Class array in constructor with reflection

Question

I need to use reflection in my code, so my program doesn't break with every different version. I want to create a new instance of a class and the constructor that I want to use contains an array of a class. But that class also has to be found using reflection. This is an example of what I currently have.

Constructor<?> constructor = getClass("className").getConstructor(getClass("anotherClass"));

private Class<?> getClass(String name) {
    return Class.forName("my.package." + version + "." + name);
}

However the constructor doesn't use that class, but an array of that class, so how would I turn this class into an array type of it?

Sotirios Delimanolis · Accepted Answer · 2016-05-01 16:13:57Z

6

The Java Virtual Machine specification specifies the class names for array types. You could construct such a name and use Class#forName. However, the logic for the names differs between primitive types and reference types, so it might get annoying generating those String names.

Instead, you can construct an array of size 0 for the given type and use it to retrieve its type with getClass().

For example

Class<?> componentType = Class.forName("java.lang.String");
Class<?> arrayType = java.lang.reflect.Array.newInstance(componentType, 0).getClass();
System.out.println(arrayType);

will print

class [Ljava.lang.String;

arrayType will then hold the Class object for the given array type. You can use it to retrieve the constructor.

edited May 1, 2016 at 16:13

answered Apr 29, 2016 at 15:22

Sotirios Delimanolis

281k62 gold badges718 silver badges744 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Class array in constructor with reflection

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related