Java, how to convert a string to class and call its static method?

Question

class Item
{
    public static test()
    {
    }
}

String s = "package.Item";
Item o = (Item)Class.forName(s).cast(Item.class); // *
o.test();

but the marked line fails:

java.lang.ClassCastException: Cannot cast java.lang.Class to items.Item

`Class.forName()` returns a `Class` object, not an instance of that class. — Marko Topolnik, Oct 07 '16 at 14:04
And you won't be able to call the `test` method like that, you'll have to use Reflection. — Marko Topolnik, Oct 07 '16 at 14:06
Why do you want instance if the method is static? Does it make sense ? — Rahman, Oct 07 '16 at 14:10
Jesus whats up with people and the down votes. This is not a bad question at all. Actually its pretty much of something to keep in mind and learn about i will love for the proper answer so that i can implement this next time! — JT4U, Oct 07 '16 at 14:41

talex · Accepted Answer · 2016-10-07T14:14:44.653

1

To create new instance you need to do the following

Class c = Class.forName("Item");
Item i = (Item)c.newInstance();

If you want to invoke static method you just call it on class instead of instance

Item.test();

Or you can use reflection without directly reference to class

Class c = Class.forName("Item");
Method method = c.getMethod("test");
method.invoke(null);

edited Oct 07 '16 at 14:14

answered Oct 07 '16 at 14:06

talex

1

He can't call Item.test() since he receive Item into a String.. he need reflexion to get the methods (test) from the Class – AxelH Oct 07 '16 at 14:09
1

In his sample code he use `Item`. Of course his code doesn't have sense, but I work with what I have. – talex Oct 07 '16 at 14:11
It's in the title `how to convert a string to class and call its static method?` Item that he tried to create from the String ;) – AxelH Oct 07 '16 at 14:12
1

I added reflection code for completeness. – talex Oct 07 '16 at 14:15
1

It is a duplicated question ... no need for an answer ;) – AxelH Oct 07 '16 at 14:18
1

It is poorly stated question :) – talex Oct 07 '16 at 14:20
yes, there was a need for an answer... I coulnt know that I need this line too: "Method method = c.getMethod("test");", I thought somehow c.test can be invoked, by casting – John Smith Oct 07 '16 at 14:27

1 Answers1