Error In Java: IllegalArgumentException -

i working on game , getting error code:

exception in thread "main" java.lang.illegalargumentexception: input == null!     @ javax.imageio.imageio.read(unknown source)     @ com.mcserverpros.game.gfx.spritesheet.<init>(spritesheet.java:21)     @ com.mcserverpros.game.game.<init>(game.java:32)     @ com.mcserverpros.game.game.main(game.java:146) 

this game.java class:

package com.mcserverpros.game;  import java.awt.borderlayout; import java.awt.canvas; import java.awt.dimension; import java.awt.graphics; import java.awt.image.bufferstrategy; import java.awt.image.bufferedimage; import java.awt.image.databufferint;  import javax.swing.jframe;  import com.mcserverpros.game.gfx.spritesheet;  public class game extends canvas implements runnable {  private static final long serialversionuid = 1l;  public static final int width = 160; public static final int height = width / 12 * 9; public static final int scale = 3; public static final string name = "game";  private jframe frame;  public boolean running = false; public int tickcount = 0;  private bufferedimage image = new bufferedimage(width, height,         bufferedimage.type_int_rgb); private int[] pixels = ((databufferint) image.getraster().getdatabuffer())         .getdata();  public spritesheet spritesheet = new spritesheet("/sprite_sheet.png");  public game() {     setminimumsize(new dimension(width * scale, height * scale));     setmaximumsize(new dimension(width * scale, height * scale));     setpreferredsize(new dimension(width * scale, height * scale));      frame = new jframe(name);      frame.setdefaultcloseoperation(jframe.exit_on_close);     frame.setlayout(new borderlayout());      frame.add(this, borderlayout.center);     frame.pack();      frame.setresizable(false);     frame.setlocationrelativeto(null);     frame.setvisible(true);  }  public synchronized void start() {     running = true;     new thread(this).start();  }  public synchronized void stop() {     running = false; }  public void run() {     long lasttime = system.nanotime();     double nspertick = 1000000000d / 60d;      int frames = 0;     int ticks = 0;      long lasttimer = system.currenttimemillis();     double delta = 0;      while (running) {         long = system.nanotime();         delta += (now - lasttime) / nspertick;         lasttime = now;         boolean shouldrender = false;          while (delta >= 1) {             ticks++;             tick();             delta -= 1;             shouldrender = true;         }          try {             thread.sleep(2);         } catch (interruptedexception e) {             e.printstacktrace();         }          if (shouldrender) {             frames++;             render();         }          if (system.currenttimemillis() - lasttimer >= 1000) {             lasttimer += 1000;             system.out                     .println(ticks + " ticks" + ", " + frames + " frames");             frames = 0;             ticks = 0;          }     } }  public void tick() {     tickcount++;      (int = 0; < pixels.length; i++) {         pixels[i] = + tickcount;     } }  public void render() {     bufferstrategy bs = getbufferstrategy();     if (bs == null) {         createbufferstrategy(3);         return;     }      graphics g = bs.getdrawgraphics();     g.drawimage(image, 0, 0, getwidth(), getheight(), null);      g.dispose();     bs.show(); }  public static void main(string[] args) {     new game().start();  } } 

and spritesheet.java class

package com.mcserverpros.game.gfx;  import java.awt.image.bufferedimage; import java.io.ioexception;  import javax.imageio.imageio;  public class spritesheet { public string path; public int width; public int height;  public int[] pixels;  public spritesheet(string path) {     bufferedimage image = null;      try {         image = imageio.read(spritesheet.class.getresourceasstream(path));     } catch (ioexception e) {         e.printstacktrace();     }     if (image == null) {         return;     }     this.path = path;     this.width = image.getwidth();     this.height = image.getheight();      pixels = image.getrgb(0, 0, width, height, null, 0, width);      (int = 0; < pixels.length; i++) {         pixels[i] = (pixels[i] & 0xff) / 64;     }      (int = 0; < 8; i++) {         system.out.println(pixels[i]);     }  } } 

check line:

imageio.read(spritesheet.class.getresourceasstream(path)) 

it seems spritesheet.class.getresourceasstream(path) returning null value. it's quite possible path isn't pointing actual file in filesystem. notice you're passing "/sprite_sheet.png", that's path relative source code's directory. take @ this post idea of how can build relative path works. if else fails use absolute path, won't portable.