Convert sample java code to ruby to understand static variales in ruby

Question

can anybody help me to convert this simple java code to ruby.

class A {
 private static String[] chachedNames;

 public static String[] getNames(){
  if(chachedNames == null)
   chachedNames = prepareNames(); //This process will take 20sec to complete
  return chachedNames;
 }
}

I'm trying to understand basic memory caching on static method. How do implement same on Ruby.

Answer 1

Use @@ to assign a class variable that is shared with all instances of that class:

class A
  @@cached_names = nil

  def self.get_names
    @@cached_names = prepare_names if !@@cached_names
    @@cached_names
  end
end

The keyword self means assign the method to be a class method (analogous to a static method in Java). Without the self keyword, the method becomes an instance method.

Here's a nice summary of class and instance methods: