Java by API/java.lang/ClassLoader

ClassLoader: getSystemClassLoader()

   <source lang="java">
  

public class Main {

 public static void main(String[] args) {
   ClassLoader.getSystemClassLoader().setDefaultAssertionStatus(true);
   new Loaded().go();
 }

} class Loaded {

 public void go() {
   assert false: "Loaded.go()";
 }

}

 </source>
   
  
 
  

ClassLoader: loadClass(String name)

   <source lang="java">

import java.io.File; import java.net.URL; import java.net.URLClassLoader; public class Main {

 public static void main(String[] argv) throws Exception {
   File file = new File("c:\\");
   URL url = file.toURI().toURL(); 
   URL[] urls = new URL[] { url };
   ClassLoader cl = new URLClassLoader(urls);
   Class cls = cl.loadClass("com.mycompany.MyClass");
 }

}

 </source>
   
  
 
  

ClassLoader: setDefaultAssertionStatus(boolean enabled)

   <source lang="java">
  

public class Main {

 public static void main(String[] args) {
   ClassLoader.getSystemClassLoader().setDefaultAssertionStatus(true);
   new Loaded().go();
 }

} class Loaded {

 public void go() {
   assert false: "Loaded.go()";
 }

}

 </source>
   
  
 
  

extends ClassLoader

   <source lang="java">
 

import java.io.FileInputStream; import java.io.IOException; import java.lang.reflect.Method; class MyClassLoader extends ClassLoader {

 public Class findClass(String name) {
   byte[] classData = null;
   try {
     FileInputStream f = new FileInputStream("C:\\" + name + ".class");
     int num = f.available();
     classData = new byte[num];
     f.read(classData);
   } catch (IOException e) {
     System.out.println(e);
   }
   Class x = defineClass(name, classData, 0, classData.length);
   return x;
 }

} public class Main {

 static public void main(String args[]) throws Exception {
   MyClassLoader x = new MyClassLoader();
   Class c = x.loadClass(args[0]);
   Class getArg1[] = { (new String[1]).getClass() };
   Method m = c.getMethod("main", getArg1);
   String[] my1 = { "arg1 passed", "arg2 passed" };
   Object myarg1[] = { my1 };
   m.invoke(null, myarg1);
 }

}

 </source>