java: how to get singleton instance by classloader

Question

Assume, I load the class by the ClassLoader at the runtime:

Class<MyInterface> clazz = (Class<MyInterface>)getClass().getClassLoader().loadClass("ImplementerOfMyInterface");

The new instance I can create then by

MyInterface myInt = clazz.newInstance();

But when I need to get the instance of the singleton by its name that implements the MyInterface instead of creating the new one, what should be done?

Fields have names, but Instances don't have names. Can you give an example of what you mean? — Peter Lawrey
– Peter Lawrey, Commented Jun 15, 2012 at 11:25

ewan.chalmers · Accepted Answer · 2012-06-15 11:25:40Z

3

Instead of invoking newInstance, you could invoke a static "getInstance" method (or whatever singleton getter method name you use).

For example:

public class ReflectTest {

    public static void main(String[] args) throws Exception {
        Class clazz = Class.forName("ReflectTest");
        Method m = clazz.getDeclaredMethod("getInstance", null);
        Object o = m.invoke(null, null);
        System.out.println(o == INSTANCE);
    }

    public static ReflectTest getInstance() {
        return INSTANCE;
    }

    private static final ReflectTest INSTANCE = new ReflectTest();

    private ReflectTest() {
    }

}

answered Jun 15, 2012 at 11:25

ewan.chalmers

16.3k47 silver badges62 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

java: how to get singleton instance by classloader

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related