Getting the class of a primitive type or void

Hello,
Class.forName cannot be used to get the class of a primitive type or void. What does then ???
I thought of defining a class for each primitive type and override getClass() to return the required type, but getClass() is final ...
Please help

I don't understand what you mean e.g.I get the name of the primitive type at runtime and need to convert it to a class. For example, Class.forName("byte") returns byte.class. But, unfortunately, Class.forName() doesn't return classes of primitives or void.
I already solved the problem through putting ptimitive classes in a hashtable. But I was wondering if there is a simpler solution !!!

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Any Java built in function to get the Class type corresponding to primitive

I know it sounds strange but basically I have a Class and a String (I'm reading values from an XML file).
If the Class is a primitive type (boolean, byte, char, short, int, long, float, and double) I would have to convert the String into the corresponding types.
So I know how to do stuff like
Integer.parseInt("22");but for all the primitive types is there some method where I can simply get a way to do that without writing a whole bunch of if statements?

You could set up a class to parse your String. You could check to see if it contains a decimal point, if so then you check to see if it is less than float.MAX_VALUE etc same for the Integer family and you could use equals method to check if it is true or false.
one other way would be to use parseInt etc and catch exceptions if there is an error, this is a bad idea though and a dirty way to do things.
As suggested, maybe you have some idea of what data type your expecting and can limit the amount of parsing you have to do. Another way is to group all numeric values as doubles.
You could start with something like this adding other methods checking the max value of the data types.
public class StringParser
     public static void main(String[] args)
          String test = "1.0";
          System.out.println(containsDecimal(test));
          if (containsDecimal(test))
               decimalSizeFinder(test);
          else
               integerSizeFinder(test);
     static boolean containsDecimal(String input)
          for(int i=0; i<input.length(); i++)
               if (input.charAt(i) =='.')
                    return true;
          return false;
     static void integerSizeFinder(String input)
          long value = Long.parseLong(input);
          if(value <=Byte.MAX_VALUE)
               byte b = (byte)value;
          else if(value <= Short.MAX_VALUE)
               short s = (short)value;
          else if(value <=Integer.MAX_VALUE)
                int i = (int)value;
          //etc
        //Add code to assign the value to a variable someplace
     static void decimalSizeFinder(String input)
          double value = Double.parseDouble(input);
          if(value <=Float.MAX_VALUE)
               float f = (float)value;
       //Add code to assign the value to a variable someplace
}Message was edited by:
kikemelly
Message was edited by:
kikemelly

Create array of arbitrary dimensions / get Class object for primitive types

Here's an interesting problem: is there any way to code for the creation of an n-dimensional array where n is only known at runtime (input by user, etc.)?
java.lang.reflect.Array has a newInstance method which returns an array of an arbitrary number of dimensions specified by the int[] argument, which would give me what I want. However, the other argument is a Class object representing the component type of the array. If you want to use this method to get an array of a primitive type, is it possible to get a Class object representing a primitive type?

That doesn't help, since the whole problem is that the number of dimensions aren't known until runtime. You can't simply declare a variable of type int[][] or use an int[][] cast, since the number of []'s is variable.
The int.class construction was partly what I was looking for. This returns the array needed (assuming some read method):
int dimensions = read();
int size = read();
int[] index = new int[dimensions];
for (int i = 0; i < dimensions; i++)
index[i] = size;
Object myArray = Array.newInstance(int.class, index);The only problem is, as an Object, I can't use myArray usefully as an array. And I can't use a cast, since that requires a fixed number of dimensions.

Get the Class of something i have in mind

i found 2 ways of getting the class of a type
1. return Class.forName("Boolean");
2. static Boolean aBoolean = new Boolean(true);
return aBoolean.getClass();
the first one throws an exception and in the second one i have to create a random object. is there a nicer way to do this?

You have to use the fully qualified class names with Class.forName... for Boolean it is java.lang.Boolean.
Two ways that don't create unnecessary objects:
1. return Class.forName("java.lang.Boolean");
2. return Boolean.class;
and if you wanted the class of the primitive type boolean you can use Boolean.TYPE or boolean.class...

Arrays of arbitrary dimensions / Class object for primitive types

Here's an interesting problem: is there any way to code for the creation of an n-dimensional array where n is only known at runtime (input by user, etc.)?
java.lang.reflect.Array has a newInstance method which returns an array of an arbitrary number of dimensions specified by the int[] argument, which would give me what I want. However, the other argument is a Class object representing the component type of the array. If you want to use this method to get an array of a primitive type, is it possible to get a Class object representing a primitive type?

Devil is in the detailspublic class Test2 {
public static void main(String[] args) {
    Object[] myArray = new Object[10];
    fillDimensionalArray(myArray, 5, 5);
public static void fillDimensionalArray(Object[] array, int dim, int size) {
    if (dim==1) {
      for (int i=0; i<size; i++) {
        array[i] = new int[size];
        for (int j=0; j<size; j++) ((int[])array)[j]=999;
} else {
for (int i=0; i<array.length; i++) {
array[i] = new Object[size];
for (int j=0; j<size; j++) {
fillDimensionalArray( (Object[]) array[i], dim - 1, size);

How is it posible to get the File name, size and type from a File out the H

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%>
BEAN
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Thanks it works great.
Here an excample from my code
import org.apache.commons.fileupload.*;
public class FileUploadBean extends Object implements java.io.Serializable{
String foutmelding = "geen";
String path;
String filename;
public boolean doUpload(HttpServletRequest request) throws IOException
     try
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     upload.setSizeThreshold(100000000);
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Hi Rajeev,
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gloucester
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RajEndiran wrote:
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Hi
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Edited by: 849614 on Aug 11, 2011 6:49 AM

YoungWinston wrote:
maheshguruswamy wrote:
Agreed, but IMO, i still feel its best if there is no tie in between consumer class level details and the database it talks to. A service layer is needed in between them.Sounds like you've done a bit of this before. Me, I've either been a modeller/DBA, doling out data, or a nuts and bolts programmer (and actually more toolmaker than apps, but did a bit of that too).
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Edited by: YoungWinston on Aug 11, 2011 10:34 PM
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[url http://www.amazon.com/Enterprise-Integration-Patterns-Designing-Deploying/dp/0321200683/ref=pd_sim_b_1]Enterprise Integration Patterns

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Getting the class of a primitive type or void

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