Get a Map from an ArrayList of Map in Java for Android

Question

I'm developing an app for Android. My app parse an XML remote file and I store the data for the first tag in an ArraList of Maps and the data of the second tag in another ArrayList of Maps. I will post here my XML:

<?xml version="1.0" encoding="UTF-8"?>
<Programs>
    <Program programNumber="1" imgURL="http://www.photovideolife.com/userfiles/Placeholder%2001.jpg" description="Lorem ipsum dolor sit er elit">
        <Episode pN="1" episodeNumber="1" transmissionName="Titolo" date="29 Giu 2013" time1="14:30" time2="" channel="IRIS" channelLogo="http://indiscrezioni.files.wordpress.com/2010/06/logo_iris.jpg">
        </Episode>
        <Episode pN="1" episodeNumber="1" transmissionName="Titolo" date="29 Giu 2013" time1="" time2="16:30" channel="La7" channelLogo="http://www.tabaccheriavenza.it/media/logo/la7.jpg">
        </Episode>
        <Episode pN="1" episodeNumber="2" transmissionName="Titolo" date="01 Lug 2013" time1="14:30" time2="" channel="IRIS" channelLogo="http://indiscrezioni.files.wordpress.com/2010/06/logo_iris.jpg">
        </Episode>
        <Episode pN="1" episodeNumber="2" transmissionName="Titolo" date="01 Lug 2013" time1="" time2="16:30" channel="la7" channelLogo="http://www.tabaccheriavenza.it/media/logo/la7.jpg">
        </Episode>
    </Program>
    <Program programNumber="2" imgURL="http://mesa.umich.edu/files/mesa/field/image/placeholder2.png" description="Lorem ipsum dolor sit er elit">
        <Episode pN="2" episodeNumber="1" transmissionName="Titolo 1" date="30 Giu 2013" time1="13:30" time2="" channel="Rai 1" channelLogo="http://i822.photobucket.com/albums/zz145/Mattelufregn/Loghi%20canali%20tv/70px-Logo_Rai_1_2010svg50x50.png">
        </Episode>
        <Episode pN="2" episodeNumber="1" transmissionName="Titolo 1" date="30 Giu 2013" time1="" time2="18:30" channel="Rai 5" channelLogo="http://www.tuttotv.info/wp-content/uploads/2011/04/logo_rai5_50.jpg">
        </Episode>
        <Episode pN="2" episodeNumber="2" transmissionName="Titolo 1" date="01 Lug 2013" time1="13:30" time2="" channel="Rai 1" channelLogo="http://i822.photobucket.com/albums/zz145/Mattelufregn/Loghi%20canali%20tv/70px-Logo_Rai_1_2010svg50x50.png">
        </Episode>
        <Episode pN="2" episodeNumber="2" transmissionName="Titolo 1" date="01 Lug 2013" time1="" time2="18:30" channel="Rai 5" channelLogo="http://www.tuttotv.info/wp-content/uploads/2011/04/logo_rai5_50.jpg">
        </Episode>
    </Program>
    <Program programNumber="3" imgURL="http://wp.contempographicdesign.com/wp_paramount/wp-content/themes/paramount/images/image_placeholder_lrg.jpg" description="Lorem ipsum dolor sit er elit">
        <Episode pN="3" episodeNumber="1" transmissionName="Titolo 2" date="30 Giu 2013" time1="10:30" time2="" channel="Canale 5" channelLogo="http://www.mozaic.qa/logo/canale5.jpg">
        </Episode>
        <Episode pN="3" episodeNumber="1" transmissionName="Titolo 2" date="30 Giu 2013" time1="" time2="17:30" channel="Italia 1" channelLogo="http://upload.wikimedia.org/wikipedia/it/thumb/3/30/Logo_Italia_1.svg/50px-Logo_Italia_1.svg.png">
        </Episode>
        <Episode pN="3" episodeNumber="2" transmissionName="Titolo 2" date="01 Lug 2013" time1="10:30" time2="" channel="Canale 5" channelLogo="http://www.mozaic.qa/logo/canale5.jpg">
        </Episode>
        <Episode pN="3" episodeNumber="2" transmissionName="Titolo 2" date="01 Lug 2013" time1="" time2="17:30" channel="Italia 1" channelLogo="http://upload.wikimedia.org/wikipedia/it/thumb/3/30/Logo_Italia_1.svg/50px-Logo_Italia_1.svg.png">
        </Episode>
    </Program>
</Programs>

At the end of parsing I've an ArrayList for programs and an ArrayList for Episode. You can see that Programs and Episode have a common field (programNumber and pN), now I need to take the data stored in ArrayList of Episode for the right program. How I can do that? I found on the web this solution:

for (HashMap<String, String> programsMap : programs) {
    for (Map.Entry<String, String> entry : programsMap.entrySet()) {
   // I added some code here
  }
}

How I can solve this problem? Thank you for the suggestion.

Answer 1

String programNumber = "3";
// create the result list (empty initially)
List<Map<String, String>> episodesForProgramNumber = new ArrayList<>();

// loop through all the episodes
for (Map<String, String> episode : allEpisodes) {

    // if the current episode has the given program number, add it to the result
    if (programNumber.equals(episode.get("pN")) {
        episodesForProgramNumber.add(episode);
    }
}

But Java is an OO language. You shouldn't use maps to store the data. You should use objects of type Program and Episode . With Program containing a List<Episode> .

Answer 2

You are thinking relational. In an SQL database you would do something like you intend to. Map the episodes to the program by their key.

I would do this a little more object oriented. Create a Program and an Episode class with the same attributes as the elements in your XML structure have. Besides that your Program class should have a list of episodes (like this: List<Episode> episodes ) where your add all the episodes that belong to the program.

Answer 3

It's true that you need to use object, but I guess that the solution of JB Nizet will works. Next time use object.