我的代码出现问题。我刚开始使用Eclipse。现在,我正在使用Java进行平台游戏。我遇到了Homestuck代码问题。这是在public static void main(String [] args)之下。谢谢你的帮助!
错误:
Exception in thread "main" java.lang.IllegalArgumentException: input == null!
at javax.imageio.ImageIO.read(ImageIO.java:1388)
at projectOne.<init>(projectOne.java:31)
at projectOne.main(projectOne.java:104)
代码:
import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.*;
public class projectOne extends JPanel
{
/**
*
*/
private static final long serialVersionUID = 1L;
GameEvents gameEvents = new GameEvents();
Timer gameTimer = new Timer(1, gameEvents);
int i = 0;
int horizontalposition = 500;
int verticalposition = 500;
BufferedImage Picture;
//Don't forget to declare your variables!
projectOne()
{
gameTimer.start();
this.addKeyListener(gameEvents);
try
{
Picture = ImageIO.read(getClass().getResource("Homestuck.gif"));
//The format for this is Picture = ImageIO.read(getClass().getResource("NameOfFile.typeoffile"));
}
catch (IOException e)
{
System.out.println("Pictures failed to load");
}
}
@Override
protected void paintComponent(Graphics g)
{
g.setColor(Color.blue);
g.fillRect(0,0,this.getWidth(), this.getHeight());
g.setColor(Color.red);
///g.drawImage(Picture, horizontalposition, verticalposition, 100, 150, null);
g.drawImage(Picture, 50, 100, 500, 600, null);
//Here's the format you must follow when drawing simple Java Graphics objects
//g.fillOval(horizontal location, vertical location, width, height)
}
public class GameEvents implements ActionListener, KeyListener
{
@Override
public void actionPerformed(ActionEvent arg0)
{
repaint();
}
@Override
public void keyPressed(KeyEvent key) //stuff inside here happens when a key is pressed
{
if(key.getKeyChar()=='d')
{
horizontalposition=horizontalposition+20;
}
if(key.getKeyChar()=='s')
{
verticalposition=verticalposition+20;
}
if(key.getKeyChar()=='w')
{
verticalposition=verticalposition-20;
}
if(key.getKeyChar()=='a')
{
horizontalposition=horizontalposition-20;
}
if(horizontalposition<0)
{
horizontalposition=0;
}
System.out.println(key.getKeyChar());
System.out.println('d');
}
@Override
public void keyReleased(KeyEvent arg0) {
}
@Override
public void keyTyped(KeyEvent arg0) {
}
}
public static void main(String[] args)
{
JFrame f = new JFrame("Java Graphics Example Project");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
projectOne p = new projectOne();
f.setSize(1500,700);
f.add(p);
f.setVisible(true);
p.requestFocusInWindow();
}
}
答案 0 :(得分:1)
在这一行
Picture = ImageIO.read(getClass().getResource("Homestuck.gif"));
getResource调用必须返回null。我建议将其隔离为局部变量,以便于调试:
File imageFile = getClass().getResource("Homestuck.gif");
if (imageFile == null) {
//consider throwing an exception here
} else {
Picture = ImageIO.read(imageFile);
}
答案 1 :(得分:1)
试试这个,使用ResourceAsStream:
Picture = ImageIO.read(this.getClass().getResourceAsStream("Homestuck.gif"));