producing an empty zip file java

Question

I'm currently writing a function what would create a zip file, which will be used in other functionality. Below it is my function's code:

public void createZip(){

        try{
            String outfile = this.filename + ".zip";
            //input file
            FileInputStream input = new FileInputStream(this.filename);
            //output file
            ZipOutputStream zip = new ZipOutputStream(new FileOutputStream(outfile));
            //name the file inside the zip file
            System.out.println(this.filename);
            zip.putNextEntry(new ZipEntry(this.filename));

            byte[] buffer = new byte[this.BUFFER];
            int len;
            //copy the file to the zip
            while((len= input.read(buffer)) > 0){
                System.out.println(len);
                zip.write(buffer, 0, len);
            }
            zip.closeEntry();
            zip.flush();
            input.close();
            zip.close();
            this.filename += ".zip";
        }
        catch(IOException e){
            e.printStackTrace();
        }

    }

I have tried to debug, but I couldn't find the source of this problem. The function runs without any further problems, but the zip file produced it is an empty one.

Answer 1

You must close the entry using ZipOutputStream#closeEntry() prior to closing the output stream, or the entry is never confirmed to have been written entirely.

Also, the name of the ZipEntry cannot be the entire path; i.e, it should be dog.png instead of C:\Users\Admin\Documents\dog.png. This issue will pass by without an exception, and will cause the data from the file to be compressed directly into the zip, rather than into the zip as a compressed file.