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What is the purpose of the static keyword in this simple example?

Possible duplicate:
When should there be a static method?

Typically, when writing a static method for a class, you can access this method with ClassName.methodName. What is the purpose of using “static” in this simple example and why should / should not be used here? also makes private static damage the goal of using static?

public class SimpleTest { 

   public static void main(String[] args) {
         System.out.println("Printing...");
         // Invoke the test1 method - no ClassName.methodName needed but works fine?
         test1(5);
   }

   public static void test1(int n1) {
         System.out.println("Number: " + n1.toString());
   }
   //versus
   public void test2(int n1) {
         System.out.println("Number: " + n1.toString());
   }
   //versus
   private static void test3(int n1) {
         System.out.println("Number: " + n1.toString());
   }
}

I looked through several guides. For instance. http://docs.oracle.com/javase/tutorial/java/javaOO/classvars.html

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