New instance of an arbitrary class [duplicate]

Question

This question already has answers here:

Dynamically create classes in Java (4 answers)

Closed 9 years ago.

In Java, how can I create a new instance of a class, where the class is not selected until the code is run?

List<Class> classes = new ArrayList<>();
classes.add(String.class);
classes.add(ArrayList.class);
classes.add(Integer.class);
classes.add(Random.class);

Random r = new Random();
Class c = classes.get(r.nextInt(classes.size()));

Object o = // new instance of "c"

Answer 1

If you know that the class has a no-arg constructor you can just call c.newInstance(). Otherwise you need to call the overloaded version of newInstance() which accepts arguments.

Answer 2

Try in this way but not a good way.

Class<?> clazz = String.class;
Constructor<?> ctor = clazz.getConstructor(String.class);
Object object = ctor.newInstance(new Object[] { "abc" });

System.out.println(object); // print abc