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Translating a string-representation of a function's parameter list to actual parameters, for a reflective call

UPDATE: After getting an unexpected-in-a-good-way answer, I've added some context to the bottom of this question, stating exactly how I'll be using these string-function-calls.
I need to translate a string such as
my.package.ClassName#functionName(1, "a string value", true)
into a reflective call to that function. Getting the package, class, and function name is not a problem. I have started rolling my own solution for parsing the parameter list, and determining the type of each and returning an appropriate object.
(I'm limiting the universe of types to the eight primitives, plus string. null would be considered a string, and commas and double-quotes must be strictly escaped with some simple marker, such as __DBL_QT__, to avoid complications with unescaping and splitting on the comma.)
I am not asking how to do this via string-parsing, as I understand how. It's just a lot of work and I'm hoping there's a solution already out there. Unfortunately it's such generic terminology, I'm getting nowhere with searching.
I understand asking for an external existing library is off topic for SO. I'm just hoping to get some feedback before it's shutdown, or even a suggestion on better search terms. Or perhaps, there is a completely different approach that might be suggested...
Thank you.
Context:
Each function call is found within a function's JavaDoc block, and represents a piece of example code--either its source code or its System.out output--which will be displayed in that spot.
The parameters are for customizing its display, such as
indentation,
eliminating irrelevant parts (like the license-block), and
for JavaDoc-linking the most important functions.
This customization is mostly for the source-code presentation, but may also be applied to its output.
(The first parameter is always an Appendable, which will do the actual outputting.)
The user needs to be be able to call any function, which in many cases will be a private-static function located directly below the JavaDoc-ed function itself.
The application I'm writing will read in the source-code file (the one containing the JavaDoc blocks, in which these string-function-calls exist), and create a duplicate of the *.java file, which will subsequently processed by javadoc.
So for every piece of example code, there will be likely two, and possibly more of these string-function-calls. There may be more, because I may want to show different slices of the same example, in different contexts--perhaps the whole example in the overall class JavaDoc block, and snippets from it in the relevant functions in that class.
I have already written the process that parses the source code (the source code containing the JavaDoc blocks, which is separate from the one that reads the example-code), and re-outputs its source-code blindly with insert example-code here and insert example-code-output here markers.
I'm now at the point where I have this string-function-call in an InsertExampleCode object, in a string-field. Now I need to do as described at the top of this question. Figure out which function they want to invoke, and do so.

Change the # to a dot (.), write a class definition around it so that you have a valid Java source file, include tools.jar in your classpath and invoke com.sun.tools.javac.Main.
Create your own instance of a ClassLoader to load the compiled class, and run it (make it implement a useful interface, such as java.util.concurrent.Callable so that you can get the result of the invocation easily)
That should do the trick.

The class I created for this, called com.github.aliteralmind.codelet.simplesig.SimpleMethodSignature, is a significant piece of Codelet, used to translate the "customizer" portion of each taglet, which is a function that customizes the taglet's output.
(Installation instructions. The only jars that must be in your classpath are codelet and xbnjava.)
Example string signatures, in taglets:
{#.codelet.and.out com.github.aliteralmind.codelet.examples.adder.AdderDemo%eliminateCommentBlocksAndPackageDecl()}
The customizer portion is everything following the percent sign (%). This customizer contains only the function name and empty parameters. This implies that the function must exist in one of a few, strictly-specified, set of classes.
{#.codelet.and.out com.github.aliteralmind.codelet.examples.adder.AdderDemo%lineRange(1, false, "Adder adder", 2, false, "println(adder.getSum())", "^ ")}
This specifies parameters as well, which are, by design, "simple"--either non-null strings, or a primitive type.
{#.codelet.and.out com.github.aliteralmind.codelet.examples.adder.AdderDemo%com.github.aliteralmind.codelet.examples.LineRangeWithLinksCompact#adderDemo_lineSnippetWithLinks()}
Specifies the explicit package and class in which the function exists.
Because of the nature of these taglets and how the string-signatures are implemented, I decided to stick with direct string parsing instead of dynamic compilation.
Two example uses of SimpleMethodSignature:
In this first example, the full signature (the package, class, and function name, including all its parameters) are specified in the string.
import com.github.aliteralmind.codelet.simplesig.SimpleMethodSignature;
import com.github.xbn.lang.reflect.InvokeMethodWithRtx;
import java.lang.reflect.Method;
public class SimpleMethodSigNoDefaults {
public static final void main(String[] ignored) {
String strSig = "com.github.aliteralmind.codelet.examples.simplesig." +
"SimpleMethodSigNoDefaults#getStringForBoolInt(false, 3)";
SimpleMethodSignature simpleSig = null;
try {
simpleSig = SimpleMethodSignature.newFromStringAndDefaults(
String.class, strSig, null, null,
null); //debug (on=System.out, off=null)
} catch(ClassNotFoundException cnfx) {
throw new RuntimeException(cnfx);
}
Method m = null;
try {
m = simpleSig.getMethod();
} catch(NoSuchMethodException nsmx) {
throw new RuntimeException(nsmx);
}
m.setAccessible(true);
Object returnValue = new InvokeMethodWithRtx(m).sstatic().
parameters(simpleSig.getParamValueObjectList().toArray()).invokeGetReturnValue();
System.out.println(returnValue);
}
public static final String getStringForBoolInt(Boolean b, Integer i) {
return "b=" + b + ", i=" + i;
}
}
Output:
b=false, i=3
This second example demonstrates a string signature in which the (package and) class name are not specified. The potential classes, one in which the function must exist, are provided directly.
import com.github.aliteralmind.codelet.simplesig.SimpleMethodSignature;
import com.github.xbn.lang.reflect.InvokeMethodWithRtx;
import java.lang.reflect.Method;
public class SimpleMethodSigWithClassDefaults {
public static final void main(String[] ignored) {
String strSig = "getStringForBoolInt(false, 3)";
SimpleMethodSignature simpleSig = null;
try {
simpleSig = SimpleMethodSignature.newFromStringAndDefaults(
String.class, strSig, null,
new Class[]{Object.class, SimpleMethodSigWithClassDefaults.class, SimpleMethodSignature.class},
null); //debug (on=System.out, off=null)
} catch(ClassNotFoundException cnfx) {
throw new RuntimeException(cnfx);
}
Method m = null;
try {
m = simpleSig.getMethod();
} catch(NoSuchMethodException nsmx) {
throw new RuntimeException(nsmx);
}
m.setAccessible(true);
Object returnValue = new InvokeMethodWithRtx(m).sstatic().
parameters(simpleSig.getParamValueObjectList().toArray()).invokeGetReturnValue();
System.out.println(returnValue);
}
public static final String getStringForBoolInt(Boolean b, Integer i) {
return "b=" + b + ", i=" + i;
}
}
Output:
b=false, i=3

java 6 ArrayLists and Arrays and Generics

I have a varargs method and I want to call the method using 1 or 0 arguments.
The following code compiles, but does not run correctly:
final List<MyMessage> allMessages = new ArrayList<MyMessage>();
MyMessage message = null;
if (checkSomeCondition()) {
message = new MyMessage(someParam);
allMessages.add(message);
}
int size = allMessages.size();
MyMessage[] msgArrayType = new MyMessage[size]; // ERROR
MyMessage[] msgArray = allMessages.toArray(msgArrayType);
callFunc(msgArray);
...........
public void callFunc(MyMessage... messages) {
}
When I debug the code, after the line that I marked with //ERROR, the value of the array msgArrayType is com.sun.jdi.ClassNotLoadedException: Type has not been loaded occurred while retrieving component type of array.
This is also wrong:
MyMessage[] msgArray = (MyMessage[]) allMessages.toArray();
// -> java.lang.Object cannot be cast to .......MyMessage
I really don't understand it, because allMessages is a List of MyMessages!
The only option I see is to use something like
if (message == null) {
callFunc();
} else {
callFunc(message);
}
but I was wondering how the code would look like if I want to write callFunc only once. Any suggestions?

If you want to use varargs, which excepts an array - you should also make sure that the elements passed are non null.
So if you just want to use one function call of callfunc() and don't want to surround with if-else block you can use the following function call.
callfunc(message == null ? (Object)null : message);
This will either pass in the message object wrapped in array, or it will pass an array with single null element.

Using User input for the reflection process in java

basically am trying to make java command prompt. Suppose user enters as input from the user:
new x java.util.ArrayList
here x is the object name and java.util.ArrayList is the class. So this script inputed by the user means create an object of class java.util.ArrayList.
Now suppose that user enter:
new x java.util.ArrayList int:5
means create an object x of the java.util.ArrayList and make its size 5. Like this i want that everytime i input something related to object creation as input i should be able to create class its object and its method based on the input that the user does. Am new to java and reflection so kindly help! here is the code i thought so far using my mind:
public static void token_classification() throws ClassNotFoundException
{
my_hash = new HashMap();
Keep_Obj_Info = new HashMap();
if(expression_keeper[0].equalsIgnoreCase("new"))
{
my_hash.put("Object", expression_keeper[1]);
Class Obj= Class.forName(expression_keeper[2]);
Keep_Obj_Info.put("Modifier", Obj.getModifiers());
Keep_Obj_Info.put("Package",Obj.getPackage());
////????
Constructor[] constructors = Obj.getConstructors();
}
else
if(expression_keeper[0].equalsIgnoreCase("call"))
{
}
else
if(expression_keeper[0].equalsIgnoreCase("print"))
{
}
else
{
System.out.println("Invalid Script!");
}
}
ExpressionKeeper is basically a String array that keeps the user input in tokenized form. Meaning anything next to a white space to a new location.

Well for Object creation in java; the constructor and it's arguments are required.
you can have a generic framework which will accept input from command prompt and interpret them means find out the data type of the input ex : number/string/char/boolean etc..
Also your framework should know the argument index for example say a constructor has 2 parameter and one is string and another is int. and say first parameter is int and 2nd parameter is String and while passing the parameter from the command line the user first pass string and then int in that scenario your program should be smart enough to properly arrange them in order. So many such things you need to take care of....Now coming to the example which you have mentioned for ArrayList you can write a program as follows : (I have just given you a pseudocode you can implement your own way)
{
int howManyParametersFromCommandLine = getnoParameterCount; //it will maintain no.of parameters passed from command line
String[] parametersFromCommandLine = getParametersFromcommandLine(); // Ex : {1,"ABC",new Double(80.0d)};
List<Class> parameterTypesList = parseParameters(parametersFromCommandLine); //This will identify type of each of the parameter
Class clazz = Class.forName("youClassName");
Constructor[] cons = clazz.getConstructors();
for(Constructor c : cons)
{
Class[] parameterTypes = c.getParameterTypes();
if(parameterTypes.length == howManyParametersFromCommandLine)
{
//try to match the parameter type in parameterTypesList with parameterTypes if this matches then
boolean typeMatchingAndSequecneSucess = matchParameters(parameterTypes,parameterTypesList);
if(typeMatchingAndSequecneSucess)
{
if(c.isAccessible())
{
Object[] initargs = parseAndRetActualParamValue(parametersFromCommandLine);
return c.newInstance(initargs);
}
}
}
}
}
Hope this will help you !!

You may want to use the Interpreter design pattern. It is used just for that.
The Interpreter is a bit complex, but will ensure you code interpretation works right. Also, it gives you a easy inclusion of new commands.
Take a look at here: http://en.wikipedia.org/wiki/Interpreter_pattern
Hope I could help.

Nightmare Class - floats/strings

This is my class reponsible for new item entries, and from the start it has been a complete nightmare, I can't seem to resolve the issues I am facing which are:
setStock(float) in Item cannot be applied to ()
Item entry:
private void writeItemRecord()
{
// Check to see if we can connect to database table
if ( DataBaseHandler.makeConnectionToitemDB() == -1)
{
JOptionPane.showMessageDialog (frame, "Unable to connect to database table (Item)");
}
else // Ok, so first read data from the text fields
{
// Read data from form and store data
String Itemname = ItemnameTxtField.getText();
String Itemcode = ItemcodeTxtField.getText();
String Description = DescriptionTxtField.getText();
String Unitprice = UnitpriceTxtField.getText();
String Style = StyleTxtField.getText();
String Finish = FinishTxtField.getText();
String Stock = StockTxtField.getText();
// Convert priceStr to a float
Float fvar = Float.valueOf(Unitprice);
float price = fvar.floatValue();
Float svar = Float.valueOf(Stock);
float stock = svar.floatValue();
// Create a Item oject
Item Item = new Item();
// Set the attributes for the Item object
Item.setItemname (Itemname);
Item.setItemcode (Itemcode);
Item.setDescription (Description);
Item.setUnitprice (price);
Item.setStock(stock);
Item.setStyle(Style);
Item.setFinish(Finish);
// Write Item record. Method writeToItemTable() returns
// 0 of OK writing record, -1 if there is a problem. I store
// the returned value in a variable called error.
int error = DataBaseHandler.writeToItemTable(Item.getItemname(),
Item.getItemcode(),
Item.getDescription(),
Item.getUnitprice(),
Item.setStock(),
Item.setStyle(Style),
Item.setFinish(Finish),
Item.setSuppliercode(Suppliercode),
Item.setSuppliername(Suppliername),
Item.setAddress(Address)
);
// Check if there is a problem writing the record, in
// which case error will contain -1
if (error == -1)
{
JOptionPane.showMessageDialog (frame, "Problem writing record to Item Table");
}
// Clear the form - actual method is coded below
clearForm();
// Close database connection. Report an error message
// if there is a problem.
if ( DataBaseHandler.closeConnection() == -1 )
{
JOptionPane.showMessageDialog (frame, "Problem closing data base conection");
}
}
} // End
Any help is much appreciated!
And item extracts:
public void setStock(float StockIn)
{
Stock = StockIn;
}
public float getStock()
{
return Stock;
}

For starters, adhere to Java naming conventions. Nothing except class/interface names is allowed to use CamelCase. Use lowerCamelCase. As for your "problem", you wrote
Item.setStock(),
so obviously it's giving you the error. It is also giving you the exact line number of the error, something that would obviously have helped us to diagnose your problem.
Solution: use Item.getStock() (i suppose, it's hard to tell). Calling Item.setStock at that position (as an argument to a method call) is meaningless anyway, given that setStock is a void method.

Java compiler errors come with a line number - pay attention to it. This is your problem:
Item.setStock()
setStock() requires a parameter, you are trying to call it without one. Perhaps you meant getStock()? And I suspect that all the calls to set methods in the parameter list to writeToItemTable are also wrong, as those set methods will have void as return value, so you can't use them that way.

The setStock method looks like this:
public void setStock(float StockIn)
To call it, you need to pass a float as an argument. Somewhere in your code, you call the method, like this:
Item.setStock(),
The method needs to be called with the float argument, but instead it's called with none, hence you see a compilation error.

In this code:
int error = DataBaseHandler.writeToItemTable(Item.getItemname(),
Item.getItemcode(),
Item.getDescription(),
Item.getUnitprice(),
// Right here --> Item.setStock(),
Item.setStyle(Style),
Item.setFinish(Finish),
Item.setSuppliercode(Suppliercode),
Item.setSuppliername(Suppliername),
Item.setAddress(Address)
);
Notice that you're calling Item.setStock(), Item.setStyle(Style), etc. instead of Item.getStock(), Item.getStyle(), etc. This is probably the source of your problem - you're trying to call the setStock() method with no arguments, hence the error.
Hope this helps!

This line
// Create a Item oject
Item Item = new Item();
Is problematic. Not only is it bad style in Java to use uppercase names for variables, this particular instance results in a compile error. Also, you're calling setStock without a parameter. You need to fix that as well.

Here is your error:
int error = DataBaseHandler.writeToItemTable(Item.getItemname(),
Item.getItemcode(),
Item.getDescription(),
Item.getUnitprice(),
Item.setStock(), // <<< here! should be getStock()
Item.setStyle(Style),
Item.setFinish(Finish),
Item.setSuppliercode(Suppliercode),
Item.setSuppliername(Suppliername),
Item.setAddress(Address));
But again... consider naming/coding conventions.

Java: ExceptionInInitializerError caused by NullPointerException when constructing a Locale object

I'm working on localization for a program I've written with a couple other guys. Most of the strings now load in the appropriate language from an ini file. I'm trying to do the same with the format of currency in the program. However, I'm getting a runtime exception as soon as I attempt to launch the application.
I'm using the Locale object as a parameter to a few NumberFormat.getCurrencyInstance()'s, like so:
private static final NumberFormat decf;
static
{
decf = NumberFormat.getCurrencyInstance(Lang.cLocale);
decf.setRoundingMode(RoundingMode.HALF_UP);
}
Lang is the class which contains all the localization stuff. The code the IDE complains about at attempted runtime is public static Locale cLocale = new Locale(GUI.DB_info[19],GUI.DB_info[20]);
GUI is the class the GUI is contained in, and where we decided to construct the DB_info array (which itself just contains information loaded from a remote database in another class). DB_info[19] is the language code (es right now) and DB_info[20] is the country code (US). The array elements are being properly filled-- or were, I can't get far enough into the program to tell right now; but nothing has changed with the code for filling DB_info.
The full exception is as follows:
Exception in thread "main" java.lang.ExceptionInInitializerError
at greetingCard.GUI.<clinit>(GUI.java:118)
Caused by: java.lang.NullPointerException
at java.util.Locale.<init>(Unknown Source)
at java.util.Locale.<init>(Unknown Source)
at greetingCard.Lang.<clinit>(Lang.java:13)
... 1 more
The line in GUI referenced is: static String welcome = Lang.L_WELCOME + ", " + empName;, and Lang.java basically looks like this:
// Set locale for currency display
public static Locale cLocale = new Locale(GUI.DB_info[19],GUI.DB_info[20]); // language, country
// Employee specific strings
public static String L_AMT_REMAIN = "";
public static String L_AMT_TEND = "";
public static String L_APPROVED = "";
public static String L_ARE_YOU_SURE = "";
[...]
public static void Main(String emp_lang)
{
String header = "";
if (emp_lang.equals("ENG"))
{
header = "ENG";
}
else if (emp_lang.equals("SPA"))
{
header = "SPA";
}
else if (emp_lang.equals("FRE"))
{
header = "FRE";
}
else if (emp_lang.equals("GER"))
{
header = "GER";
}
else
{
header = "ENG";
}
try
{
Ini ini = new Ini(new File("C:/lang.ini"));
L_AMT_REMAIN = ini.get(header, "L_AMT_REMAIN");
L_AMT_TEND = ini.get(header, "L_AMT_TEND");
L_APPROVED = ini.get(header, "L_APPROVED");
L_ARE_YOU_SURE = ini.get(header, "L_ARE_YOU_SURE");
[...]
L_WELCOME = ini.get(header, "L_WELCOME");
L_WELCOME2 = ini.get(header, "L_WELCOME2");
L_XACT_CHNG = ini.get(header, "L_XACT_CHNG");
L_YES = ini.get(header, "L_YES");
System.err.println("Employee Language: " + header);
}
catch (InvalidFileFormatException e)
{
e.printStackTrace();
}
catch (IOException e)
{
e.printStackTrace();
}
} // end public static void main
That's for the majority of the strings to be displayed in different languages. There is another method inside Lang that loads some other strings, independent of the first set. I don't believe it factors into this problem but I can post it if needed.
The order in which these classes/methods get launched is as follows:
GUI.Main calls the Login class, which calls a CreateLogin method. That method calls Clients.main, which gets the DB_info array from GUI passed to it. Clients fills the DB_info array. Lang.other is then called (to get language-specific strings for the login page), and the Login buttons and labels are created. Once a login is successful, the perferred language of the employee logging in (from a DB) is passed to Lang.main to load the other strings (hence the emp_lang being passed in the code above).
Up until I added the code for the Locale object, all of this worked fine. Now I get the ExceptionInInitializerError exception. Anyone know what's going on?
BTW, for loading from the ini file I'm using ini4j. Some forum posts I found while googling suggest this is a problem with that, but I don't see how it relates to the problem with Locale objects. The ini stuff works (worked) fine.

Sounds like you have a cycle in your static initializers, so something is not initialized yet.
GUI calls Lang's static initializer before getting Lang.L_WELCOME. Lang calls GUIs static initializer in line 2. Your exception trace makes it look like GUI calls Langs static initializer for some reason.
In all, cycles like this mean that someone is going to reference a statically initialized object and get null instead of what they expected to get. In this case, I suspect Lang.java, line 2, is passing two null pointers to the Locale constructor.

As Keith notes, you have a static initializer cycle. To help future readers...
To minimize these bugs, initialize (simple) constants (with no or minimal constructors) before (complex) variables, so here String before Locale – less room for cycles to cause problems.
Debugging-wise, NullPointerException on a static field and 2 <clinit> in stack trace, with the earlier class appearing in the failing line, are the clues that this is an uninitialized field caused by a static initializer cycle.