Java primitive types??

What r the Java primitive types??What is it for?

What exam or job interview are you studying for exactly? One day it's strange questions on EJB, an another JSF, on another some question about Servlets demonstrating a lack of fundamental understanding of web services and today primitives?
Please give due consideration to actually learning Java properly and not just random bits and pieces. Your current style is not working for you as can be seen from the constant utter confusion of many of your questions and posts.

Similar Messages

Configure array of primitive type for POF

My impression is that Coherence's POF implementation can handle Java primitive and String by default thus we don't need to provide a customized POF configuration file if the object been put into the cache is Java primitive type.
How about arrary of primitive type? For example, byte[]. Can Coherence's POF implementation handle byte[] as well?

Just asking since we plan to move from using Externalizable to POF and not sure if we need special handling for byte[] type.
Thanks for the reply.
Regards,
Chen

Reference to primitive types?

I want to write a GUI that is able to set parameters to classes without knowing the exact nature of parameters. The parameter types are restricted to int and String. Something like this:
...in GUI class:
ClassToConfigure c = getFromSomewhere();
for (int i=0; i<c.getPropertyCount(); i++) {
addToGUI(c.getDescription(), c.getType(), c.getKeyName())
then later after the value is set in the GUI:
c.setProperty(keyName, newValue);the setProperty method would have implementations for each type of newValue, and the GUI would have editing capabilities for each type too.
My problem is that I do not know how to implement this in the ClassToConfigure (CTC). My thoughts were: CTC enumerates all field it wants to be configurable in its constructor, something like:
addProperty(actual_field, "int", "Some description", "UniqueName");the CTC class would have a list of all properties with the "references" to the actual field to be able to update them.
but then I don't know how to update the fields when CTC.setProperty() is called. Is there a way to keep a reference to a field, even if the field has a primitive type? Another way to do it would be using function pointers, passing the getter and setter to CTC.addProperty, but this isn't possible in java.
Is there any straightforward way of implementing such behavior in java without tricky use of reflection?
Thanks in advance,
-Lev
P.S. I hope I made my point understandable, if not please let me know and I'll try to rephrase my concern.

I did not understand what you meant. But you can have the OO equivalents to function pointers, and that is method references. (But that is part of the the java.lang.reflect package)
Kaj

Need suggestion for variable size array of primitive type.

Hi all,
I am working on a problem in which I need to keep an array of primitive (type int) sorted. Also I insert new elements while keeping it sorted, and at times I merge two similar arrays with unique elements.
I would welcome suggestions on the implementation aspects as to which type/class to use. My primary consideration is performance. Here are my observations:
1. type int
Efficient operation, but arrays are fixed size so it makes clumsy code and overhead when the array is expanded or merged with another.
Methods in class Arrays can be used, incl. binary search and sort.
2. Vector, ArrayList, List, LinkedList
Accept objects only. I can use Integer instead of int, but it will involve overhead, and I'll need to write my own sort and search routines (already done).
For now, I choose option 2 using Vectors. Is there a better choice, or are there other options, given the conditions and consideration enumerated at the beginning?
Appreciate any input or comments.

mathmate wrote:
I have not had the occasion to use them in parallel to recognize the difference. It pays to talk to people!A small benchmark is easily constructed:
import bak.pcj.list.IntArrayList;
import java.util.Random;
import java.util.ArrayList;
public class CollectionTest {
    static void testObjectsList(ArrayList<Integer> list, int n, long seed) {
        long start = System.currentTimeMillis();
        Random rand = new Random(seed);
        for(int i = 0; i < n; i++)
            list.add(new Integer(rand.nextInt()));
        for(int i = 0; i < n/2; i++)
            list.remove(rand.nextInt(list.size()));
        long end = System.currentTimeMillis();
        System.out.println("objectsList -> "+(end-start)+" ms.");
    static void testPrimitiveList(IntArrayList list, int n, long seed) {
        long start = System.currentTimeMillis();
        Random rand = new Random(seed);
        for(int i = 0; i < n; i++)
            list.add(rand.nextInt());
        for(int i = 0; i < n/2; i++)
            list.remove(rand.nextInt(list.size()));
        long end = System.currentTimeMillis();
        System.out.println("primitiveList -> "+(end-start)+" ms.");
    public static void main(String[] args) {
        long seed = System.currentTimeMillis();
        int numTests = 100000;
        testObjectsList(new ArrayList<Integer>(), numTests, seed);
        testPrimitiveList(new IntArrayList(), numTests, seed);
}In the test above, Java's ArrayList is about 5 times faster. But when commenting out the remove(...) methods, the primitive 3rd party IntArrayList is about 4 to 5 times faster.
Give it a spin.
Again: just try to do it with the standard classes: if performance lacks, look at something else.

Array Of Primitive Type (kodo3.4)

Hello,
I want to map an array of primitive type (double[] or double[][] or...) to
a blob, so I specified the mapping this way:
<extension vendor-name="kodo" key="jdbc-field-map-name" value="blob">
<extension vendor-name="kodo" key="column" value="DATA"/>
</extension>
As I use MySQL and not to have an exception, I have added:
kodo.jdbc.DBDictionary: DriverDeserializesBlobs=false
But when I tried to refresh using kodo.jdbc.meta.MappingTool, I get:
[refresh] Exception in thread "main" kodo.util.FatalInternalException:
Cannot map "fr.ifp.reservoir.model.business.geostat.Lithotype.facies".
Check the class and make sure you are using only supported types.
[refresh] at
kodo.jdbc.meta.DynamicMappingProvider.createFieldMapping(DynamicMappingProvider.java:336)
[refresh] at
kodo.jdbc.meta.DynamicMappingProvider.getFieldMapping(DynamicMappingProvider.java:118)
[refresh] at
kodo.jdbc.meta.MappingRepository.getFieldMapping(MappingRepository.java:470)
[refresh] at
kodo.jdbc.meta.AbstractClassMapping.getFieldMapping(AbstractClassMapping.java:993)
[refresh] at
kodo.jdbc.meta.AbstractClassMapping.getFieldMapping(AbstractClassMapping.java:973)
[refresh] at
kodo.jdbc.meta.AbstractClassMapping.getMappings(AbstractClassMapping.java:939)
[refresh] at
kodo.jdbc.meta.AbstractClassMapping.getDeclaredFieldMappings(AbstractClassMapping.java:659)
[refresh] at
kodo.jdbc.meta.AbstractClassMapping.resolve(AbstractClassMapping.java:801)
[refresh] at
kodo.jdbc.meta.BaseClassMapping.resolve(BaseClassMapping.java:341)
[refresh] at
kodo.jdbc.meta.MappingRepository.resolve(MappingRepository.java:431)
[refresh] at
kodo.jdbc.meta.MappingRepository.getMapping(MappingRepository.java:349)
[refresh] at
kodo.jdbc.meta.MappingRepository.getMapping(MappingRepository.java:177)
[refresh] at kodo.jdbc.meta.MappingTool.refresh(MappingTool.java:591)
[refresh] at kodo.jdbc.meta.MappingTool.run(MappingTool.java:941)
[refresh] at kodo.jdbc.meta.MappingTool.run(MappingTool.java:879)
[refresh] at kodo.jdbc.meta.MappingTool.main(MappingTool.java:802)
Thanks for your help.
nicolas

Hi,
No more succes with persistence-modifier="persistent"...
My class:
public class ArrayWrapper {
private String name;
private double[] array;
public ArrayWrapper(String name, double[] array) {
this.name = name;
this.array = array;
public double[] getValues() {
return array;
public String getName() {
return name;
My metadata file:
<jdo>
<package name="model">
<class name="ArrayWrapper">
<field name="array" persistence-modifier="persistent">
<extension vendor-name="kodo" key="jdbc-field-map-name" value="blob">
<extension vendor-name="kodo" key="column" value="DATA"/>
</extension>
</field>
</class>
</package>
</jdo>
My StackTrace:
refresh-mapping:
[java] Exception in thread "main" kodo.util.FatalInternalException:
Cannot map "model.ArrayWrapper.array". Check the class and make sure you
are using only supported types.
[java] at
kodo.jdbc.meta.DynamicMappingProvider.createFieldMapping(DynamicMappingProvider.java:336)
[java] at
kodo.jdbc.meta.DynamicMappingProvider.getFieldMapping(DynamicMappingProvider.java:118)
[java] at
kodo.jdbc.meta.MappingRepository.getFieldMapping(MappingRepository.java:470)
[java] at
kodo.jdbc.meta.AbstractClassMapping.getFieldMapping(AbstractClassMapping.java:993)
[java] at
kodo.jdbc.meta.AbstractClassMapping.getFieldMapping(AbstractClassMapping.java:973)
[java] at
kodo.jdbc.meta.AbstractClassMapping.getMappings(AbstractClassMapping.java:939)
[java] at
kodo.jdbc.meta.AbstractClassMapping.getDeclaredFieldMappings(AbstractClassMapping.java:659)
[java] at
kodo.jdbc.meta.AbstractClassMapping.resolve(AbstractClassMapping.java:801)
[java] at
kodo.jdbc.meta.BaseClassMapping.resolve(BaseClassMapping.java:341)
[java] at
kodo.jdbc.meta.MappingRepository.resolve(MappingRepository.java:431)
[java] at
kodo.jdbc.meta.MappingRepository.getMapping(MappingRepository.java:349)
[java] at
kodo.jdbc.meta.MappingRepository.getMapping(MappingRepository.java:177)
[java] at kodo.jdbc.meta.MappingTool.refresh(MappingTool.java:591)
[java] at kodo.jdbc.meta.MappingTool.run(MappingTool.java:941)
[java] at kodo.jdbc.meta.MappingTool.run(MappingTool.java:879)
[java] at kodo.jdbc.meta.MappingTool.main(MappingTool.java:802)

Primitive type Changing???

One of my friends sent me this e-mail. Can anyone help??
ok wood, here's one for you:
the software i'm writing get's data from one of two processors on a
satelite. these processors use different #'s of bytes for their
primitive types.
bool - 1 byte
short - 2 bytes
int - 2 bytes
long - 4 bytes
float - 4 bytes.
so..as you know the jvm uses 4 bytes for an int, 8 for a long. I
want to be able to have people who are developing sims ontop of my
framework be able to use a primitiave type, such as an int, and have
it only be 2 bytes...now i'm pretty sure this isn't possible. You
can't overload a primitive type in java right? I have some ideas
here on what to do (create whole new objects, holding byte arrays and
use java.nio to manaage them), but it just seems like such a hastel.
i guess i was wondering if you have ever seen this kindof thing
before and if you had any advice. thanks man.

In C, primitive types can vary in size, based on the platform being used. In Java, the size of primitives is static. If he wants 16-bit storage, short is the way to go. Well, a char is a couple of bytes, too, but it's unsigned, intended for Unicode characters, and probably not what he's looking for anyway...
:o)

BUG code insight declaration insert imports primitive types

Facing this in JDEV 11g 11.1.1.3, studio edition install, bundled jdk1.6.0_18, JDEVADF_11.1.1.3.PS2_GENERIC_100408.2356.5660
When using the 'Declaration Insert' code insight feature for method calls returning primitive arrays, JDev will add an import for the primitive return type. Using CTRL-ALT-V to do the same manually works correctly.
Steps to replicate:
- create a new class with a main method
- inside main method type this code:
"hello".
- the code insight window will appear automatically (if using default code insight settings). Press "CTRL-Space" to access "Declaration Insert".
- start typing "toCharArray", JDev will zero in on the toCharArray method which returns a char[], once selected, press enter to choose it.
- jdeveloper generates the following code:
char[] array = "hello".toCharArray();
which is correct, but also adds an import statement in the beginning of the class:
import char;
which does not compile.
- same behavior can be replicated with code like:
new BigInteger("1").toByteArray();
following the same pattern as above.

although this post is way old it could do with a decent answer.
some guidance can be taken from JSR26: UML Mapping for EJB
find it a www.jcp.org
also this research paper on consistency of reverse engineering between uml tools
http://citeseer.nj.nec.com/545406.html
Where Association is identified by looking at the types of all variables belonging >to a class (excluding method variables etc) and if the type of the variable is >non-primitive, than I have deduced it is an association relationship with that >class.
Would this be the right approach?Yes. You could also say that if it is a java.* type then it would also be an attribute.
Secondly I have noticed in JBuilder, it models dependency relationships by getting >all the Imports at the top of the java source file, is this right?? also I have >read that a dependency can be modelled by the variable types in operation >arguments (paremeterS ?)..JBuilder would be consistent with JSR26, and that's how i intend to implement in ArgoUml.
I would also appreciate if someone could clarify the difference betweeen >Composition and Aggregation for me and explain if it is possible to identify the >two relationships directly from java source code..Composition is a stronger form of ownership. the composed class is owned only by 1 class. Its lifetime is strongly linked to its owner - ie. it is not created before its owner and it is destroyed before its owner is.
eg. leg of a table.
Agregation is weak ownership. the owned class may be owned by several classes.
eg. a company is owned by many shareholders.
Last but not least, what about multiplicity ? am I right in thinking that an >instance variable is 0-1, an array declaration is seen as 0-n (fixed number) and a >Vector/ data collection.. is seen as 0 - * (any number)..sound right.
Alex

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.

To get Class object representing the primitive type by a String

for classes,I can use
classNameString = "java.lang.String"
Class c=Class.forName(classNameString);
to get Class object representing the classNameString.
but to get Class object representing the primitive type ,I have to use something like :
Class c=Integer.TYPE;
is there any way to get Class object representing the primitive type by a String?

not using Class.forName(). you'll just need to key off the String passed to see whether it names a primitive:class ClassUtilities {
   * Gives the <code>Class</code> corresponding to a named class or primitive.
   * @param name FQN of a class, or the name of a primitive type
   * @param loader a {@link java.lang.ClassLoader ClassLoader}
   * @return the <code>Class</code> for the name given. This method
   * converts primitive type names to their particular <code>Class</code>
   * object. <code>null</code>, the empty string, <code>"null"</code>, and
   * <code>"void"</code> yield {@link java.lang.Void#TYPE Void.TYPE}. If any
   * classes require loading because of this operation, the given
   * <code>ClassLoader</code> performs the loading. Such classes are not
   * initialized, however.
   * @throws ClassNotFoundException if the name names an unknown class
   * or primitive
   * @see java.lang.Class#getName
static Class classForNameOrPrimitive( String name, ClassLoader loader )
    throws ClassNotFoundException {
    if ( name == null || name.equals( "" ) || name.equals( "null" ) || name.equals( "void" ) ) {
      return Void.TYPE;
    if ( name.equals( "boolean" ) )
      return Boolean.TYPE;
    if ( name.equals( "byte" ) )
      return Byte.TYPE;
    if ( name.equals( "char" ) )
      return Character.TYPE;
    if ( name.equals( "double" ) )
      return Double.TYPE;
    if ( name.equals( "float" ) )
      return Float.TYPE;
    if ( name.equals( "int" ) )
      return Integer.TYPE;
    if ( name.equals( "long" ) )
      return Long.TYPE;
    if ( name.equals( "short" ) )
      return Short.TYPE;
    return Class.forName( name, false, loader );
}

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);

Axis webservice, wsdl and primitif type

Environnement :
JDK1.6, axis2-1.3, tomcat-6
i have a POJO service called ProjectService wich return a ProjectVO value object, this object contains an item "themeId" of type Long (object not primitif type), because this item can be null.
I use the eclipse wizard (bottom-up methode) to generate the Webservice, i ended with "server side" code, and "client side" code (stub.....) the stub obtained is called ProjectServiceStub wich contains an inner class ProjectVO, but this time
the getThemeId() return a long primitif type and not a Long object.
in the other side the eclipse-axis wizard generate a wsdl, the piece of information regarding themeId, is as follwoing
<xs:element minOccurs="0" name="themeId" nillable="true" type="xs:long"/>
...the probleme is, when the POJO service return a NULL for the themeId item, the Webservice return a negatif big number, because int the ProjectServiceStub.ProjectVO object, the themeId is long and not Long.
how can i fixe this probleme
thanks for your help

That wasnt really the question.
Obviously Ive read the tutorial.
Built my own DII client and webservice.
Now im asking questions not covered by the tutorial.
The question was how to reference complex java types.
What are all the different types that can be included in a WSDL document. So far ive used String, Boolean. what else. Surely there must be a document that points these out!
The answer to the other part of the question was quite simple.
In the WSDL document, if a method takes multiple input paramters, the WSDL lists them by number.
ie string 1, string 2 ect. as shown in previous listing.
call.addParameter("String_1", QNAME_TYPE_STRING,
ParameterMode.IN);
So here you just add the additional parameters changing string 1 for the required parameter.

Java Step Types with Java Virtual Machine higher than java-6u16?

Documentation of Java steps says, that these steps are tested with java version 6 update 16. I am talking about the java step types that can be found in directory <TestStand Public>\TestStand 2010\Examples\Java.
If I install another java version, e. g. java 7, step "Start JVM" will exit with an error "-4" and error message "Could not launch JVM.". While Debugging source code of JavaCall.dll, I figured the failing code line out:
"fpCreateJVM(&jvm,(void**)&env,&vm_args);" is the execution of function "JNI_CreateJavaVM" and returns error code -4.
Till now I could not find out, why the jvm does not start. I guess -4 means "Insufficient memory to create the JVM." (http://zone.ni.com/reference/en-XX/help/370052J-01/tssuppref/infotopics/java_steps_errors/)
Has anyone an advice for me?

This post gave me a hint: http://stackoverflow.com/questions/3400292/jni-enomem-from-jni-createjavavm-when-calling-dll-that-us...
Though my development computer has enough ram, jvm is started within the Teststand process which offers limited memory. I changed JavaCall.c and added parameter "-Xmx64m" to the jvm creation call. Now it works with jre 7.
Because memory space Teststand offers to the jvm is different on different computers, an implementation would be nice that checks how much memory is available and then passes the calculated <MEM> as parameter "-Xmx<MEM>m". Here is an example implementation: https://forums.oracle.com/forums/thread.jspa?threadID=1546540

Java.sql.types and oracletypes

There appear to be difference in the way the constants are mapped in java.sql.types vs oracletypes(). For example date is '91' in oracletypes and '93' in java.sql.types. The DatabaseMetaData.getColumns() function reports data_type as a java.sql.type. Is there any mapping available from one to the other.
Thanks

Erm,
One way to find out, I reckon.
Good Luck,
Avi.

External SOAP client Accessing Webservice using built in Java Data type

We have built a webservice and deployed it on WLS. We accessed this from a swing
client it works fine.The webservice methods uses non-built in JAVA data types
as parameters.These are Value Objects and the JAVA Serializer and Deserializer
classes are generated using Ant task itself.The client coding uses Value objects
given by the Client_jar (generated using <Clientgen> ant task) to pass to the
webservice. We dont want to go by this way.Is there anyway were in we can pass
parameters to the method which expects non-built in java datatypes?
Why i am asking this is, i want to know how an external client (.Net client )
will be able to exceute my webservice (i.e., passing the required Object which
the method is expecting)?

Hi Anish,
Well first off, your web service doesn't send or receive "objects". It only sends
and recieves XML, which is in turn converted to/from Java objects at invocation
time. Second, a .NET (or Perl, or Python, or C++) client will be able to call
your web service, because the wsdl.exe tool (for .NET) will generate "programming
language specific" objects from the <types><schema> elements, in the WSDL of your
web service :-) The wsdl.exe tool will create C# objects from the WSDL, that will
convert XML to/from C# when your web service is called. That's the beauty of XML
schema - it's a "universal typing system", so it's not tied to a particular programming
language. The only issue is whether or not the web services platform vendor's
XML Schema/WSDL processor, can successfully process the WSDL. Some vendors have
more complete implementations of the WSDL and XML Schema specs than others, so
expect varying success here. The one in WLS 7.0 is pretty good, so you shouldn't
have too many problems consuming WSDL generated by .NET tools (or any other tool
for that matter).
Regards,
Mike Wooten
"Anish" <[email protected]> wrote:
>
We have built a webservice and deployed it on WLS. We accessed this from
a swing
client it works fine.The webservice methods uses non-built in JAVA data
types
as parameters.These are Value Objects and the JAVA Serializer and Deserializer
classes are generated using Ant task itself.The client coding uses Value
objects
given by the Client_jar (generated using <Clientgen> ant task) to pass
to the
webservice. We dont want to go by this way.Is there anyway were in we
can pass
parameters to the method which expects non-built in java datatypes?
Why i am asking this is, i want to know how an external client (.Net
client )
will be able to exceute my webservice (i.e., passing the required Object
which
the method is expecting)?

Java.sql.Types.??????

I know clob columns in an oracle database are java.sql.Types.CLOB. What are long raw columns defined as java.sql.Types.???
Thanks in advance,
kmw

Hi ,
Long has no correspondng type in Oracle.sql.Types.So u can access it using the getOBject and setObject.Why do u need to defing the long ?Is it for use i the getter and setter methods of ResultSet or Statements.If so , u have to use streaming and so there is really no need to worry abt the type definition as u are defaulting to an AsciiStream.
Hope it helps.

Java primitive types??

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