29 '20 at 19:44
please copy the whole null error with stack trace here please. — vionixt, Feb 29 '20 at 19:47
@FedericoklezCulloca I added a equals method to the Person class, but it still prints out null. — Ben Foley, Feb 29 '20 at 19:51
@vionixt no, but I did just add an equals method in my Person class and it did not do anything — Ben Foley, Feb 29 '20 at 19:51
@BenFoley you added a second method overload for equals, you didn't override it. The method signature of equals is `boolean equals(Object other)` – you have `Person other` — knittl, Feb 29 '20 at 19:51
@BenFoley You are not overriding the `equals()` method from the `Object` class, see the linked question. — Progman, Feb 29 '20 at 19:52
you need to consider the hashcode as well. Please see [this](https://stackoverflow.com/questions/2265503/why-do-i-need-to-override-the-equals-and-hashcode-methods-in-java) — vionixt, Feb 29 '20 at 19:54
knittl and @progman thank you guys, this helped me tremendously. — Ben Foley, Feb 29 '20 at 19:54

Why does my program not recognize two objects as equal when they have the same values?

0 Answers0