pass class as parameter for a method in java

Question

Im trying to make a method that creates a new object of a class, but I want to be able to make objects of many different classes, so making a method for each class won't work for me. Is there any way I can pass in a class to a method, so that a new object can be created? All of my classes have the same constructor.

Answer 1

You could use

public <T> T instanciate(Class<? extends T> clazz) throws Exception {
    return clazz.newInstance();
}

and call it like

MyObject o = instanciate(MyObject.class);

If you do it that way, the classes you want to instanciate must have a default constructor with no argument. Otherwise, you'll catch a java.lang.InstantiationException.

Answer 2

Have you read about Abstract Factory pattern?

EDITED

BTW, I do not think that reflection is good way to make your architecture, if you have a lot of classes with the same constructor try to use useful patters like Factory or Builder instead of creating one method with reflection.

Answer 3

You can use reflection to switch on a type name and do what you gotta do.

Answer 4

I believe that you are looking for reflection.

Check out this question: What is reflection and why is it useful?

Answer 5

I think that Class.forName might be what you're looking for

Answer 6

package com.loknath.lab;

public class HasHash {

public static void main(String[] args) throws Exception {

  HasHash h = createInstance(HasHash.class);      
            h.display();

} //return the instance of Class of @parameter

public static T createInstance(Class className) throws Exception { return className.newInstance(); }

private void display() { System.out.println("Disply "); }

}