java.lang.IllegalArgumentException: input == null

Question

I'm participating in this Mini Ludum Dare #49

I've got my code done but I've got one problem (well a few) when running and compiling.

I am getting this output in the console "

java.lang.IllegalArgumentException: input == null!
    at javax.imageio.ImageIO.read(Unknown Source)
    at com.cmnatic.mld.GameState.IntroState.init(IntroState.java:31)
    at com.cmnatic.mld.Manager.GameStateManager.setState(GameStateManager.java:46)
    at com.cmnatic.mld.Manager.GameStateManager.<init>(GameStateManager.java:36)
    at com.cmnatic.mld.Main.GamePanel.init(GamePanel.java:95)
    at com.cmnatic.mld.Main.GamePanel.run(GamePanel.java:59)
    at java.lang.Thread.run(Unknown Source)

" Now, I can give a long list of all the class files' code.

(com.cmnatic.mld.GameState.IntroState) at com.cmnatic.mld.GameState.IntroState.init(IntroState.java:31))

import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;

import javax.imageio.ImageIO;

import com.cmnatic.mld.Main.GamePanel;
import com.cmnatic.mld.Manager.GameStateManager;
import com.cmnatic.mld.Manager.Keys;

public class IntroState extends GameState {

    private BufferedImage logo;

    private int alpha;
    private int ticks;

    private final int FADE_IN = 60;
    private final int LENGTH = 60;
    private final int FADE_OUT = 60;

    public IntroState(GameStateManager gsm) {
        super(gsm);
    }

    public void init() {
        ticks = 0;
        try {
            logo = ImageIO.read(getClass().getResourceAsStream("res/Logo/logo.gif"));
        }
        catch(Exception e) {
            e.printStackTrace();
        }
    }

    public void update() {
        handleInput();
        ticks++;
        if(ticks < FADE_IN) {
            alpha = (int) (255 - 255 * (1.0 * ticks / FADE_IN));
            if(alpha < 0) alpha = 0;
        }
        if(ticks > FADE_IN + LENGTH) {
            alpha = (int) (255 * (1.0 * ticks - FADE_IN - LENGTH) / FADE_OUT);
            if(alpha > 255) alpha = 255;
        }
        if(ticks > FADE_IN + LENGTH + FADE_OUT) {
            gsm.setState(GameStateManager.MENU);
        }
    }

    public void draw(Graphics2D g) {
        g.setColor(Color.WHITE);
        g.fillRect(0, 0, GamePanel.WIDTH, GamePanel.HEIGHT2);
        g.drawImage(logo, 0, 0, GamePanel.WIDTH, GamePanel.HEIGHT2, null);
        g.setColor(new Color(0, 0, 0, alpha));
        g.fillRect(0, 0, GamePanel.WIDTH, GamePanel.HEIGHT2);
    }

    public void handleInput() {
        if(Keys.isPressed(Keys.ENTER)) {
            gsm.setState(GameStateManager.MENU);
        }
    }

}

(at com.cmnatic.mld.Manager.GameStateManager.setState(GameStateManager.java:46) at com.cmnatic.mld.Manager.GameStateManager.(GameStateManager.java:36)

package com.cmnatic.mld.GameState;

import java.awt.Graphics2D;

import com.cmnatic.mld.Manager.GameStateManager;

import java.awt.Graphics2D;


public abstract class GameState {

    protected GameStateManager gsm;

    public GameState(GameStateManager gsm) {
        this.gsm = gsm;
    }

    public abstract void init();
    public abstract void update();
    public abstract void draw(Graphics2D g);
    public abstract void handleInput();

}

at com.cmnatic.mld.Main.GamePanel.init(GamePanel.java:95) at com.cmnatic.mld.Main.GamePanel.run(GamePanel.java:59)

package com.cmnatic.mld.Main;

import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.image.BufferedImage;

import javax.swing.JPanel;

import com.cmnatic.mld.Manager.GameStateManager;
import com.cmnatic.mld.Manager.Keys;

@SuppressWarnings("serial")
public class GamePanel extends JPanel implements Runnable, KeyListener {

    // dimensions
    // HEIGHT is the playing area size
    // HEIGHT2 includes the bottom window
    public static final int WIDTH = 128;
    public static final int HEIGHT = 128;
    public static final int HEIGHT2 = HEIGHT + 16;
    public static final int SCALE = 3;

    // game loop stuff
    private Thread thread;
    private boolean running;
    private final int FPS = 30;
    private final int TARGET_TIME = 1000 / FPS;

    // drawing stuff
    private BufferedImage image;
    private Graphics2D g;

    // game state manager
    private GameStateManager gsm;

    // constructor
    public GamePanel() {
        setPreferredSize(new Dimension(WIDTH * SCALE, HEIGHT2 * SCALE));
        setFocusable(true);
        requestFocus();
    }

    // ready to display
    public void addNotify() {
        super.addNotify();
        if(thread == null) {
            addKeyListener(this);
            thread = new Thread(this);
            thread.start();
        }
    }

    // run new thread
    public void run() {

        init();

        long start;
        long elapsed;
        long wait;

        // game loop
        while(running) {

            start = System.nanoTime();

            update();
            draw();
            drawToScreen();

            elapsed = System.nanoTime() - start;

            wait = TARGET_TIME - elapsed / 1000000;
            if(wait < 0) wait = TARGET_TIME;

            try {
                Thread.sleep(wait);
            }
            catch(Exception e) {
                e.printStackTrace();
            }

        }

    }

    // initializes fields
    private void init() {
        running = true;
        image = new BufferedImage(WIDTH, HEIGHT2, 1);
        g = (Graphics2D) image.getGraphics();
        gsm = new GameStateManager();
    }

    // updates game
    private void update() {
        gsm.update();
        Keys.update();
    }

    // draws game
    private void draw() {
        gsm.draw(g);
    }

    // copy buffer to screen
    private void drawToScreen() {
        Graphics g2 = getGraphics();
        g2.drawImage(image, 0, 0, WIDTH * SCALE, HEIGHT2 * SCALE, null);
        g2.dispose();
    }

    // key event
    public void keyTyped(KeyEvent key) {}
    public void keyPressed(KeyEvent key) {
        Keys.keySet(key.getKeyCode(), true);
    }
    public void keyReleased(KeyEvent key) {
        Keys.keySet(key.getKeyCode(), false);
    }

}

at java.lang.Thread.run(Unknown Source)

Sorry for the really long post, but that's the code that's related to the problem.

I'm really tired so I'll sleep for a few hours and check back :)

Thanks guys,

Answer 1

Supposing you have the following folder structure (use the lowercase convention)

project
  | -- src
  | -- resources
  |       | -- logo
  |             | -- logo.gif

modify your IntroState.init() to

try {
    logo = ImageIO.read(getClass().getResource("/resources/logo/logo.gif"));
}

Note the / before resources . This code works perfectly. Just tested with a simple application.

Answer 2

The problem is that getClass().getResourceAsStream("res/Logo/logo.gif") returns null . So, when you pass it as the first argument of ImageIO.read() , it will throw an IllegalArgumentException , as said in ImageIO javadoc :

Throws:

 IllegalArgumentException - if input is null. 

According to the Class javadoc , getResourceAsStream() returns null when it can't find the ressource:

Returns:

 A InputStream object or null if no resource with this name is found 

So, the problem is that res/Logo/logo.gif cannot be found.

Here is what you have to check:

• does the file exists ?
• is it the correct path ?
• is the case correct ?
• do you miss a "/" at the beginning of the path (thus making it relative instead of absolute) ?

Answer 3

Okay, 3 years to late, but I got the same problem and also none of the answers worked. So I tried this and now it's working fine (so if anyone is searching for this):

Refresh the resouces folder in the Eclipse package explorer!

Now the image should show up in the explorer and then there is no more exception.