Loading Java class files

[Priyatham Anisetty]

HI ,

I want to get all the classes names which are located there and get information from class files.

I used Reflection to get all the fields information which is like this

 getFieldsNames(){

  Class testClass = poly.exampleA.class;// this class is located in same project but under package named poly
 Field[] fieldsInClass = testClass.getDeclaredFields();
 
    for(int i=0; i<fieldsInClass.length;i++)
        {
            String newString = fieldsInCCR[i].getName();
            
        }
}

However the above code is giving me correct result for the given exampleA.class . But I have some class files located under Users/ramu/NetBeansProjects/Ext/build/classes/poly/
1) I want to get all .class file names under specified directory
2)I want to pass class file location to getFieldsNames() so that I can reuse the same code to get information of all classes(Just by changing the parameter).

Any suggestions please
Thanks in advance

[Pat Farrell]

Do you want the Java classes loaded? or just the files in the directory tree?

You can write (without too much work) a recursive tree walker for a directory, there is even one in my Java library on the web.

[Priyatham Anisetty]

Pat Farrell wrote:Do you want the Java classes loaded? or just the files in the directory tree?

You can write (without too much work) a recursive tree walker for a directory, there is even one in my Java library on the web.

All I want is to get the declared field names in every class .

[Pat Farrell]

Again, you have to be more specific. What classes do you mean? Those loaded from your jar file? on the disk? In the whole JVM?
There are probably more types, but I can't remember them all right now.

[Priyatham Anisetty]

Pat Farrell wrote:Again, you have to be more specific. What classes do you mean? Those loaded from your jar file? on the disk? In the whole JVM?
There are probably more types, but I can't remember them all right now.

I mean the ones which are in my disk .
I have two packages in my project named "packageA" and "packageB" . This is a GUI application . When the user launches the application he will create a .java file and save it in a specified directory. Then user will compile the classes with in the gui and saves the .class file in a directory such as Ext/build/classes/poly/.

In "PackageB" , I need to load that .class file and get the information(just Declared filed names) form that .class file .

I tried this

Class classToBeLoaded = Class.forName(className, true, URLClassLoader.newInstance(new URL[] { new File("/Users/priyathamanisetty/NetBeansProjects/Ext/build/classes/poly/").toURI().toURL()} ));

I am getting an error

Exception in thread "main" java.lang.ClassNotFoundException: PatientA
	at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
	at java.lang.Class.forName0(Native Method)
	at java.lang.Class.forName(Class.java:169)

[Pat Farrell]

Priyatham Anisetty wrote:I mean the ones which are in my disk .

Then I would skip the whole topic of the class loader, and classes that are in memory, and simply use the standard
Java functions to read the directory and get a list of the files. Filter to suit and you are done.

File and its listFiles() method are 99% of what you need.

You could use my DirWalker class from my open source Java library. http://www.pfarrell.com/java/pdflib.tar.gz