Java: Implementieren von if-Anweisung mit switch cases, ArrayIndexOutOfBoundsException

Question

Stack Trace Hallo, ich arbeite an einer GUI für Monopol und ich habe eine Stufe erreicht, wo ich Benutzereingaben erhalten muss, die eine bestimmte Anzahl von Spielern verlangen würde und bereitstellen würde eine bestimmte Anzahl von Spielsteinen (Monopolstücken) basierend auf der Anzahl der angegebenen Spieler. Ich habe momentan ein Problem, das ich wirklich nicht so ernst nehmen sollte, wie es ist, wenn ich versuche, die Anzahl der Spieler für das Spiel anzugeben, das ich mit einer ArrayIndexOutOfBoundsException getroffen habe, und ich kann nicht zu identifizieren, wo oder was ist falsch und wie man es repariert. Danke für die Hilfe im Voraus und alle Änderungen oder Tipps für meinen Code, um es effizienter zu machen, sind ebenfalls willkommen. Ich werde alle notwendigen Programmdateien anhängen.

Ps. Ich habe den vollständigen Quellcode veröffentlicht, da ich dachte, dass es notwendig war, da eine verkürzte Version die Dinge nicht so klar machen würde. Danke noch einmal. P.p.s der Code funktioniert, wenn ich die Anzahl der Spieler im Quellcode ohne Nachfrage nach Benutzereingaben angeben, aber funktioniert nicht, wenn ich Benutzereingaben angeben. Monopoly Board Image

package sprint_One; 

/* 
* Code written by: lagosBoys A layered pane was used to place all components on the frame at the 
* desired locations 
*/ 

import java.awt.*; 
import java.awt.event.ActionEvent; 
import java.awt.event.ActionListener; 

import javax.swing.*; 
import javax.swing.border.Border; 
import javax.swing.border.TitledBorder; 

public class UI_Monopoly_Board extends JFrame { 
    /** 
    * 
    */ 
    private static final long serialVersionUID = 1L; 
    // Array of coordinates for the position of each square on the board 
    Point[] locations = {new Point(630, 643), new Point(570, 643), new Point(510, 643), 
     new Point(450, 643), new Point(390, 643), new Point(330, 643), new Point(270, 643), 
     new Point(210, 643), new Point(150, 643), new Point(95, 643), new Point(60, 643), 
     new Point(60, 573), new Point(60, 503), new Point(60, 433), new Point(60, 383), 
     new Point(60, 323), new Point(60, 273), new Point(60, 213), new Point(60, 153), 
     new Point(60, 93), new Point(60, 33), 

     new Point(120, 13), new Point(180, 13), new Point(230, 13), new Point(280, 13), 
     new Point(340, 13), new Point(400, 13), new Point(460, 13), new Point(520, 13), 
     new Point(580, 13), new Point(660, 60), new Point(660, 120), new Point(660, 160), 
     new Point(660, 220), new Point(660, 280), new Point(660, 340), new Point(660, 400), 
     new Point(660, 460), new Point(660, 520), new Point(660, 580), new Point(660, 640)}; 
    // The default position or starting point which is go 
    Point defaultPosition = new Point(600, 603); 

    private int players; 
    private Token[] token; 

    private static JPanel infoPanel; 
    private static JPanel commandPanel; 

    // creates a fixed length for the text field used by the command field 
    final static int field_Width = 20; 
    private static JTextField commandField = new JTextField(field_Width); 
    private static JLabel commandLabel = new JLabel("Enter Command: "); 

    private Border blackLineBorder; 
    private final int ROWS = 35; 
    private final int COLUMNS = 40; 
    private JTextArea textArea = new JTextArea(ROWS, COLUMNS); 
    private static JLabel echoed_Text_Label = new JLabel(); 
    private JLayeredPane layeredPane = getLayeredPane(); // The use of a JLayeredPane allows easier 
                 // and more flexible specification of 
                 // component positions 

    private static JLabel monopolyImageLabel; 

    public UI_Monopoly_Board() { 
    String playerNumber = JOptionPane.showInputDialog("Please enter the number of players"); 

// int tokenNumber = Integer.parseInt(playerNumber); 

// players = 6; 

    players = Integer.parseInt(playerNumber); 

    int offset = 10; 

    // Initialise tokens depending on number of players and spaces them out with offset 

    if(players >= 2 || players <= 6) 
    { 

     token = new Token[players]; 
     switch (players) { 
     case 2: 
      token[0] = new Token(); 
      token[0].setBounds(10, 10, 700, 700); 

      token[0].setPosition(600, 603); 

      token[1] = new Token(Color.red, null); 

      token[1].setBounds(10, 10, 700, 700); 

      token[1].setPosition(600 + offset, 603 + offset); 

      break; 

     case 3: 
      token[0] = new Token(); 

      token[0].setBounds(10, 10, 700, 700); 

      token[0].setPosition(600, 603); 

      token[1] = new Token(Color.red, null); 

      token[1].setBounds(10, 10, 700, 700); 

      token[1].setPosition(600 + offset, 603 + offset); 

      offset = offset + 10; 

      token[2] = new Token(Color.blue, null); 

      token[2].setBounds(10, 10, 700, 700); 

      token[2].setPosition(600 + offset, 603 + offset); 

      break; 

     case 4: 
      token[0] = new Token(); 

      token[0].setBounds(10, 10, 700, 700); 

      token[0].setPosition(600, 603); 

      token[1] = new Token(Color.red, null); 

      token[1].setBounds(10, 10, 700, 700); 

      token[1].setPosition(600 + offset, 603 + offset); 

      offset = offset + 10; 

      token[2] = new Token(Color.blue, null); 

      token[2].setBounds(10, 10, 700, 700); 

      token[2].setPosition(600 + offset, 603 + offset); 

      offset = offset + 10; 

      token[3] = new Token(Color.green, null); 

      token[3].setBounds(10, 10, 700, 700); 

      token[3].setPosition(600 + offset, 603 + offset); 
      break; 

     case 5: 
      token[0] = new Token(); 

      token[0].setBounds(10, 10, 700, 700); 

      token[0].setPosition(600, 603); 

      token[1] = new Token(Color.red, null); 

      token[1].setBounds(10, 10, 700, 700); 

      token[1].setPosition(600 + offset, 603 + offset); 

      offset = offset + 10; 

      token[2] = new Token(Color.blue, null); 

      token[2].setBounds(10, 10, 700, 700); 

      token[2].setPosition(600 + offset, 603 + offset); 

      offset = offset + 10; 

      token[3] = new Token(Color.green, null); 

      token[3].setBounds(10, 10, 700, 700); 

      token[3].setPosition(600 + offset, 603 + offset); 

      offset = offset + 10; 

      token[4] = new Token(Color.yellow, null); 

      token[4].setBounds(10, 10, 700, 700); 

      token[4].setPosition(600 + offset, 603 + offset); 

      break; 

     case 6: 
      token[0] = new Token(); 

      token[0].setBounds(10, 10, 700, 700); 

      token[0].setPosition(600, 603); 

      token[1] = new Token(Color.red, null); 

      token[1].setBounds(10, 10, 700, 700); 

      token[1].setPosition(600 + offset, 603 + offset); 

      offset = offset + 10; 

      token[2] = new Token(Color.blue, null); 

      token[2].setBounds(10, 10, 700, 700); 

      token[2].setPosition(600 + offset, 603 + offset); 

      offset = offset + 10; 

      token[3] = new Token(Color.green, null); 

      token[3].setBounds(10, 10, 700, 700); 

      token[3].setPosition(600 + offset, 603 + offset); 

      offset = offset + 10; 

      token[4] = new Token(Color.yellow, null); 

      token[4].setBounds(10, 10, 700, 700); 

      token[4].setPosition(600 + offset, 603 + offset); 

      offset = offset + 10; 

      token[5] = new Token(Color.cyan, null); 

      token[5].setBounds(10, 10, 700, 700); 

      token[5].setPosition(600 + offset, 603 + offset); 

      break; 

     default: 
      System.out.println("Invalid number of players"); 
     } 
    } 

    // The location of the image should be specified here 
    monopolyImageLabel = 
     new JLabel(new ImageIcon(this.getClass().getResource("Monopoly_board.jpg"))); 
    monopolyImageLabel.setBounds(-50, -30, 800, 750); 
    // The image and the tokens are added to the pane at different levels allowing them to overlap 
    layeredPane.add(monopolyImageLabel); 
    layeredPane.add(token[0], new Integer(1)); 
    layeredPane.add(token[1], new Integer(2)); 
    layeredPane.add(token[2], new Integer(3)); 
    layeredPane.add(token[3], new Integer(4)); 
    layeredPane.add(token[4], new Integer(5)); 
    layeredPane.add(token[5], new Integer(6)); 


    setSize(1500, 750); 
    setExtendedState(JFrame.MAXIMIZED_BOTH); // Sets the default window for the JFrame as a 
              // maximised 
    this.setResizable(false); 
    setTitle("Welcome to Monopoly"); 
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // Ensures the JFrame operation ends completely 
                // upon exiting the window 
    setVisible(true); 
    } 

    // This method displays the information panel and adds it to the pane 
    public void information_Panel() { 
    infoPanel = new JPanel(); 

    JScrollPane scrollPane = new JScrollPane(textArea); 
    blackLineBorder = BorderFactory.createLineBorder(Color.BLACK); 
    TitledBorder title = BorderFactory.createTitledBorder(blackLineBorder, "Information Panel"); 

    infoPanel.setBorder(title); 
    infoPanel.add(echoed_Text_Label, BorderLayout.NORTH); 

    // prevents any information from being added or deleted from the information panel. 
    textArea.setEditable(false); 
    infoPanel.add(scrollPane); 
    infoPanel.setBounds(750, 0, 600, 600); // specifies the desired coordinates of the panel being 
              // added to the layered pane 

    layeredPane.add(infoPanel); 
    } 

    // This method displays the command panel and adds it to the pane 
    public void command_Panel() { 
    commandPanel = new JPanel(); 

    blackLineBorder = BorderFactory.createLineBorder(Color.BLACK); 

    JButton button = new JButton("Enter"); 

    /* 
    * implements the actionlistener interface on the button to help execute a command when the 
    * button is clicked 
    */ 
    button.addActionListener(new ActionListener() { 
     public void actionPerformed(ActionEvent e) { 
     if (commandField.getText().isEmpty()) { 
      String command = null; 
      textArea.append(command); 
     } 

     else { 
      String command = commandField.getText(); 
      textArea.append(command + "\n"); 
      commandField.setText(""); 
     } 
     } 
    }); 

    // This invokes the actionListeners interface for actionPerformed (quick way to implement a key 
    // listener on the keyboards Enter button) 
    getRootPane().setDefaultButton(button); 

    commandPanel.setBorder(BorderFactory.createLineBorder(Color.BLACK)); 
    button.setPreferredSize(new Dimension(65, 20)); 
    commandPanel.add(commandLabel); 
    commandPanel.add(commandField); 
    commandPanel.add(button); 
    commandPanel.setBounds(800, 630, 500, 50); // specifies the desired coordinates of the panel 
               // being added to the layered pane 

    layeredPane.add(commandPanel); 
    } 

    // Method which moves the tokens round the board one at a time 
    public void moveTokens() throws InterruptedException { 

    int i, j, offset; 
    offset = 0; 

    for (i = 0; i < token.length; i++) { 
     for (j = 0; j < locations.length; j++) { 
     token[i].setPosition(locations[j].x, locations[j].y); 
     repaint(); 
     // controls the movement speed of the tokens across the board allowing for easy detection of 
     // their movement 
     Thread.sleep(300); 
     } 

     token[i].setPosition(defaultPosition.x + offset, defaultPosition.y + offset); 
     offset = offset + 15; 
    } 
    } 



    public static void main(String[] args) throws InterruptedException { 
    // TODO Auto-generated method stub 
    UI_Monopoly_Board obj = new UI_Monopoly_Board(); 
    obj.information_Panel(); 
    obj.command_Panel(); 
    obj.moveTokens(); 
[enter image description here][1] 
    } 

} 


package sprint_One; 

import java.awt.*; 
import javax.swing.JComponent; 

/* 
* Each token has variables for location, dimension and shape, there's a constructor that allows the 
* user to specify the colour of the shape the necessary accessor and mutator functions are provided 
*/ 
public class Token extends JComponent { 
    /** 
    * 
    */ 
    private static final long serialVersionUID = 1L; 
    private int length; 
    private int breadth; 
    private int x; 
    private int y; 
    private Shape shape; 
    private Color color; 
    private String name; 
    private int balance; 

    public Token() { 
    super(); 
    setVisible(true); 
    this.length = 15; 
    this.breadth = 15; 
    this.x = 5; 
    this.y = 5; 
    this.shape = new Rectangle(this.x, this.y, this.length, this.breadth); 
    this.color = Color.BLACK; 
    this.name = ""; 
    this.balance = 20; 
    } 

    public Token(Color color, String name) { 
    this(); 
    this.color = color; 
    this.name = name; 
    } 

    public int getX() { 
    return this.x; 
    } 

    public int getY() { 
    return this.y; 
    } 

    // Method which specifies the x and y coordinates of the tokens 
    public void setPosition(int x, int y) { 
    this.x = x; 
    this.y = y; 
    } 

    public void paintComponent(Graphics g) { 
    Graphics2D g2 = (Graphics2D) g; 
    super.paintComponent(g); 

    g2.setColor(color); 
    g2.fill(shape); // fills the shape with the colour specified 

    g2.draw(this.shape); 
    } 

    public Shape getShape() { 
    // TODO Auto-generated method stub 
    return this.shape; 
    } 
} 

Answer 1

Ok, sollten Sie lernen, wie man einen Debugger verwenden ...

Das ist die Linie, die Ihre Fehler verursacht:

layeredPane.add(token[2], new Integer(3)); 

Und Sie initialisieren token wie folgt aus:

if(players >= 2 || players <= 6) 
{ 
    token = new Token[players]; 

Also, was ist, wenn players 2 ist? Sie erhalten eine ArrayIndexOutOfBoundsException.

Noch ein Tipp:

layeredPane.add(token[0], new Integer(1)); 

ist nicht so lesbar wie

layeredPane.add(token[0], 1);