Using Java Reflection to invoke a method with Array Parameters

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Invoking a method that accepts array parameters using java reflection is a little bit tricky. The following code shows how to do it the right way and the possible errors you may see if you get it wrong.

–Class with a method that accepts an array —

public class Dao {

public void Method2(String[] params){

//do something

}

}

— Test Class With CORRECT CODE–

public class Test {

public static void main(String[] args) throws Exception{
Class classToCall = Class.forName(“Dao”);
String[] argu ={“1″,”2”};
Method methodToExecute = classToCall.getDeclaredMethod(“Method2”, new Class[]{String[].class});
methodToExecute.invoke(classToCall.newInstance(), new Object[]{argu});

}

}

— Test Class WITH CODE that gives java.lang.IllegalArgumentException: wrong number of arguments—

public class Test {

public static void main(String[] args) throws Exception{
Class classToCall = Class.forName(“Dao”);
String[] argu ={“1″,”2”};
Method methodToExecute = classToCall.getDeclaredMethod(“Method2”, new Class[]{String[].class});
methodToExecute.invoke(classToCall.newInstance(), argu);

}

}

— Test Class WITH CODE that gives java.lang.IllegalArgumentException: argument type mismatch—

public class Test {

public static void main(String[] args) throws Exception{
Class classToCall = Class.forName(“Dao”);
String[] argu ={“1”};
Method methodToExecute = classToCall.getDeclaredMethod(“Method2”, new Class[]{String[].class});
methodToExecute.invoke(classToCall.newInstance(), argu);

}

}