リフレクション

import java.lang.reflect.*;

Class<?> clazz = String.class;

// Get class name
System.out.println(clazz.getName());
System.out.println(clazz.getSimpleName());

// Get fields
for (Field field : clazz.getDeclaredFields()) {
    System.out.println(field.getName() + ": " + field.getType());
}

// Get methods
for (Method method : clazz.getDeclaredMethods()) {
    System.out.println(method.getName());
}

// Dynamically create instance
Object obj = clazz.getConstructor(String.class).newInstance("Hello");

// Dynamically invoke method
Method m = clazz.getMethod("length");
int len = (int) m.invoke(obj);