Why aren't Java Collections remove methods generic?

Question

Why isn\'t Collection.remove(Object o) generic?

Seems like Collection could have boolean remove(E o);

Then, when you ac

Answer 1

In addition to the other answers, there is another reason why the method should accept an Object, which is predicates. Consider the following sample:

class Person {
    public String name;
    // override equals()
}
class Employee extends Person {
    public String company;
    // override equals()
}
class Developer extends Employee {
    public int yearsOfExperience;
    // override equals()
}

class Test {
    public static void main(String[] args) {
        Collection people = new ArrayList();
        // ...

        // to remove the first employee with a specific name:
        people.remove(new Person(someName1));

        // to remove the first developer that matches some criteria:
        people.remove(new Developer(someName2, someCompany, 10));

        // to remove the first employee who is either
        // a developer or an employee of someCompany:
        people.remove(new Object() {
            public boolean equals(Object employee) {
                return employee instanceof Developer
                    || ((Employee) employee).company.equals(someCompany);
        }});
    }
}

The point is that the object being passed to the remove method is responsible for defining the equals method. Building predicates becomes very simple this way.