I was given a robotapp from my professor which includes a game with the following code :

/* * This class represents a visual application for the "robot chase" game. */ package RobotGame;

/** * * @author jrsullins */

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

public class RobotApp extends JFrame implements ActionListener {

// Member variables for visual objects. private JLabel[][] board; // 2D array of labels. Displays either # for player, // * for pod, or empty space private JButton northButton, // player presses to move up southButton, // player presses to move down eastButton, // player presses to move right westButton; // player presses to move left // Current width and height of board (will make static later). private int width = 15; private int height = 15; // Player object /* Uncomment once you have created the Player class Player player; */ // Pod object stored in array for efficiency /* Uncomment once you have created the Robot class private Robot[] robots; */ int robotCount = 3; public RobotApp() { // Construct a panel to put the board on and another for the buttons JPanel boardPanel = new JPanel(new GridLayout(height, width)); JPanel buttonPanel = new JPanel(new GridLayout(1, 4)); // Use a loop to construct the array of labels, adding each to the // board panel as it is constructed. Note that we create this in // "row major" fashion by making the y-coordinate the major // coordinate. We also make sure that increasing y means going "up" // by building the rows in revers order. board = new JLabel[height][width]; for (int y = height-1; y >= 0; y--) { for (int x = 0; x < width; x++) { // Construct a label to represent the tile at (x, y) board[y][x] = new JLabel(" ", JLabel.CENTER); // Add it to the 2D array of labels representing the visible board boardPanel.add(board[y][x]); } } // Construct the buttons, register to listen for their events, // and add them to the button panel northButton = new JButton("N"); southButton = new JButton("S"); eastButton = new JButton("E"); westButton = new JButton("W"); // Listen for events on each button northButton.addActionListener(this); southButton.addActionListener(this); eastButton.addActionListener(this); westButton.addActionListener(this); // Add each to the panel of buttons buttonPanel.add(northButton); buttonPanel.add(southButton); buttonPanel.add(eastButton); buttonPanel.add(westButton); // Add everything to a main panel attached to the content pane JPanel mainPanel = new JPanel(new BorderLayout()); getContentPane().add(mainPanel); mainPanel.add(boardPanel, BorderLayout.CENTER); mainPanel.add(buttonPanel, BorderLayout.SOUTH); // Size the app and make it visible setSize(300, 350); setVisible(true); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // Auxiliary method to create game setup createGame(); } // Auxiliary method used to create board. Sets player, treasure, and walls. public void createGame() { /* Uncomment once you have created the Player class player = new Player(7, 1, width, height); */ /* Uncomment once you have created the Robot class // Construct array of Robot objects robots = new Robot[robotCount]; // Construct each Robot in the array, passing it its initial location, // fuel, and a reference to the Player. robots[0] = new Robot(7, 12, 8, player); robots[1] = new Robot(3, 10, 12, player); robots[2] = new Robot(10, 10, 10, player); */ // Call method to draw board drawBoard(); } // Auxiliary method to display player and robots in labels. public void drawBoard() { // "Erase" previous board by writing " " in each label for (int y = 0; y < height; y++) { for (int x = 0; x < width; x++) { board[y][x].setText(" "); } } /* Uncomment once you have created the Robot class // Get location of each robot and write # into that label (if not exploded). for (int p = 0; p < robotCount; p++) { if (!robots[p].isExploded()) { board[robots[p].getY()][robots[p].getX()].setText("#"); } } */ /* Uncomment once you have created the Player class // Write the player onto the board. board[player.getY()][player.getX()].setText("P"); */ } public void actionPerformed(ActionEvent e) { // Determine which button was pressed, and move player in that // direction (making sure they don't leave the board). /* Uncomment once you have created the Player class if (e.getSource() == southButton) { player.move("south"); } if (e.getSource() == northButton) { player.move("north"); } if (e.getSource() == eastButton) { player.move("east"); } if (e.getSource() == westButton) { player.move("west"); } */ /* Uncomment once you have created the Robot class // Move the pods and notify the pods about player location. Also invoke // method for random m direction changes. for (int p = 0; p < robotCount; p++) { robots[p].move(); } */ // Redraw the board drawBoard(); /* Uncomment once you have created the Player class if (player.getY() >= height-1) { gameOver(); } */ } public void gameOver() { /* Uncomment once you have created the Player class JOptionPane.showMessageDialog(this, "Reached exit with "+player.getHits()+ " hits"); */ northButton.setEnabled(false); southButton.setEnabled(false); eastButton.setEnabled(false); westButton.setEnabled(false); } /** * @param args the command line arguments */ public static void main(String[] args) { RobotApp a = new RobotApp(); } }

I put this into Robotapp.java... I also created a new file for both new classes "Robot" and "Player"

PLAYER CLASS:

/* * To change this license header, choose License Headers in Project Properties. * To change this template file, choose Tools | Templates * and open the template in the editor. */ public class Player {

//variable initialization private static int x; private static int y; private static int width; private static int height; private static int hits;

//Constructors public Player( int x , int y , int width , int height ){ this.x = x; this.y = y; this.width = width; this.height = height; }

//getter of X and Y public static int getX() { return x; }

public static int getY() { return y; }

public static int getHits(){ return hits; }

//Move of player public void move(String direction) { if (direction.equals("south") && y >= 0) { y--; } else if (direction.equals("north") && y <= height-1) { y++; } else if (direction.equals("west") && x >= 0) { x--; } else if (direction.equals("east") && x <= width-1) { x++; } }

//number of hits public static void hit() { hits++; } }

here is my ROBOT CLASS :

/* * To change this license header, choose License Headers in Project Properties. * To change this template file, choose Tools | Templates * and open the template in the editor */ package RobotGame;

/** * * @author bkisb */ public class Robot {

//variable initialization private static int x; private static int y; private static int fuel; private static Boolean exploded = false; private static Player player;

//Constructor public Robot(int x, int y, int fuel , Player player){ this.x = x; this.y = y; this.fuel = fuel; this.player = player; }

//getter of X and Y public static int getX() { return x; }

public static int getY() { return y; }

//checking if exploded or not public static Boolean isExploded(){ if( exploded == true ){ return true; } else { return false; } }

//Move of Robot public void move(){ if( x > player.getX() && fuel > 0 ){ x--; fuel--; } else if( x < player.getX() && fuel > 0 ){ x++; fuel--; } else if( y > player.getY() && fuel > 0 ){ y--; fuel--; } else if( y < player.getY() && fuel > 0 ){ y++; fuel--; }

if( player.getX() == x && player.getY() == y ){ player.hit(); exploded = true; } }

}

when i run the project, only the map shows up. When i try to run my Player class or Robot class as a file it tells me robotgame.Robot does not have a main method or robotgame.Player does not have a main method. Explain why this code has these errors and how can i fix it to run ?