Load jar dynamically at runtime?

Question

My current java project is using methods and variables from another project (same package). Right now the other project\'s jar has to be in the classpath to work correctly.

Answer 1

I needed to load a jar file at runtime for both java 8 and java 9+. Here is the method to do it (using Spring Boot 1.5.2 if it may relate).

public static synchronized void loadLibrary(java.io.File jar) {
    try {            
        java.net.URL url = jar.toURI().toURL();
        java.lang.reflect.Method method = java.net.URLClassLoader.class.getDeclaredMethod("addURL", new Class[]{java.net.URL.class});
        method.setAccessible(true); /*promote the method to public access*/
        method.invoke(Thread.currentThread().getContextClassLoader(), new Object[]{url});
    } catch (Exception ex) {
        throw new RuntimeException("Cannot load library from jar file '" + jar.getAbsolutePath() + "'. Reason: " + ex.getMessage());
    }
}