这是一个Applet 游戏。我想让它成为一个应用程序。所以我在我的 StartingClass 中扩展了 JPanel。这是有效的，但是当从 start() 方法调用 loadMap() 方法时，map 不会加载。 map 实际上是一个文本文件。但这并没有加载。谁能帮我解决这个问题吗？
起始类(class):
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.image.BufferedImage;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import javax.imageio.ImageIO;
import javax.swing.JPanel;
public class StartingClass extends JPanel implements Runnable, KeyListener {
// enum GameState {
// Running, Dead
// }
//
// GameState state = GameState.Running;
private static final int Running = 1;
private static final int Dead = 2;
private static int state = Running;
private static Robot robot;
public static Heliboy hb, hb2;
public static int score = 0;
private Font font = new Font(null, Font.BOLD, 30);
private static Background bg1, bg2;
private BufferedImage image, currentSprite, character, character2,
character3, characterDown, characterJumped, background, heliboy,
heliboy2, heliboy3, heliboy4, heliboy5;
private Graphics second;
private Animation anim, hanim;
public static Image tilegrassTop, tilegrassBot, tilegrassLeft,
tilegrassRight, tiledirt;
private ArrayList<Tile> tilearray = new ArrayList<Tile>();
public void init() {
setSize(800, 480);
setBackground(Color.BLACK);
setFocusable(true);
addKeyListener(this);
try {
character = ImageIO.read(this.getClass().getResource(
"data/character.png"));
character2 = ImageIO.read(this.getClass().getResource(
"data/character2.png"));
character3 = ImageIO.read(this.getClass().getResource(
"data/character3.png"));
characterDown = ImageIO.read(this.getClass().getResource(
"data/down.png"));
characterJumped = ImageIO.read(this.getClass().getResource(
"data/jumped.png"));
heliboy = ImageIO.read(this.getClass().getResource(
"data/heliboy.png"));
heliboy2 = ImageIO.read(this.getClass().getResource(
"data/heliboy2.png"));
heliboy3 = ImageIO.read(this.getClass().getResource(
"data/heliboy3.png"));
heliboy4 = ImageIO.read(this.getClass().getResource(
"data/heliboy4.png"));
heliboy5 = ImageIO.read(this.getClass().getResource(
"data/heliboy5.png"));
background = ImageIO.read(this.getClass().getResource(
"data/background.png"));
tiledirt = ImageIO.read(this.getClass().getResource(
"data/tiledirt.png"));
tilegrassTop = ImageIO.read(this.getClass().getResource(
"data/tilegrasstop.png"));
tilegrassBot = ImageIO.read(this.getClass().getResource(
"data/tilegrassbot.png"));
tilegrassLeft = ImageIO.read(this.getClass().getResource(
"data/tilegrassleft.png"));
tilegrassRight = ImageIO.read(this.getClass().getResource(
"data/tilegrassright.png"));
} catch (Exception e) {
}
anim = new Animation();
anim.addFrame(character, 1250);
anim.addFrame(character2, 50);
anim.addFrame(character3, 50);
anim.addFrame(character2, 50);
hanim = new Animation();
hanim.addFrame(heliboy, 100);
hanim.addFrame(heliboy2, 100);
hanim.addFrame(heliboy3, 100);
hanim.addFrame(heliboy4, 100);
hanim.addFrame(heliboy5, 100);
hanim.addFrame(heliboy4, 100);
hanim.addFrame(heliboy3, 100);
hanim.addFrame(heliboy2, 100);
currentSprite = anim.getImage();
}
public void start() {
bg1 = new Background(0, 0);
bg2 = new Background(2160, 0);
robot = new Robot();
hb = new Heliboy(340, 360);
hb2 = new Heliboy(700, 360);
// Initialize tiles
try {
loadMap("data/map1.txt"); //What is the problem here??
System.out.print("Pobon File Inside");
} catch (Exception e) {
// TODO: handle exception
}
Thread thread = new Thread(this);
thread.start();
}
// Loading the tile map
private void loadMap(String filename) throws IOException {
ArrayList lines = new ArrayList();
int width = 0;
int height = 0;
FileReader fReader = new FileReader(filename);
BufferedReader reader = new BufferedReader(fReader);
while (true) {
String line = reader.readLine();
if (line == null) {
reader.close();
break;
}
if (!line.startsWith("!")) {
lines.add(line);
width = Math.max(width, line.length());
}
}
height = lines.size(); // it represents the total arraylist value size
for (int j = 0; j < 12; j++) {
String line = (String) lines.get(j);
for (int i = 0; i < width; i++) {
System.out.println(i + " is i");
if (i < line.length()) {
char ch = line.charAt(i);
Tile t = new Tile(i, j, Character.getNumericValue(ch));
tilearray.add(t);
}
}
}
}
@Override
public void run() {
if (state == Running) {
while (true) {
robot.update();
if (robot.isJumped() == true) {
robot.setDucked(false);
currentSprite = characterJumped;
} else if (robot.isJumped() == false) {
currentSprite = anim.getImage();
}
if (robot.isDucked() == true) {
currentSprite = characterDown;
}
ArrayList<Projectile> projectiles = robot.getProjectiles();
for (int i = 0; i < projectiles.size(); i++) {
Projectile p = (Projectile) projectiles.get(i);
if (p.isVisible() == true) {
p.update();
} else {
projectiles.remove(i);
}
}
updateTiles();
hb.update();
hb2.update();
bg1.update();
bg2.update();
animate();
repaint();
System.out.print("Pobon run");
try {
Thread.sleep(17);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
if (robot.getCenterY() > 500) {
state = Dead;
}
}
}
}
public void animate() {
anim.update(10);
hanim.update(50);
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
if (state == Running) { // set for game state Running
g.drawImage(background, bg1.getBgX(), bg1.getBgY(), this); // This is line `242`
g.drawImage(background, bg2.getBgX(), bg2.getBgY(), this);
paintTiles(g);
g.drawImage(currentSprite, robot.getCenterX() - 61,
robot.getCenterY() - 63, this);
g.drawImage(hanim.getImage(), hb.getCenterX() - 48,
hb.getCenterY() - 48, this);
g.drawImage(hanim.getImage(), hb2.getCenterX() - 48,
hb2.getCenterY() - 48, this);
ArrayList<Projectile> projectiles = robot.getProjectiles();
for (int i = 0; i < projectiles.size(); i++) {
Projectile p = (Projectile) projectiles.get(i);
g.setColor(Color.YELLOW);
g.fillRect(p.getX(), p.getY(), 10, 5);
}
g.setFont(font);
g.setColor(Color.WHITE);
g.drawString("Score: " + Integer.toString(score), 640, 30);
// Set for Enemy Health
if (hb.enemyVisibility == true) {
g.drawString("Health: " + Integer.toString(hb.health), 450, 30);
} else if (hb2.enemyVisibility == true) {
g.drawString("Health: " + Integer.toString(hb2.health), 450, 30);
}
} else if (state == Dead) { // set for game state Dead
g.setColor(Color.BLACK);
g.fillRect(0, 0, 800, 480);
g.setFont(new Font("SansSerif", Font.BOLD, 60));
g.setColor(Color.WHITE);
g.drawString("DEAD", 310, 240);
}
}
private void updateTiles() {
for (int i = 0; i < tilearray.size(); i++) {
Tile t = (Tile) tilearray.get(i);
t.update();
}
}
private void paintTiles(Graphics g) {
for (int i = 0; i < tilearray.size(); i++) {
Tile t = (Tile) tilearray.get(i);
g.drawImage(t.getTileImage(), t.getTileX(), t.getTileY(), this);
}
}
@Override
public void keyPressed(KeyEvent e) {
switch (e.getKeyCode()) {
case KeyEvent.VK_UP:
System.out.println("moving up");
break;
case KeyEvent.VK_DOWN:
if (robot.isJumped() == false) {
// currentSprite = anim.getImage();
robot.setDucked(true);
robot.setSpeedX(0);
}
break;
case KeyEvent.VK_LEFT:
robot.moveLeft();
robot.setMovingLeft(true);
break;
case KeyEvent.VK_RIGHT:
robot.moveRight();
robot.setMovingRight(true);
break;
case KeyEvent.VK_SPACE:
robot.jump();
break;
case KeyEvent.VK_CONTROL:
if (robot.isDucked() == false && robot.isJumped() == false) {
robot.shoot();
robot.setReadyToFire(false);
}
break;
}
}
@Override
public void keyReleased(KeyEvent e) {
switch (e.getKeyCode()) {
case KeyEvent.VK_UP:
System.out.println("stop moving up");
break;
case KeyEvent.VK_DOWN:
currentSprite = character;
robot.setDucked(false);
break;
case KeyEvent.VK_LEFT:
robot.stopLeft();
break;
case KeyEvent.VK_RIGHT:
robot.stopRight();
break;
case KeyEvent.VK_SPACE:
break;
case KeyEvent.VK_CONTROL:
robot.setReadyToFire(true);
break;
}
}
@Override
public void keyTyped(KeyEvent e) {
// TODO Auto-generated method stub
}
public static Background getBg1() {
return bg1;
}
public static Background getBg2() {
return bg2;
}
public static Robot getRobot() {
return robot;
}
}
主类:
import java.awt.BorderLayout;
import javax.swing.JFrame;
public class MainClass {
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
frame.setSize(800, 480);
frame.setResizable(false);
frame.setLocationRelativeTo(null);
StartingClass startingClass = new StartingClass();
startingClass.init();
startingClass.start();
frame.add(startingClass, BorderLayout.CENTER);
}
}
StackTrace 显示的是:
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at StartingClass.paintComponent(StartingClass.java:242)
at javax.swing.JComponent.paint(Unknown Source)
at javax.swing.JComponent.paintChildren(Unknown Source)
at javax.swing.JComponent.paint(Unknown Source)
at javax.swing.JComponent.paintChildren(Unknown Source)
at javax.swing.JComponent.paint(Unknown Source)
at javax.swing.JLayeredPane.paint(Unknown Source)
at javax.swing.JComponent.paintChildren(Unknown Source)
at javax.swing.JComponent.paintToOffscreen(Unknown Source)
at javax.swing.RepaintManager$PaintManager.paintDoubleBuffered(Unknown Source)
at javax.swing.RepaintManager$PaintManager.paint(Unknown Source)
at javax.swing.RepaintManager.paint(Unknown Source)
at javax.swing.JComponent.paint(Unknown Source)
at java.awt.GraphicsCallback$PaintCallback.run(Unknown Source)
at sun.awt.SunGraphicsCallback.runOneComponent(Unknown Source)
at sun.awt.SunGraphicsCallback.runComponents(Unknown Source)
at java.awt.Container.paint(Unknown Source)
at java.awt.Window.paint(Unknown Source)
at javax.swing.RepaintManager$3.run(Unknown Source)
at javax.swing.RepaintManager$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at javax.swing.RepaintManager.paintDirtyRegions(Unknown Source)
at javax.swing.RepaintManager.paintDirtyRegions(Unknown Source)
at javax.swing.RepaintManager.prePaintDirtyRegions(Unknown Source)
at javax.swing.RepaintManager.access$1100(Unknown Source)
at javax.swing.RepaintManager$ProcessingRunnable.run(Unknown Source)
at java.awt.event.InvocationEvent.dispatch(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$200(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
最佳答案
swing 使用 paintComponent 方法来绘制内容，并且在 start 方法中初始化 bg1 和 bg2 之前调用此方法。
一个简单的解决方法是引入一个附加状态:
private static final int Initializing = 0;
private static int state = Initializing;
在启动方法中将状态更新为Running:
public void start() {
bg1 = new Background(0, 0);
bg2 = new Background(2160, 0);
robot = new Robot();
hb = new Heliboy(340, 360);
hb2 = new Heliboy(700, 360);
state = Running;
...
关于java - 谁能帮我使用 StartingClass 中的 loadMap() 方法加载 map (文本文件)？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/34220489/