Using null for parameterized "newInstance(Object [])" method in Object[].

Question

I have a really serious problem. I am creating instances of specific classes by using reflection techniques. I am reading a flat file, finding class from its name and creating it by using its parameterized constructor. Example:
line 1: Dummy("A",Dummy2("B"),12,,"C");
I create an instance of Dummy with parameters "A", an instance of Dummy2 object with value "B", 12 (I use here Integer as wrapper), null (There is no wrapper for null :( ) and "C".
I find constructor by using findConstructors() and looking their parameter counts, creating an object array with given values and calling:
constructorIFoundBefore.newInstance(objectArrayIPrepared);
But!!!
Because I use null directly, I got this message:
java.lang.IllegalArgumentException: argument type mismatch
     at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
     at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
     at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
     at java.lang.reflect.Constructor.newInstance(Constructor.java:274)
     at reader.parser.ObjectCreator.createObjectFromObjectItem(ObjectCreator.java:192)
     at reader.parser.ObjectCreator.createObjectFromParseItem(ObjectCreator.java:112)
     at reader.parser.ObjectCreator.createObject(ObjectCreator.java:78)
     at reader.analyzer.FileAnalyzer.analyzeAndCreateObjects(FileAnalyzer.java:95)
     at reader.ReverseReader.main(ReverseReader.java:43)
I will be very glad if you help me.
Thanks a lot!
Gokcer

Answer 1

I said something wrong. Sorry. While invoking a method (or a constructor) we need an object array which are equivalent to parameters. For example to call a method or constructor for class A;
class A {
int age;
String name;
public A(int age, String name){
this.age = age;
this.name = name;
public set(int age, String name){
this.age = age;
this.name = name;
we use in any place
A a1 = new A(12,"Gokcer");
A a2 = new A(15,null);
To achieve this by using reflection techniques, we must find constructor with two parameters of class A. At this point "BetterMethodFinder" will give great help.
After finding right constructor, we must create an object array to tell the constructor parameters (age and name). At this point we need an object array which stores our parameters. Code must be like this.
Object []params = new Object[2]; // we have two parameters.
params[0] = new Integer(12); // we can't use params[0]=12
// because 12 is not an object. (It is a
// primitive type)
params[1] = "Gokcer";
Now create the new object.
A a1;
a1 = constructorWeFound.newInstance(params);
While creating param[], we could also use:
Object []params = new Object[2] {new Integer(12),"Gokcer"};
While creating a2, we can use "null" directly for second parameter.
params = new Object[2] = {new Integer(15), null};
or
Object []params = new Object[2];
params[0] = new Integer(15);params[1] = null;
Thanks again everyone who replied me.
My sincerely...