I would like to invoke a static method inside of a private class in Java using classloaders.
This is a short version of my classloader that I have been using.
URL[] jarURLArray = { server.lan.serverJAR().toURL() };
URLClassLoader serverClassLoader = new URLClassLoader(jarURLArray, this.getClass().getClassLoader());
Class mainClass = Class.forName("com.packagename.someclass", true, serverClassLoader);
Class sampleArgClass[] = { (new String[1]).getClass() };
Method mainMethod = mainClass.getDeclaredMethod("getSimplifiedName", sampleArgClass);
Object mainMethodInstance = mainClass.newInstance();
Object serverArgConverted[] = { args };
Object result = mainMethod.invoke(mainMethodInstance, serverArgConverted);
This code loads classes from a jar file and I am able to invoke classes under normal circumstances.
When I have a class, such as this one:
public final class someClass
{
private static Server server;
/**
* Static class cannot be initialized.
*/
private someClass()
{
}
public static int someValue()
{
return someValue;
}
I am unable to reach the someValue() method because of how the classloader creates new instances of the class, which, is not possible because it has a private constructor.
How can I reach the someValue method using a classloader?
The classloader isn't creating a new instance: you're telling the VM to create a new instance here:
Object mainMethodInstance = mainClass.newInstance();
Don't do that. Just pass in null as the target of the static method call:
Object result = mainMethod.invoke(null, serverArgConverted);
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