I have two activities, MainActivityand MovieDetail and a java class MovieInfo.

MovieInfocorrectly initializes a static ArrayList< MovieInfo > with some MovieInfo instances.

MainActivity chooses one of the instantiated objects from the static ArrayList stored in MovieInfo and then passes it to MovieDetail activity via the putExtra method.

When I try to use the contains method in the static ArrayList from MainActivity with the instantiated object previously chosen it's working.

Why when I try the same from MovieDetail with the object received from MainActivity via the putExtra method it's doesnot recognize it anymore?

MainActivity

public class MainActivity extends AppCompatActivity {
SQLiteDatabase db;
static MovieInfo movie = null;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    MovieInfo.setPtr(ptr);

    db = ptr.getReadableDatabase();
    ptr.onCreate(db);

    if (this.movie == null) this.movie = new MovieInfo(db);

    listView = (ListView) findViewById(R.id.movieList);

    adapter = new ArrayAdapter<>(this,
            android.R.layout.simple_list_item_1, android.R.id.text1, MovieInfo.getArrayMovieInfo());

    . . .

    /* When the user clicks on an item via the adapater */
    MovieInfo  movieSelected    = (MovieInfo) listView.getItemAtPosition(position);

    /* Test 1 */
    boolean test = MovieInfo.getArrayMovieInfo().contains(movieSelected);
    Log.d("1. Object recognise -> ", test ? "True" : "False");
    Log.d("1. Object Content", movieSelected.toString());

    Intent movieDetail = new Intent();
    movieDetail.setClass(getBaseContext(), MovieDetail.class);
    movieDetail.putExtra("Movie", movieSelected);
    startActivity(movieDetail);
}

MovieDetail

public class MovieDetail extends AppCompatActivity {

MovieInfo movie = null;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.movie_detail);

    movie = (MovieInfo) getIntent().getSerializableExtra("Movie");
    boolean test = MovieInfo.getArrayMovieInfo().contains(movie);

    /* Test 2 */
    Log.d("2. Object recognise -> ", test ? "True" : "False");
    Log.d("2. Object Content", movie.toString());

    /* The array is populated */
    for (MovieInfo curr_movie : MovieInfo.getArrayMovieInfo()) {
        Log.d("ARRAY MOVIE CONTENT : ", curr_movie.getTitle()+"\n");
    }

    . . .

}

MovieInfo

public class MovieInfo implements Serializable {
private static SQLiteDatabase db = null;
private static SQLiteOpenHelper ptr = null;

private static ArrayList<MovieInfo> arrayMovieInfo = new ArrayList<>();

/* Movie */
private int id;
private String title;
private String director;
private float rate;
private int c_id;

/* Cinema */
private String c_wording;
private String c_address;
private String c_city;
private String c_date;

/* Genre */
private String g_wording;

/* Actor */
private String a_name;

public MovieInfo(SQLiteDatabase db) {
    this.db         = db;
    MovieInfo movie;

    String[] fields = new String[] {"m_id, m_title, m_rate, c_id, m_director"};
    Cursor c = db.query("movie", fields, null, null, null, null, null);
    if (c.moveToFirst()) {
        //List all results
        do {
            movie = new MovieInfo(c.getInt(0), c.getString(1), c.getInt(2), c.getInt(3), c.getString(4));
            getArrayMovieInfo().add(movie);
        } while(c.moveToNext());
    }
}
}

Logcat output Test 1

08-18 14:00:45.230 15666-15666/com.example..movieticket D/1. Object recognise ->﹕ True 08-18 14:00:45.230 15666-15666/com.example..movieticket D/1. Object Content﹕ Ex Machina Your Rate : 3.0/5 2015-08-03 21:30:00 from Maxim at Helsinki

Logcat output Test 2

08-18 14:00:45.339 15666-15666/com.example..movieticket D/2. Object recognise ->﹕ False 08-18 14:00:45.339 15666-15666/com.example..movieticket D/2. Object Content﹕ Ex Machina Your Rate : 3.0/5 2015-08-03 21:30:00 from Maxim at Helsinki

Logcat output to check Arraylist content

/com.example..movieticket D/ARRAY MOVIE CONTENT :﹕ Ex Machina /com.example..movieticket D/ARRAY MOVIE CONTENT :﹕ Birdman /com.example.*.movieticket D/ARRAY MOVIE CONTENT :﹕ Titre