How to get a Class Object from the Class Name in J

问题:

I know the class name, say "MyClass" and want to retrieve the Class object, ie. MyClass.class for future references. Is there a way to do that?

I've looked through the web but most of the things I found related to it were about the ClassLoader, which I presume are not suitable for my case. I do not want to initialize a class, but only get a class object for future uses.

EDIT: Regarding the first answers to this:

I've already checked the forName() method but I thought that is supposed to also initialize the class. Now I can call it with the full arguments and pass false to the second argument, but would the third have to be null or what?

Would

Class.forName("MyClass", false, null);

return MyClass.class?

In fact, what I want to do, is replace an array of String IDs associated with Class objects, with an array of IDs from which the class objects are fetched automatically, to get rid of some manual work :)

Thanks for the quick answers and sorry for not mentioning this before.

回答1:

You can use:

Class c = Class.forName("com.package.MyClass");

And later instantiate an object:

Object obj = c.newInstance();

EDIT: This is just the simplest use case. As indicated in the comments, you will need to consider constructor arguments and exceptions thrown by the initialization process. The JavaDocs for newInstance has all the details.

回答2:

Class.forName("MyClass")

Read the JavaDoc for details

回答3:

It sounds like you might be able to use the Class class's static forName method.

回答4:

It's also worth noting that the above suggestions are correct, but will only work for default (parameterless) constructors. You could also do something like:

    public Object newInstance(String className, Object...args) throws Exception {
        Class<?> clazz = Class.forName(className);
        if(args == null || args.length == 0) {
            return clazz.newInstance();
        }

        List<Class<?>> argTypes = new ArrayList<Class<?>>();
        for(Object object : args) {
            argTypes.add(object.getClass());
        }
        Constructor<?> explicitConstructor = clazz.getConstructor(argTypes.toArray(new Class[argTypes.size()]));
        return explicitConstructor.newInstance(args);
    }