Oprettelse af ArrayList i Java

Java kode 

 import java.util.ArrayList;
  import java.util.Collections;
  
  public class Catalog {
  
      //felt-variable
      public ArrayList<CD> archive;
  
      //constructor
      public Catalog()
      {
          archive = new ArrayList<CD>();
      }
  
      // En masse mellemliggende kode uden nogen relevans for spørgsmålet :P
  
  
  //main-metoden der demonstrerer vores kode
      public static void main(String[] args)
      {
  
          //Opret objekter af typen Catalog og af typen CD.
          
          ArrayList<Catalog> katalog = new ArrayList<Catalog>();
          katalog.add(new Catalog());
          katalog.get(0).archive.add(new CD("Min Første CD"));
         
  
      }    
  }

Java kode 

 import java.util.ArrayList;
 import java.util.concurrent.TimeUnit;
 
 
 public class Catalog {
     
     private ArrayList<CD> archive = new ArrayList<CD>();
     
     public void addCD(CD cd){
         this.archive.add(cd);
     }
     
     
     public int getSize(){
         return this.archive.size();
     }
     
     public CD getCDWithAlbum(String album){
         
         for(CD c: archive){
             if(c.getAlbum().equals(album)){
                 return c;
             }
         }        
         return null;
     }
     
     public ArrayList<CD> getCDsWithArtist(String artist){
         ArrayList<CD> results = new ArrayList<CD>();
         
         for(CD c : archive){
             if(c.getArtist().equals(artist)){
                 results.add(c);
             }
         }
         
         return results;
         
     }
     
         
     public static void main(String[] args) {        
         Catalog archive = new Catalog();
         //Der bliver tilføjet en CD til Kataloget
         CD cd = new CD("IMMORTAL", "Michael Jackson");
         //Der bliver tilføjet en sang til CD'en
         cd.addSong(new Song("Workin' Day and Night",TimeUnit.MINUTES.toMillis(5)+TimeUnit.SECONDS.toMillis(14)));
         //CD'en bliver nu tilføjet til kataloget
         archive.addCD(cd);
                 
         System.out.println("CD arkivet er nu oppe på " + archive.getSize() + " CD'er");
         System.out.println("CD'erne med Michael Jackson hedder : " + archive.getCDsWithArtist("Michael Jackson"));
         System.out.println("Antallet af sange på albumet IMMORTAL : " + archive.getCDWithAlbum("IMMORTAL").getSize());
         
     }
 
 }

Java kode 

 import java.util.ArrayList;
 
 
 public class CD {
     private String album, artist;
     private ArrayList<Song> songs = new ArrayList<Song>();
     
     public CD(String album, String artist){
         this.album = album;
         this.artist = artist;
     }
     
     
     public void addSong(Song song){
         this.songs.add(song);
     }
     
     public Song getSongWithName(String name){
         for(Song s: songs){
             if(s.name.equals(name)){
                 return s;
             }
         }        
         return null;        
     }
     
     public String getAlbum(){
         return this.album;
     }
     
     public String getArtist(){
         return this.artist;
     }
     
     public int getSize(){
         return this.songs.size();
     }
     
     @Override
     public String toString() {
         return this.album + " by : " + this.artist;
     }
 }

Java kode 

 public class Song {
     //in miliseconds
     long duration;
     String name;
     
     public Song(String name, long duration){
         this.duration = duration;
         this.name = name;
     }
     
     public String getName(){
         return this.name;
     }
     
     public long getDuration(){
         return this.duration;
     }
 
 }

Java kode 

 ArrayList<String> list = new ArrayList<String>();
         
 list.add(new String("Hej"));
 list.add("test");
         
 System.out.println(Arrays.toString(list.toArray()));