Need help finding the sum of an array list

Question

I'm making a mock up of iTunes, I suppose, for class. My only issue is that I can't figure out how to add all the durations of each sound file when it's stated in the array.
I've put the part I'm having trouble with in bold, it is located in the Jpod class. We're using a program called BlueJ for coding, which is why the commenting is slightly odd.
import java.applet.*;
import java.io.*;
import java.net.*;
public class SoundPlayer
    public SoundPlayer(String fileName, int duration)
        AudioClip testClip;
        URL testUrl;
        System.out.println("Playing " + fileName);
        try{
            testUrl=new URL("file:" + new File(".").getCanonicalPath() + "/" + fileName);
            testClip=Applet.newAudioClip(testUrl);
            testClip.play();
            Thread.sleep(duration*1000);
            testClip.stop();
        }catch(Exception e){ System.out.println(e.toString()); }
public class Sound
    private String author;
    private String fileName;
    private int duration;
     * Constructor for objects of class Sound
    public Sound(String newAuthor, String newFileName, int newDuration)
        // initialise instance variables
        author = newAuthor;
        fileName = newFileName;
        duration = newDuration;
     * Returns the duration of the sound file
     * @return     duration of the sound file
    public int getDuration()
        // returns duration
        return duration;
     * Returns the author of the sound file
     * @return     author of the sound file
    public String getAuthor()
        //returns author
        return author;
     * Prints the author, filename, and duration
    public void printSound()
        System.out.println("Author: " + author + " File name: " + fileName + " Duration: " + duration);
     * Plays the sound
     * @return     sound file
    public void playSound()
        new SoundPlayer("Lab4.wav",3);
import java.util.ArrayList;
import java.util.Iterator;
public class Jpod
    // instance variables - replace the example below with your own
    private ArrayList<Sound> playlists;
     * Constructor for objects of class Jpod
    public Jpod()
        playlists = new ArrayList<Sound>();
     * Adds a sound to the playlist
     * @param  sound   of type Sound
    public void addSound(Sound sound)
        // inserts the sound into the playlist
        playlists.add(sound);
     * Adds 3 sounds to a playlist
    public void createPlayList()
        Sound s;
        s = new Sound("Microsoft", "Lab4.wav", 2);
        addSound(s);
        s = new Sound("Dr. Evil", "DrEvil.wav", 4);
        addSound(s);
        s = new Sound("Arnold Schwarzenegger", "Terminator.wav", 2);
        addSound(s);
     * Remove desired sound object
     * @param indexNumber The number of the sound object to be removed
    public void removeSound(int indexNumber)
        if(indexNumber < 0){
            //Not a valid index number - do nothing
        else if(indexNumber < playlists.size()){
            //Valid indexNumber
            playlists.remove(indexNumber);
        else {
            //Not a valid index number - do nothing
     * Show the sound object
     * @param indexNumber The number of the sound object to be shown
    public void getSound(int indexNumber)
        if(indexNumber < 0){
            //Not a valid index number - do nothing
        else if(indexNumber < playlists.size()){
            //Valid indexNumber
            System.out.println(playlists.get(indexNumber));
        else {
            //Not a valid index number - do nothing
     * @return The number of sounds in the playlist
    public int getSize()
        return playlists.size();
     * List all sounds in the playlist
    public void indexPrintList()
        for(Sound playlist : playlists) {
            playlist.printSound();
     * Lists all sounds in the playlist using an iterator
    public void iteratorPrintList()
        Iterator<Sound> iter = playlists.iterator();
        while(iter.hasNext()) {
            ((Sound)iter.next()).printSound();
     * Gives the total duration of all sounds in the playlist
    *public void totalDuration()*
        *//currently prints all durations - still working on sum*
        *for(Sound playlist : playlists) {*
            *System.out.println(playlist.getDuration());*
     * Plays through all the sounds in the playlist
     * Extra Credit
    public void indexPlayList()
        for(Sound playlist : playlists) {
            playlist.playSound();
     * Plays through all sounds in the playlist using an iterator
     * Extra Credit
    public void iteratorPlayList()
        Iterator<Sound> iter = playlists.iterator();
        while(iter.hasNext()) {
            ((Sound)iter.next()).playSound();
}

Answer 1

not sure if I'm missing something here, but this could possibly be solved by initializing a variable to 0 before the for loop, and then adding each duration to this variable as you loop. This seems too trivial a solution though. Again, I may be missing something here.
something simple like:
public void calcSum()
    int i = 0;
    for(Fubar foo: fooList) {
        i += foo.getLength();
    System.out.println("Sum = " + i);
}Edited by: petes1234 on Oct 23, 2007 9:09 AM