Read hidden zip file

I have a jpeg, and on the end of it I wrote a zip file.

Inside this zip file is a single txt file called hidden.txt. I can change the extension to zip and read the file just fine on my laptop (debian) but when I try to read it using either a ZipInputStream or using ZipFile I get an error telling me it's not a zip file.

I tried separating the jpg part out first by reading the whole thing to a Bitmap then writing that to a byte[], however the byte[] encompassed more than just the image.

My method to combine the bitmap and the zipFile (a byte[])

private byte[] combineFiles(Bitmap drawn, byte[] zip) throws
        IOException {
    InputStream in;
    ByteArrayOutputStream out = new ByteArrayOutputStream();

    /*write the first file*/
    byte[] img;
    ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
    drawn.compress(Bitmap.CompressFormat.JPEG, 100, byteArrayOutputStream);
    img = byteArrayOutputStream.toByteArray();
    in = new ByteArrayInputStream(img);
    IOUtils.copy(in, out);
    in.close();

    /*add the second (hidden) file*/
    in = new ByteArrayInputStream(zip);

    IOUtils.copy(in, out);
    out.flush();
    in.close();
    return out.toByteArray();
}

So really I have two questions,

1. How do I separate the jpg and zip portions of the file?


2. How do I unzip hidden.txt (preferably into a byte[])
   
   
   
   • fairly certain I know this one, but what I am doing currently does not work, probably because I am doing #1 wrong