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Associative Array (Java and Delphi Cross Reference Guide)

By Mike Prestwood

Java versus Delphi: A side by side comparison between Java and Delphi.

Data Structures

Data structures allow you to store and work with data. Common data structures include arrays, associative arrays, etc.

Associative Array

[Other Languages]

A set of unique keys linked to a set of values. Each unique key is associated with a value. Think of it as a two column table. MyArray['CA'] = 'California' MyArray['AR'] = 'Arizona'

Languages Focus

Associative arrays are also known as a dictionary or a hash table in other languages.

Java: HashMap()

An associative array links a set of keys to a set of values. In Java, associative arrays are implemented as Maps.

This will print "Arizona."

Syntax Example:

import java.util.*;

public class Maps 
{
    public static void main(String[] args) 
    {
        Map states = new HashMap();
        
        states.put("CA", "California");
        states.put("FL", "Florida");
        states.put("AZ", "Arizona");

        System.out.println(states.get("AZ"));
    }
}

Associative Arrays in Java (a Map)

Delphi: TStringList Assoc Array

Object Pascal doesn't have a native associative array, but you can use a TStringList the same way. (Alternatively, search the Internet for TStringHash and THashedStringList classes for implementations of a true associative array).

Syntax Example:

var
  StateList : TStringList;
begin
  StateList := TStringList.Create;

  StateList.CommaText := 'CA=California, FL=Florida';

  ShowMessage('FL is ' + StateList.Values['FL']);
end;

Associative Arrays in Delphi/Object Pascal (Use TStringList)