classloader

I have a tricky question. My java program is doing in a loop such things: loop: read external file with compiled java class into byte[] array. create a new instance of my own classloader. setbytes from the readed file to this instance of classloader. using created classloader create a new instance of object of the class from external file. call any method of the created object. And where the problem is. When I run this program in debug mode it behaves as I expect, so if external file changed classloader loads new version of class and executes new version (if file didn't change it loads old

I have a Java EE 6 application in which I'd like to use velocity to generate mails from a template. I have a @Named bean which is responsible for loading and filling a particular template. The project is a web application, so I placed my templates into WEB-INF/classes (which btw seems to be rather ugly, but I didn't find a more elegant solution by now) and used the ClasspathResourceLoader to access the files. The configuration is as follows: Properties props = new Properties(); props.setProperty("resource.loader", "class"); props.setProperty("resource.loader.class", "org.apache.velocity

I want to load specific jars in ScriptEngineManager using specific ClassLoader This constructor loads the implementations of ScriptEngineFactory visible to the given ClassLoader using the service provider mechanism. The problem when I tried to create Classloader File file = new File("c:\\myclasses\\"); try { // Convert File to a URL URL url = file.toURI().toURL(); // file:/c:/myclasses/ URL[] urls = new URL[]{url}; // Create a new class loader with the directory ClassLoader cl = new URLClassLoader(urls) And I'm getting also class that weren't in class for example Spring Class cls1 = cl

When I was studying android source code, I noticed that the general class loader in app is an instance of PathClassLoader , and there is two constructors in this class. One is like: public PathClassLoader(String dexPath, ClassLoader parent) { super(dexPath, null, null, parent); } and the other is like: public PathClassLoader(String dexPath, String libraryPath, ClassLoader parent) { super(dexPath, null, libraryPath, parent); } But I cannot find the call of the second constructor in the source code during the procedure of app launching. So where does the value of libraryPath param come from? As

I have a web application my requirement is to read some files and process it and persist the file content in database when the application starts. class MyUtil{ /** *Read the files */ public static void readFiles(){ File file = new File(ClassLoader.getSystemClassLoader().getResource("MyFile").toURI()); //NullPointerException // ClassLoader.getSystemClassLoader().getResource("MyFile") is giving null in servlet.init() method. if (file.isDirectory()) { //Read all the files and persist. } } } MyFile folder/dir is available in class path. When MyUtil.readFiles() is called in JUnit test case it

Can java String literals like "abc" be garbage collected?. If yes, how can we programatially prove that they are GCed? Yes, post Java7, String literals can be garbage collected if the class loader which loaded it gets garbage collected and there are no references to the string literal. Note : In Java -8, you will have to call GC twice in order to ensure that ClassLoaders get GCed (Metaspace.. pfff..Using a different GC won't help). Case -1 : //ClassLoaders don't get GCed. Code : import java.io.IOException; import java.io.InputStream; import java.lang.reflect.Field; // main class class