扫描仪无此元素异常

Question

got this code:

private void runGame() {
    boolean won = false;

    while(won == false) {
        System.out.println("DEBUG A");
        Player p = this.nextPlayer();
        System.out.println("DEBUG B");
        Scanner s = new Scanner(System.in);
        if(p.getPlayerType() == 0) {
            System.out.println("DEBUG C");
            // is Human
            BoardPrinter.printBoard(this.b);

            // Choose figure
            BoardPrinter.printFigureChoose(this.b.getFiguresFromPlayer(p.getSymbol()),p);

            int id = this.checkInput(1,this.b.getFiguresFromPlayer(p.getSymbol()).size(),s.nextInt());
            Figure f = this.b.getFiguresFromPlayer(p.getSymbol()).get(id - 1);

            // Choose move              
            ArrayList<Move> moves = b.checkMoves(f);
            BoardPrinter.printMoveChoose(moves,p);
            int moveID = this.checkInput(1,moves.size(),s.nextInt());
            Move m = moves.get(moveID - 1);

            // Execute the chosen move
            this.b.getCellAt(f.getLocation().getX(), f.getLocation().getY()).setSymbol(Symbol.EMPTY);
            f.setLocation(m.getTarget());
            this.b.getCellAt(m.getTarget().getX(), m.getTarget().getY()).setSymbol(p.getSymbol());

            // Check win conditions
            won = this.checkVictory(p);
            System.out.println("DEBUG D");
        }
        else {
            // KI stuff

            KI k = new KI(this.b,p,p.getPlayerType());
            Move m = k.think();     

            // Execute chosen move
            Figure f = this.b.getFigureAt(m.getStart());
            this.b.getCellAt(m.getStart().getX(), m.getStart().getY()).setSymbol(Symbol.EMPTY);
            f.setLocation(m.getTarget());
            this.b.getCellAt(m.getTarget().getX(), m.getTarget().getY()).setSymbol(p.getSymbol());
        }

        // Decomment this to get debug info
        //DebugPrinter.print(this.b);

        s.close();
    }
}

At the moment i do get an java.util.NoSuchElementException. Yes i know what i means and i googled a lot. Still i don't understand why it get's thrown. Also, i do get my Debug output only until "C".

If i move the Scanner initialization outside of the while loop i don't get that Exception anymore. However i do get stuck to, with the Code stopping at Debug "A" and nothing else.

I've encountered this both when having 2 human players. Fun fact: The first player will always work perfectly. The Player can see the Board, choose a Figure, choose a move and execute it. Whenever the next while() run starts and the 2nd player comes into account it fails as i described it above depended on where my Scanner initialization is.

Any guesses what's the problem? Thanks a lot! :)

Answer 1

You close your scanner at the end of your while loop. This means that the next time you try to read something from the scanner you'll get a NoSuchElementException .