Save an instance with different data in ArrayList

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Save an instance with different data in ArrayList

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#1 by (2 votes)
#2 by (0 votes)

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I'm trying to save different objects of the same class in an ArrayList, from an instance that is changing the value of the properties, I do not know if I explain. Here is a code that illustrates what I want to do.

Player Class:

package jugadores;

public class Jugador {
    private String nombre;
    private int puntuacion;

    public Jugador() {}
    public Jugador( String nombre, int puntuacion ) {
        this.nombre     = nombre;
        this.puntuacion = puntuacion;
    }

    public String getNombre() {
        return nombre;
    }
    public int getPuntuacion() {
        return puntuacion;
    }
    public void setNombre( String nombre ) {
        this.nombre = nombre;
    }
    public void setPuntuacion( int puntuacion ) {
        this.puntuacion = puntuacion;
    }

} //class

Main Class:

package jugadores;
import java.util.ArrayList;
import java.util.List;

public class Main {

    private static String player1     = "Pepe";
    private static String player2     = "Leo";
    private static int score_player1  = 100;
    private static int score_player2  = 92;
    private static Jugador player;
    private static List<Jugador> players_list = new ArrayList();


    public static void main( String[] args ) {

        //Jugador 1
        player = new Jugador( player1, score_player1 );
        players_list.add( player );

        //Jugador 2
        player.setNombre( player2 );
        player.setPuntuacion( score_player2 );
        players_list.add( player );

        test();
    }

    private static void test() {

        int size = players_list.size();

        for ( int x = 0; x < size; x++ ) {

            player = players_list.get( x );     
            tracePlayer( player );
        }
    }

    private static void tracePlayer( Jugador x ) {

        System.out.println( x.getNombre( ));
        System.out.println( x.getPuntuacion( ));
        System.out.println( "------------------" );
    }

} //class

When this is executed, what I want is for you to print the data of player 1, and then the data of player 2, that is to say that in the ArrayList one player is saved first and then the other, and it does not end up having copies of the last player saved.

To simplify, I only use two players, whose data I included in the Main class, but it has to work with a data source that will generate an unknown number of players. Since I do not know how many players there will be so I can not create an instance for each one.

java

asked by Orici 16.01.2017 в 01:39

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2 answers

0

You must make a second new, as the friend told you before, so that in the 2nd position of the list, there is a new object, otherwise you will have a list with two elements that both contain the same reference to the same object as the change of state 1 to state 2, and it stayed like this the last time it was set

Add the new to create a second instance

public static void main( String[] args ) {

    //Jugador 1
    player = new Jugador( player1, score_player1 );
    players_list.add( player );

    //Jugador 2


    player = new Jugador( player2, score_player2 );
    players_list.add( player );

    test();
}

answered by 16.01.2017 в 13:49

Bring data from the table with where in codeigniter What happens with the reference to the object?

score 2 · Accepted Answer

What happens is that what is stored in the ArrayList is a reference to the player object, every time you change player what you do is overwrite their data and in the ArrayList what there is is a pointer that says where to finally look for the data. If you want to use the same identifier "player" you must always then, before putting the data to declare it, it would be like that.

    //Jugador 1
    player = new Jugador( player1, score_player1 );
    players_list.add( player );

    //Jugador 2
    player = new Jugador() //<<<<<<<<<<<<<<<<<<<<<<
    player.setNombre( player2 );
    player.setPuntuacion( score_player2 );
    players_list.add( player );