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From: Eric Sosman <esosman@comcast-dot-net.invalid>
Newsgroups: comp.lang.java.programmer
Subject: Re: is that possible to include a small PNG file as part of Java class?
Date: Mon, 23 Jun 2014 13:03:37 -0400
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On 6/23/2014 12:02 PM, www wrote:
> Hi:
>
> I have a simple Java class: Abc.java. The method within it needs to access a small PNG file(it's an icon picture). Right now, this picture file("abc.png") is located at nonsrc/icons/abc.png
>
> So this class is a bit pain. Abc.class won't work in the absence of abc.png. When I create an executable JAR, this is pain: always need to remember to include abc.png file inside it.
>
> I am wondering if there is a way that I can "convert" abc.png into some sort of Java code and I can put it in Abc.java. So Abc.class alone can perform the job, without the need of presence of abc.png. Is that possible?
>
> Hope I have explained my intention well.

     Martin Gregorie's response seems to be good advice.  However, if
you simply *must* incorporate your PNG image as a class, you could do
so with a big byte[] array:

	private static final byte[] PNG_BUFFER = {
	    (byte)0x89, 0x50, 0x4E, 0x47, ... };

	public static Image getMyPNG() {
	    return ImageIO.read(new ByteArrayInputStream(PNG_BUFFER));
	}

However, this approach will only work for fairly small images.  The
problem is that Java class files have no way to store an initialized
array: The byte[] array above actually compiles to the equivalent of

	private static final byte[] PNG_BUFFER = new byte[whatever];
	static {
	    PNG_BUFFER[0] = (byte)0x89;
	    PNG_BUFFER[1] = 0x50;
	    PNG_BUFFER[2] = 0x4E;
	    PNG_BUFFER[3] = 0x47;
	    ...
	}

... with about four or so bytecode instructions per array element.
At that rate of bloat, even a modest-sized image risks generating
more code than a Java method can hold.

     You might evade the limits by writing the initialization explicitly
and breaking it up into multiple methods:

	private static final byte[] PNG_BUFFER = new byte[whatever];
	static {
	    firstK();
	    secondK();
	    ...
	}

	private static void firstK() {
	    PNG_BUFFER[0] = (byte)0x89;
	    PNG_BUFFER[1] = 0x50;
	    PNG_BUFFER[2] = 0x4E;
	    PNG_BUFFER[3] = 0x47;
	    ...
	    PNG_BUFFER[1023] = whatever;
	}

	private static void secondK() {
	    PNG_BUFFER[1024] = whatever;
	    ...
	    PNG_BUFFER[2047] = whatever;
	}

	...

IMHO, no sane person would do this.

-- 
Eric Sosman
esosman@comcast-dot-net.invalid