Null Pointer Exception thrown when drawing an image

Question

I'm trying to make a fairly simple game, there is a player class that when instantiated an exception when trying to be drawn. The below code is the player class. Its whats being called to create the player object in the main game class.

package space.invaders;

import java.awt.Graphics;
import java.awt.Image;
import java.awt.Rectangle;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.io.IOException;
import java.net.URL;
import javax.imageio.ImageIO;
import javax.swing.JPanel;

/**
  *
* @author Your Name
* <Tristan, Teacher: Anthony , Last Edited: , Date Created, Program Description>
*/
public class player extends JPanel{
public static int px,py;   
public static int rx = 1, ry = 1, width =75, height = 50;
public Image player;
static Rectangle shot = new Rectangle(rx,ry,width,height);
static Graphics g;
String imagePath;
URL playerPath;



// draws the palyer    
public void paintPlayer(){
    playerPath = getClass().getResource("/graphics/player.png");
    try{
        player = ImageIO.read(playerPath);
    }catch(IOException io){
        System.out.print("The player picture didn't load properly");
    }
    g.drawImage(player, px, py, player.this);
}
// draws the shot
static void paintShot(){
    g.drawRect((int) shot.getX(), (int) shot.getY(),(int)shot.getWidth(),(int)shot.getHeight());
}
// moves the shot upwards, though might be unnececcary
static int moveShot (){
    for(ry = (int) shot.getY(); ry < 300; ry++){
        return ry;
    }
    return ry;
}

int setX(int x){
    return px;
}

int setY(int y){
    return py;
}

// I think this can be void since your * reminder to test that *
String setImage(String imagePath){        
    return imagePath;
}



// player movement control
public static class movement implements KeyListener {

    @Override
    public void keyTyped(KeyEvent e) {
        throw new UnsupportedOperationException("Not supported yet.");
    }

    @Override
    public void keyPressed(KeyEvent e) {
        if(e.getKeyCode() == KeyEvent.VK_RIGHT){
    rx += 5;

    }
    else if(e.getKeyCode() == KeyEvent.VK_LEFT){
    rx -= 5;

    }
    else if(e.getKeyCode() == KeyEvent.VK_UP){
    ry -= 5;

    }
    else if(e.getKeyCode() == KeyEvent.VK_DOWN){
    ry += 5;
    }
        else if(e.getKeyCode() == KeyEvent.VK_SHIFT){
            paintShot();
            moveShot();
        }
    }

    @Override
    public void keyReleased(KeyEvent e) {
        throw new UnsupportedOperationException("Not supported yet.");
    }

    }
}`

This is the main game class which is calling and creating the invader and player classes(same problem with invader as exists with player)

package space.invaders;

import java.awt.Color;
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JPanel;
import space.invaders.player.movement;

/**
 *
 * @author Your Name
 * <Tristan , Teacher: Anthony , Last Edited: , Date Created, Program Description>
 */
public class mainGame extends JFrame{
    public player p1 = new player();
    public mainGame(){        
        EventQueue.invokeLater(new Runnable(){
            @Override
            public void run() {
                createGUI();
                startGame();
                drawInvaders(1);

            }            
        });
    }
    void createGUI(){
        JFrame gameWindow = new JFrame("Space Invaders");
        JPanel observableWindow = new JPanel();
        gameWindow.add(observableWindow);
        observableWindow.setBackground(Color.black);
        gameWindow.setVisible(true);
        gameWindow.setSize(425,300);
        gameWindow.setDefaultCloseOperation(EXIT_ON_CLOSE);
        gameWindow.addKeyListener(new movement());
    }
    void startGame(){

        p1.setImage("/graphics/player.png");
        p1.setX(50);
        p1.setY(50);
        p1.paintPlayer();
    }
    void drawInvaders(int numInvaders){
        for(int i = 0; i < numInvaders; i++){
        int randX = (int) (Math.random() * this.getWidth());
        int randY = (int) (Math.random() * this.getHeight());
        invader a = new invader();
        a.setX(randX);
        a.setY(randY);
        a.newInvader();
        }
    }
}

Here is the error code

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
    at space.invaders.player.paintPlayer(player.java:31)
    at space.invaders.mainGame.startGame(mainGame.java:48)
    at space.invaders.mainGame$1.run(mainGame.java:26)
    at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:756)
    at java.awt.EventQueue.access$500(EventQueue.java:97)
    at java.awt.EventQueue$3.run(EventQueue.java:709)
    at java.awt.EventQueue$3.run(EventQueue.java:703)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:726)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
BUILD SUCCESSFUL (total time: 12 seconds)