Added a simple multithreadded java example

java/Hello.java

+class Hello {
+    private static class MyRunnable implements Runnable {
+	public MyRunnable(int id){
+	    this.id = id;
+	}
+	
+	public void run(){
+	    System.out.println("Hello from thread " + id );
+	}
+	
+	public int id;
+    }
+
+    private static int num_threads = 2;
+    
+    public static void main(String[] args) {
+	Thread t[] = new Thread[num_threads];
+	for(int i = 0; i < num_threads; i++){
+	    t[i]  = new Thread(new MyRunnable(i));
+	    t[i].start();
+	}
+    }
+}