How to find classes in a java package

i am writing a java IDE. i want to extract all class names from a java package eg. java.lang (through coding). how can i do that.
Thanks in advance

File file = new File("path to your jar file");
JarFile jf = new JarFile(file);
Enumeration e = jf.entries();
ZipEntry ze = null;
while(e.hasMoreElements()){
ze = (ZipEntry) e.nextElement();
ze.toString(); // gives you the file name
you have to understand java.util.jar java.util.zip packages for working with jar/zip files.
Hope this helps

Similar Messages

How to find classes in a particular package?

Does anyone know how in Java to find out what classes belong to a particular package? Or to find out what classes inherit from a particular class?
The reason why I'm asking this is that I want to create a BeanInfo property editor for a widget that will give me a list of any classes in a particular package. I know what that package can be and I know what the main class is that everyone should inherit from. I can easily create a beaninfo property editor with a string array of the classes, but I don't want to have to go back and maintain this code everytime I add another class to that package. I would love to use introspection but I haven't found the right commands to use yet.
Anyone have any ideas?
Thanks!

Not too difficult, the following snippet is used to gather information about a class. beanClass can be parsed to extract package name. and you ask the class directly about its superClasses and implemented Interfaces.
    private Class beanClass = null;
    private Class beanSuperClass = null;
    private Constructor[] constructors = null;
    private Field[] fields = null;
    private Method[] methods = null;
    private Object beanInstance = null;
    public setBeanDetail(Object o) {
        beanInstance = o;
        beanClass = o.getClass();
        beanSuperClass = beanClass.getSuperclass();
        constructors = beanClass.getConstructors();
        fields = beanClass.getDeclaredFields();
        methods = beanClass.getMethods();
    }have loads of fun with it.
tj...

How to find (classes,interface,subpackage info) in some package

Plz tell me if any one know how to find (classes,interface,subpackage) in some package
e.g. in java.io
"Above senerio in not concern with java doc
but tell me if an other way i.e by help of programming
i could find some package information"
as we know we find out any "object" classType , methods and fields information with help of "java.lang.reflect" API's
but how to find a package information as provided by jdk is in current use

You can locate the .zip or .jar file where the stuff is, and say either
unzip -l classes.zip
or
jar tvf classes.jar.
So you see the list of the classes in the given package.
Then you can say
javap -classpath classes.zip MyPackage.MyClass
to see the fields and methods of the given class.

How to find and install right java for ECC6 intstallation on AIX5.3

Hello
I wander how to find and install right java for ECC6 intstallation on AIX5.3. I went thruroughly thru note 723909 and underlying 716927, 1008311 and 1039948 notes but I still do not understand.
I guess I should logon to IBM site http://www.ibm.com/developerworks/java/jdk/aix/service.html
where I can choose :
" Java 1.4.2 64-bit "
and then :
"64-bit SDK 1.4.2 base images (at 1.4.2.0 level; in installp format) "->"Base SDK (required)
Java14_64.sdk.tar ((50001920)
then I assume (on AIX ) I should "tar xvf Java14_64.sdk.tar".
then I get extracted "Java14_64.sdk"
Is this ok?
I know on Linux(
from IBM site I downloaded "IBMJava2-amd64-142.rpm"
then I issued
"rpm -i IBMJava2-amd64-142.rpm "
and finally issued
"export JAVA_HOME=/opt/IBMJava2-amd64-142")
What in case of AIX5.3? Could you help me?

I was told to use smitty (just I am not familiar with it). furdermore i do not hace read.me file. the ziped files are:
Java14_64.ext
-rw-rr 1 202 bin    371712 Mar 2 2010 Java14_64.license
-rw-rr 1 202 bin      3072 Mar 2 2010 Java14_64.msg.ja_JP
-rw-rr 1 202 bin      3072 Mar 2 2010 Java14_64.msg.Ja_JP
-rw-rr 1 202 bin      3072 Mar 2 2010 Java14_64.msg.ko_KR
-rw-rr 1 202 bin      3072 Mar 2 2010 Java14_64.msg.zh_CN
-rw-rr 1 202 bin      3072 Mar 2 2010 Java14_64.msg.Zh_CN
-rw-rr 1 202 bin      3072 Mar 2 2010 Java14_64.msg.zh_TW
-rw-rr 1 202 bin      3072 Mar 2 2010 Java14_64.msg.Zh_TW
-rw-rr 1 202 bin   4888576 Mar 2 2010 Java14_64.samples
-rw-r----- 1 root root 67190784 Oct 4 09:53 Java14_64.sdk
-rw-rr 1 root root 77370639 Nov 20 19:36 Java14_64.sdk.tar.gz
-rw-r----- 1 root root 12612608 Oct 4 09:53 Java14_64.source

How to reload class file for java objects in CF MX7

I'm trying to create a simple java object for use in a CFML
page. According to the topic "About ColdFusion and Java objects" in
the CF developer's guide, I can compile my java module and put the
.class file in the CFusionMX7/wwwroot/WEB-INF/classes directory and
it'll be dynamically reloaded any time CF sees a new .class file
there. But the dynamic reload isn't happening; I have to restart
the CF server to get it to pick up a new version.
I don't believe this directory is in the "general JVM
classpath"; I don't find "classes" in the Java Class Path in the CF
Administrator's System Information page. And I have all the caching
options turned off on the "Server Settings > Caching" page, if
that has any bearing on it.
Are there any known issues around this dynamic reload
capability, or maybe a more definitive way to make sure the
WEB-INF/classes directory isn't in the classpath?
Thanks,
James

Yes, I understand. But if I'm reading it correctly, what
you're saying seems to contradict the documentation
http://livedocs.adobe.com/coldfusion/7/htmldocs/00001561.htm
ColdFusion dynamically loads classes that are either .class
files in the web_root/WEB-INF/classes directory or in JAR files in
the web_root/WEB-INF/lib directory. ColdFusion checks the time
stamp on the file when it creates an object that is defined in
either directory, even when the class is already in memory. If the
file that contains the class is newer than the class in memory,
ColdFusion loads the class from that directory.
http://kb.adobe.com/selfservice/viewContent.do?externalId=tn_18228&sliceId=1
Dynamic class reloading for Java servlets classes and
forcfobject (sic) Java classes is disabled by default in
ColdFusion MX. To enable dynamic class reloading, do the following:
Also, I seem to recall that setting worked in a prior
version. Though I would have to test it again on another machine to
be certain.

How to find the location of java class files at runtime?

Does anyonw have an idea how to get the file name of a java class given the binary name?
I mean how can I get the file name for my class myPackage.myClass?
I am looking for a function which takes "myPackage.myClass" as input and returns
"c:\\javaprojects\\myPackage\\myClass.class".
I tried to do it with the LassLoader class but it did not work. Does anyone have an idea if the Java core API already has a function which does that?
Thanks, Bernhard

Hi ,
It is a simple SAMPLE code , you think and build a logics to handle all classes.
Try this sample, It doesn't handle the inner classes you put logic to handle the logics for inner classes.
The inner class format is it contains the character $ in the File location but inside the code you put "." instedad of "$" you to find out or put trials.
package pkg1;
import java.io.* ;
import java.util.* ;
import java.util.zip.* ;
public class ClsB {
     private static Vector clsPaths ;
     public static Vector getPaths() {
          if( clsPaths == null ) {
               String paths = System.getProperty( "java.class.path" ) ;
               // In linux or solarise use the following
               // StringTokenizer st = new StringTokenizer( paths , ":\n" ) ;
               StringTokenizer st = new StringTokenizer( paths , ";\n" ) ;
               clsPaths = new Vector() ;
               while( st.hasMoreTokens() ) {
                    String path = st.nextToken() ;
                    File f = new File( path ) ;
                    if( f.exists() ) {
                         try {
                              f = f.getCanonicalFile() ;
                              clsPaths.add( f ) ;
                         }catch( IOException ioe ) { }
          return clsPaths ;
     public static String findClassPath( String fullClassName ) {
          Vector v = getPaths() ;
          for( int i = 0 ; i < v.size() ; i++ ) {
               File f = ( File ) v.get( i ) ;
               String path = findIn( f , fullClassName ) ;
               if( path != null )
                    return path ;
          return null ;
     static boolean isJar( File jar ) {
          if( jar.isDirectory() )
               return false ;
          try {
               ZipFile zf = new ZipFile( jar ) ;
               return true ;
          } catch ( ZipException ze ) {
               // It is not a jar file
               // you handle this
          } catch ( IOException ioe ) {
               ioe.printStackTrace() ;
          return false ;
     static String findIn( File dirOrJar , String clsName ) {
          if( isJar( dirOrJar ) ) {
               // It is something different because the class inside the jar file
               // Simply I return the jar file location and the entry name ,
               // but you put action what you want
               if( isInsideJar( dirOrJar , clsName ) ) {
                    // All archieve file using the path separator is '/'
                    return dirOrJar.getPath() + "!" + clsName.replace( '.' , '/' ) + ".class" ;
          } else {
               File f = new File( dirOrJar , clsName.replace( '.' , File.separatorChar ) + ".class" ) ;
               if( f.exists() ) {
                    return f.getPath() ;
          return null ;
     static boolean isInsideJar( File jar , String clsName ) {
          try {
               ZipFile zf = new ZipFile( jar ) ;
               // All archieve file using the path separator is '/'
               ZipEntry ze = zf.getEntry( clsName.replace( '.' , '/' ) + ".class" );
               return ( ze != null ) ;
          } catch ( ZipException ze ) {
               ze.printStackTrace() ;
          } catch ( IOException ioe ) {
               ioe.printStackTrace() ;
          return false ;
     public static void main(String[] args) {
          System.out.println( findClassPath( "pkg1.ClsB" ) );
          System.out.println( findClassPath( "pkg1.pkg2.ClsA" ) );
}

How to find classes in the package if package path

in java i want to find classes,Interface,Exception names which are presant
in the package..
for example
java.sql; if i give this it should return
class name
Date
Time
DrivarManager
pls helpme in this field

download the jdk documentation or view it here
http://java.sun.com/j2se/1.3/docs/api/index.html
The exact problem is i hava set the path to my application that path contains several jar's(contains classes,Interfaces) and classes with package structure,
now my need is if i run the application ,the application
should find out the classes and Interfaces for given package structure which are present in classpath...
for this i have to load all the classes to memory(using classes loader) . then find out the classes which are present in memory...
or
any other inbuilt method is there in java when i give path structure it find and give classes which are in class path..
for ex..
if i set path to jdk
then if i give the path like java.lang
it should give me the out put as
String (or) String.class
Double
Cloneable
(classes & interface in that package)

How to find classes in ABAP

Hi experts,
In java it is easy to find related classes for our requirement based on package and related methods by using API.But how to find that these are the classes are existing for this particular requirement in ABAP.In
se24 we can find existed classes but can not identified properly for our requirement.
Can anybody help me in this regard.
Thanks in Advance.

Hi,
As far as I know, SE24/se84 is the place where we can find the information about the global classes available in the system, to find the appropriate class for your requirement, you need to search using the wild card search and go thro' the documentation provided by SAP as SAP has provided a very good documentation(In most of the cases) on classes.
Rgds,

How to Find Classes Urgent!

I have loaded .class files using classLoader ..
i want to find calsses & interfaces which are present in perticular package structure(in memory)..if i use Package.getPackages() mathod
its returning me all the packages which are loaded in memory.using that package structure how to find the
classes and interface's
Advance Thanx

the problem is that its to hard to track the each classes and its packages.. i have more then 20 jars..each jar having morethen 25 classes with diff packge structure.. (more then one jar having same package structued classes )
so that i have loade all the classes using Systems class loader..
now my need is to find classes whichare present in perticular package structure..
for Ex. in system class loader it will automatically load java.jang.allclasses;
what i want is if i knew that package name (java.jang)
i should find the class name's like Object,String,Long...etc

How to include class files in no package?

hi,
I have a class file in a package called
pack.Test
and a class file not in a package called
Library
When I try to use Library from within pack.Test, it says theres no such class. I have my classpath setup correctly, and the files in the correct directories.
ie. on windows if %DIR% is the base directory then
%DIR%\Library.java
%DIR%\pack\Test.java
is how they are layed out.
Is there a way to get Library imported to pack.Test?
thanks,
asjf

What?!! It isn't considered legal to access a
root-level class from a higher level package?Well it's not now because your code won't compile, but
prior to 1.4 you could. I think the JLS has been
updated to say you can't import from the unnamed
namespace.Hmm! I must have missed that bit (not that I read it in any great detail, anyway!). I suppose it forces you to use packages, which is a good thing, IMHO.
What I was wondering about was, is the directory structure of classes strictly necessary, given that a class contains information on its package anyway? I know some IDEs don't require the source files to be in the right directory - they will check on the package statement, and locate the class file accordingly - but is it absolutely necessary for class files to be located according to their directory structure? I know the JLS says they have to be, but could the JLS be relaxed on this point, without breaking anything?
RObin

Problem finding native methods in java packages

Hi,
I have a java class which uses some native methods written in OCamL. I wrote a C file which calls the OCamL code, and created the corresponding shared library using the jni. I then tested my java file and everything works fine, I can nicely call the OCamL functions. However, I need this java file to be included in a package, but whenever I add the line:
package somepackage;
on top of the java code, my java file simply doesn't seem to find the C and OCamL implementation anymore :
javac -cp :./path/of/somepackage
-Djava.library.path=/full/path/of/somepackage MyProgram args
Exception in thread "main" java.lang.UnsatisfiedLinkError:functionName
at somepackage.ClassName.functionName(NativeMethod)
I have of course put everything (java, C, .h , libsomelibrary.so, and OCamL files) in a directory called somepackage, and written another java file which creates an instance of the first one from outside the package, imports the package, and calls its methods in main(). It just doesn't work anymore.
I then added a simple hello-world function (not C nor OCamL code) to the java file inside the package. And when invoked from outside, it worked. Question is then... Am I forgetting something to be done, in order to get C and CamL files efectively included in the java package (same as "package somepackage;" in C or OCaml, perhaps)??? Why isn't the java file able to find them inside its very own directory (having into account that without the package definition it worked well)?
Thanks,
PS Im using jsdk 1.4.1 on lunyx redhat 8.0

Did you change the name of the function in the library, too?
If the function name was
"Java_YourClass_functionname",
it should be now
"Java_path_to_your_package_YourClass_functionname".

How to find DB schema from Java codes

Hello,
Do you know whether there are java packages/classes to find the DDIC (schema) info of DB tables (the tables created by Netweaver Dev. studio)?
Thanks,
Martin

Hello,
when you are using a MaxDB as your database the tables created by the J2EE application belong to the SQL user SAP<SID>DB. For example your SID is called C11 the name of the SQL user is sapc11db
You can logon to the database with the SQL Studio. To see what users are in the database logon as the DBA ( default superdba,admin ) and run the select "select * from users"
Hope that helps, Stefan

How to find Classes to which characterstics are assigned

Hi,
How to find the classes to which a particular characterstics are assighned in 46B.
I have characterstics and I should able to find the class/classes to which it is assighned.
I have a BAPI BAPI_CHARACT_GETWHEREUSEDLIST which does the same as in 5.0 and I want the same FM or BAPI where it is used in 46B.
Best Regards,
Mark

Here's an example of a way to find classes based on characteristics if you need to write your own. Obviously this is for a report, but you get the idea.
select-options: s_atnam for cabn-atnam.
data: begin of t_class occurs 0,
        class like klah-class,
        atnam like cabn-atnam,
      end of t_class.
select klahclass cabnatnam into table t_class
   from klah inner join ksml
          on klahclint = ksmlclint
             inner join cabn
          on ksmlimerk = cabnatinn
       where cabn~atnam in s_atnam.

How to convert class files into java files??

Hey Guys,
I need a little help.
I want to know wheather we can view .class files as .java files or convert the .class to .java files.Is ther any tool or software for doing that.
Or in other words can i see the source code of any .class file..??
Plz do tell me if we can do that or any other way we can do that.
Regds,
Gokul

Sort of. A "decompiler" will take a class file and generate a source code file of source code that could be compiled to get the class file you started out with. However, it won't be the same source code that was originally used to create the class. Most notably, comments will be missing, and variable names will probably be meaningless.
And before you say "java is bad because you can decompile it", note that any language that you can execute you can theoretically decompile.
Also, you can view the raw byte codes. If you're familiar with assembly language, or better yet familar with java bytecodes and the JVM in particular, you can often find out what a particular method does just by viewing the byte codes.

How to find out what files a package has installed?

Sometime you installed a package, but you don't know the name of the command to run and you don't know the name and location of the configuration files. There are conventions but is there a way to show those information explicitly?

aberkoke wrote:
You can try
$locate
for example. you write
$locate firefox
and you will see all files about firefox.
That's a partial solution. Suppose I installed a package called gtk-vim, but the binary is gvim and I didn't know that. If I use
locate gtk-vim
it will not find "gvim".
Besides, different packages may install files with names identical or partially identical. What I want to find out is what files a specific package installed or removed, or changed, just like the deb package manager in ubuntu.

How to find classes in a java package

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