Can I use Class.newInstance() with constructor arguments?

I would like to use Class.newInstance() but the class I am instantiating does not have a nullary constructor. Therefore I need to be able to pass in constructor arguments. Is there a way to do this?

MyClass.class.getDeclaredConstructor(String.class).newInstance("HERESMYARG");

or

obj.getClass().getDeclaredConstructor(String.class).newInstance("HERESMYARG");

myObject.getClass().getDeclaredConstructors(types list).newInstance(args list);

Edit: according to the comments seems like pointing class and method names is not enough for some users. For more info take a look at the documentation for getting constuctor and invoking it.

Assuming you have the following constructor

class MyClass {
    public MyClass(Long l, String s, int i) {

    }
}

You will need to show you intend to use this constructor like so:

Class classToLoad = MyClass.class;
     
Class[] cArg = new Class[3]; //Our constructor has 3 arguments
cArg[0] = Long.class; //First argument is of *object* type Long
cArg[1] = String.class; //Second argument is of *object* type String
cArg[2] = int.class; //Third argument is of *primitive* type int

Long l = new Long(88);
String s = "text";
int i = 5;

classToLoad.getDeclaredConstructor(cArg).newInstance(l, s, i);

Do not use Class.newInstance(); see this thread: Why is Class.newInstance() evil?

Like other answers say, use Constructor.newInstance() instead.

You can get other constructors with http://java.sun.com/javase/6/docs/api/java/lang/Class.html#getConstructor(java.lang.Class...)">getConstructor(...)</a>;.

Follow below steps to call parameterized consturctor.

1. Get Constructor with parameter types by passing types in Class[] for getDeclaredConstructor method of Class
2. Create constructor instance by passing values in Object[] for
   newInstance method of Constructor

Example code:

import java.lang.reflect.*;

class NewInstanceWithReflection{
	public NewInstanceWithReflection(){
		System.out.println("Default constructor");
	}
	public NewInstanceWithReflection( String a){
		System.out.println("Constructor :String => "+a);
	}
	public static void main(String args[]) throws Exception {
		
		NewInstanceWithReflection object = (NewInstanceWithReflection)Class.forName("NewInstanceWithReflection").newInstance();
		Constructor constructor = NewInstanceWithReflection.class.getDeclaredConstructor( new Class[] {String.class});
		NewInstanceWithReflection object1 = (NewInstanceWithReflection)constructor.newInstance(new Object[]{"StackOverFlow"});
		
	}
}

output:

java NewInstanceWithReflection
Default constructor
Constructor :String => StackOverFlow

You can use the getDeclaredConstructor method of Class. It expects an array of classes. Here is a tested and working example:

public static JFrame createJFrame(Class c, String name, Component parentComponent)
{
    try
    {
        JFrame frame = (JFrame)c.getDeclaredConstructor(new Class[] {String.class}).newInstance("name");
        if (parentComponent != null)
        {
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        }
        else
        {
            frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        }
        frame.setLocationRelativeTo(parentComponent);
        frame.pack();
        frame.setVisible(true);
    }
    catch (InstantiationException instantiationException)
    {
        ExceptionHandler.handleException(instantiationException, parentComponent, Language.messages.get(Language.InstantiationExceptionKey), c.getName());
    }
    catch(NoSuchMethodException noSuchMethodException)
    {
        //ExceptionHandler.handleException(noSuchMethodException, parentComponent, Language.NoSuchMethodExceptionKey, "NamedConstructor");
        ExceptionHandler.handleException(noSuchMethodException, parentComponent, Language.messages.get(Language.NoSuchMethodExceptionKey), "(Constructor or a JFrame method)");
    }
    catch (IllegalAccessException illegalAccessException)
    {
        ExceptionHandler.handleException(illegalAccessException, parentComponent, Language.messages.get(Language.IllegalAccessExceptionKey));
    }
    catch (InvocationTargetException invocationTargetException)
    {
        ExceptionHandler.handleException(invocationTargetException, parentComponent, Language.messages.get(Language.InvocationTargetExceptionKey));
    }
    finally
    {
        return null;
    }
}

I think this is exactly what you want http://da2i.univ-lille1.fr/doc/tutorial-java/reflect/object/arg.html

Although it seems a dead thread, someone might find it useful