title: check if an object exist, using field string
body: <p>I have a Song class(field: String name) and an Album class (initialize an Arraylist fill with Song objects), I am adding a method (addSongAlbum(String name parameter))that first check if the song is already in the album. Everything works fine but now I want to check too if the song exist outside the album. How can I do this taking in consideration that the input of the method is a String?  </p>
  
  <pre><code>public void addSongToAlbum(String name){
      if(checkExist(name) == null){
          album.add(checkExist(name));
          System.out.println("Song "+name+" was successfully added");
      } else {
          System.out.println("This song is already in the album");
      }
  }
  
  private Song checkExist(String name){
      for(int i=0; i&lt;album.size(); i++){
          if(name.equals(album.get(i).getName())){
              return album.get(i);
          }
      }
      return null;
  }
  </code></pre>