使用参数化构造函数实例化一组给定的类

Question

Is it possible in Java to take a collection of classes with parameterized constructors and instantiate each one of them at run time? These classes have only one constructor that can take any number of primitive type arguments, though the number of arguments they take can vary for each class. As an example, here are four classes that we want to instantiate at run time:

 public class One { public One(int a) { } }
 public class Two { public Two(char a, int b) { } }
 public class Three { public Three(float a, char b, int c) { } }
 public class Four { public Four(float a, char b, int c) { } }

Answer 1

Class oneC = Class.forName("One"); // use FQCN
Contructor constructor = oncC.getConstructors()[0]; // assuming that the class has only 1 constructor
Class<?>[] paramTypes = constructor.getParameterTypes();
// Iterate paramTypes, create each parameter value and then call constructor.newInstance(...)

Reference:

• Constructor#getParameterTypes()
• Class#getConstructors()