Useful Java Programming Code

Common java classes to import at the top of your code.

• import java.io.*;
• import java.net.*;
• import java.util.*;

Simple input from a user using standard input"

public ProvisionCell AskUser(LinkedListQ Plist, Agent Local) throws Exception {
BufferedReader inFromUser = new BufferedReader(new InputStreamReader(System.in));
System.out.println("Which State? ");
String query = inFromUser.readLine();
}
Elements of interest:

• throws Exception -- passes exception handling up to the next level
• Example input line from Java using System.in
• Output prompt question to System.out
• .readLine() to actually retrieve the user's input

DECAF Util class

see Util.java in the DECAF architecture files.

Examples:

• String message = new String(Util.getValue(Plist, "MESSAGE"));
• K.addFieldValuePair("reply-with", Util.getValue(Plist,"REPLY-TOKEN"));
• Util.send(K.toString());

Explanation:

• Util.getvalue()-- Extracts the value given a keyword
• The incoming Plist always has a "MESSAGE" in it.
• REPLY-TOKEN -- a computer generated tag for uniqueness in message responses
• Util.send() -- send a KQML message from a method, normally used for initialization for sending a message to oneself.

KQML Message Structure Example

Making and populating a new KQML message:
KQMLmsg K = new KQMLmsg();
K.addFieldValuePair("performative", "ask-all");
K.addFieldValuePair("sender", Local.getName());
K.addFieldValuePair("receiver", "Matchmaker");
K.addFieldValuePair("reply-with", Util.getValue(Plist, "REPLY-TOKEN"));
K.addFieldValuePair("language", "DECAF");
K.addFieldValuePair("ontology", "Matchmaker");
K.addFieldValuePair("content", ":keywords Information Extraction "+":percentage 100 :agentNbr 0");
return new ProvisionCell(K.getKQMLString(),"OK");