Stack and Queue

Consider a class called Configuration. This class ââ?¬Å?encapsulatesââ?¬Â? the configuration management for any software system. For example, once created, the user can simply ask the configuration object for value(s) to a certain configuration key. Letââ?¬â?¢s take a look at a few examples:
String filename = ââ?¬Å?config.txtââ?¬Â?;
Configuration config = new Configuration( new File(filename) );
int numUser = config.getInteger( ââ?¬Å?num_usersââ?¬Â? );
String name = config.getString( ââ?¬Å?player1ââ?¬Â? );
In the above example, the config object is constructed and its contents are expressed in the file config.txt. The format of the config.txt file is as followed.
key = value
key2 = value2
## lines with comments begins with the #

The complete Configuration class should implement the following methods:
Class Configuration {
// constructors
Configuration() { � }
Configuration( File file) { � }
Configuration(String filename) { � }
// accessors
int getSize() { � }
String getString( String key ) { � }
int getInteger( String key ) { � }
String[] getKeys() { � } // return all keys
// mutators
void push(String key, String value) { }
String[] pop() { } // returns String array[] = { key, value }
}

Your Configuration class will have two sub classes: (1) ConfigurationQueue and (2)
ConfigurationStack. The push and pop functions will behave differently depending on whether your class is a Queue or a Stack.

Your App class is given and you should not change this class at all. Your homework will require creating three files: Configuration.java ConfigurationQueue.java and ConfigurationStack.java.