How to store an array in a Java properties file

Below describes how to store a two-dimensional array in a properties file.

Delineate the items in the array by commas and semicolons.

The properties file would be like:

myProperty=name1,age1,job1,location1;name2,age2,job2,location2;

So each person is divided by a semicolin, but the attribute of that person by a comma. The same code works with any amount of attributes per person.

Split up the property into a String[][] variable type:

    //get array split up by the semicolin
  String[] a = propFile.getProperty(propertyName).split(";");

  //create the two dimensional array with correct size
  String[][] array = new String[a.length][a.length];

  //combine the arrays split by semicolin and comma 
  for(int i = 0;i < a.length;i++) {
      array[i] = a[i].split(",");
  }

Now you have a two dimensional array from a property file!

Below is a complete example:


Properties File

#delineated by Name,Capital,Nickname;Name,Capital,Nickname; etc....
stateInfo=California,Sacramento,The Golden State;Pennsylvania,Philadelphia,Keystone State;Texas,Austin,Lone Star State

Java Code

package myProject;

import java.io.FileInputStream;
import java.util.Properties;

public class Main {

//Key for 2nd part of array
final static int NAME = 0;
final static int CAPITAL = 1;
final static int NICKNAME = 2;

public static void main(String[] args) throws Exception {

  //get properties file
  Properties prop = new Properties();
  prop.load(new FileInputStream("C:\\myStatesPropertiesFile.txt"));

  //get two dimensional array from the properties file that has been delineated
  String[][] stateInfos = fetchArrayFromPropFile("stateInfo",prop);


  //below code will print out all the states, their capitals, and nicknames
  for (int i = 0; i < stateInfos.length; i++) {
      System.out.print("State "+ i + ":");
      System.out.print("\n");
      System.out.print("Name: " + stateInfos[i][NAME]);
      System.out.print("\n");
      System.out.print("Capital: " + stateInfos[i][CAPITAL]);
      System.out.print("\n");
      System.out.print("NickName: " + stateInfos[i][NICKNAME]);
      System.out.print("\n");

  }
}

/**
* Creates two dimensional array from delineated string in properties file
* @param propertyName name of the property as in the file
* @param propFile the instance of the Properties file that has the property
* @return two dimensional array
*/
private static String[][] fetchArrayFromPropFile(String propertyName, Properties propFile) {

  //get array split up by the semicolin
  String[] a = propFile.getProperty(propertyName).split(";");

  //create the two dimensional array with correct size
  String[][] array = new String[a.length][a.length];

  //combine the arrays split by semicolin and comma 
  for(int i = 0;i < a.length;i++) {
      array[i] = a[i].split(",");
  }
  return array;
}
}