Populating Object array with new Objects

Question

I'm trying to populate an object array with new objects. Here is the code:

Main class

public class Bejeweled extends JFrame{

public Bejeweled(){
    Board board = new Board();
    getContentPane().add(board);
    board.start();
}

public static void main(String[] args){
    Bejeweled game = new Bejeweled();
}

Board class

public class Board extends JPanel{

final int BOARDHEIGHT = 8;
final int BOARDWIDTH = 8;
Gem[] gems;

public Board(){
    gems = new Gem[BOARDHEIGHT * BOARDWIDTH];
}

public void start(){
    fillBoard();
}

public void fillBoard(){
    Arrays.fill(gems, new Gem());
    for(Gem gem : gems){
        System.out.println(gem.type); //**This was expected to print random numbers**
    }
}
}

Gem class

public class Gem {

public int type;

public Gem(){
    this.type = genType();
}

public int genType(){
    return (int) (Math.random() * 7);
}

}

The problem is that all objects appear to be the same. I know I should encapsulate type in the Gem class, but I'm trying to limit the amount of code I'm posting here.

A new Board gets created from the main class, in the Board class a Gem[] is filled with newly created Gems (class Gem).

Consider Arrays.fill(gems, new Gem());. In this line you create a single gem, and use the same gem to fill the array. Have you considered using a for loop instead? — tmrlvi
– tmrlvi, Commented May 10, 2015 at 22:34

chrylis -cautiouslyoptimistic- · Accepted Answer · 2015-05-10 22:34:40Z

2

Arrays.fill fills the array with the value you provide, which in this case is a particular instance of Gem. Instead, you need to use a for loop and set each of the array elements to a distinct Gem:

for(int i = 0; i < gems.length; i++) {
    gems[i] = new Gem();
}

Note that if you really have an 8x8 board, it's much preferable to have a Gem[8][8] than a Gem[8*8].

answered May 10, 2015 at 22:34

chrylis -cautiouslyoptimistic-

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8 Comments

Boris the Spider Over a year ago

Or Arrays.setAll.

The Coding Wombat Over a year ago

Thanks, yes, in my current version of the code I already use a two dimensional Object array, but thanks anyway :)

The Coding Wombat Over a year ago

setAll doesn't seem to exist for Object @BoristheSpider

Boris the Spider Over a year ago

@RichardKoetschruyter it does. I linked to it.

JamesB Over a year ago

mmm not sure about that. You would be surprised how much Java 6 and 7 is still out there.

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