Java HashMap 空指针异常怎么处理

[FishingProgrammer]

package indi.fishing.PlaneGame.PlaneGamev1;
/**
 * 作者:fishing
 * 创作时间:2018/1/17
 * 更新日期:2018/1/28
 * 
 */

import javax.imageio.ImageIO;
import javax.swing.*;

import java.io.File;
import java.io.IOException;
import java.util.HashMap;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.awt.image.BufferedImage;

@SuppressWarnings("serial")
public class PlaneGame extends JFrame {
	/**
	 * 作者:fishing
     * 窗口
	 */
	public static void main(String[] args) throws IOException{
		new PlaneGame();
	}
	
	//找到游戏的资源目录
	public static String path1 = System.getProperty("user.dir")+"\\File\\indi\\fishing\\PlaneGame\\photos";
	//存储图片文件
	public static HashMap<String,BufferedImage> maps1 = new HashMap<>();
	//加载游戏资源
	static{
		//拿到该目录下面所有的文件
		File[] files1 = new File(path1).listFiles();
		for (int i = 0; i < files1.length; i++){
            //保存起来
			try {
				maps1.put(files1[i].getName(),ImageIO.read(files1[i]));
			} catch (IOException e) {
				e.printStackTrace();
			}
            //System.out.println(files[i].getName());
		}
	}
	/*创建一个构造方法*/
	PlaneGameClassOne jp;
	public PlaneGame(){
		//设置标题
		this.setTitle("fishing 打飞机v1");
		//设置窗口居中
//		this.setLocationRelativeTo(null);		
		//点击x结束运行
		this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);		
		//设置窗体大小
		this.setSize(640, 700);
		//设置窗口不可改动大小
		this.setResizable(false);
		//创建一个小面板
		PlaneGameClassOne jp = new PlaneGameClassOne();
		this.setContentPane(jp);
		this.addKeyListener(new KeyListener());
		//设置窗口可见
		this.setVisible(true);
	}
	/**添加一个适配器*/
	class KeyListener extends KeyAdapter{
		public void keyPressed(KeyEvent ex) {
			jp.keyPressed(ex);
		}
	}
}
    /**
	 * 作者:fishing
     * 容器
	 */

@SuppressWarnings("serial")
class PlaneGameClassOne extends JPanel {  //throws NullPointerException 

	/*按下键盘*/
	public void keyPressed(KeyEvent e) throws NullPointerException{
		//键码值
		try {
			if(e.getKeyCode() == KeyEvent.VK_W){
		   		planePoint.y -= 10;
		   	}if(e.getKeyCode() == KeyEvent.VK_S){
	    		planePoint.y += 10;	    	
	    	}if(e.getKeyCode() == KeyEvent.VK_A){
		   		planePoint.x -= 10;
	    	}if(e.getKeyCode() == KeyEvent.VK_D){
	    		planePoint.x += 10;
	    	}
		}catch(NullPointerException ex) {
    		ex.printStackTrace();
    	}
	   	repaint();
	}
	
	/*初始化坐标*/
	//背景坐标
	Point bgPoint = new Point(0, 0);
	//飞机坐标
	Point planePoint = new Point(270, 550);
	//启动线程
	public PlaneGameClassOne() {
		new Thread(new BgThread()).start();
	}
	@Override
	public void paint(Graphics g){
		//重叠
		super.paint(g);
		
		//创建一个绘制容器
		BufferedImage image = new BufferedImage(640, 700, BufferedImage.TYPE_INT_RGB);
		//创建一个画笔
		Graphics2D gs = image.createGraphics();
		//绘制背景
		gs.drawImage(PlaneGame.maps1.get("city.jpg"), bgPoint.x, bgPoint.y, this);
		gs.drawImage(PlaneGame.maps1.get("city.jpg"), bgPoint.x, bgPoint.y-715, this);
		//绘制飞机
		gs.drawImage(PlaneGame.maps1.get("plane.jpg"), planePoint.x, planePoint.y, this);
		
		//更新画板
		g.drawImage(image, 0, 0, this);
		
	}
	class BgThread implements Runnable{
	
	    @Override
	    public void run() {
		    while (true) {
		    	if(bgPoint.y == 700) {
		    		bgPoint.y = -15;
		    	}
		    	bgPoint.y += 1;
		    	try {
		    		Thread.sleep(10);
				} catch(InterruptedException ex) {
				    Thread.currentThread().interrupt();
			   	}
			    repaint();
		    }
	    }
    }
}

异常:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
	at indi.fishing.PlaneGame.PlaneGamev1.PlaneGame$KeyListener.keyPressed(PlaneGame.java:73)
	at java.awt.Component.processKeyEvent(Component.java:6491)
	at java.awt.Component.processEvent(Component.java:6310)
	at java.awt.Container.processEvent(Container.java:2236)
	at java.awt.Window.processEvent(Window.java:2025)
	at java.awt.Component.dispatchEventImpl(Component.java:4889)
	at java.awt.Container.dispatchEventImpl(Container.java:2294)
	at java.awt.Window.dispatchEventImpl(Window.java:2746)
	at java.awt.Component.dispatchEvent(Component.java:4711)
	at java.awt.KeyboardFocusManager.redispatchEvent(KeyboardFocusManager.java:1954)
	at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(DefaultKeyboardFocusManager.java:806)
	at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(DefaultKeyboardFocusManager.java:1074)
	at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(DefaultKeyboardFocusManager.java:945)
	at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:771)
	at java.awt.Component.dispatchEventImpl(Component.java:4760)
	at java.awt.Container.dispatchEventImpl(Container.java:2294)
	at java.awt.Window.dispatchEventImpl(Window.java:2746)
	at java.awt.Component.dispatchEvent(Component.java:4711)
	at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
	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:80)
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:90)
	at java.awt.EventQueue$4.run(EventQueue.java:731)
	at java.awt.EventQueue$4.run(EventQueue.java:729)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
	at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
	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)

[FishingProgrammer]

图片都有的,但是一按键盘就报一遍错