FileNotFound Exception with

I have the following code;

String files="";
for (int i=0; i<filelist.size()-1;i++)
{
    files=files+filelist.get(i).getPath()+", ";
}
files=files+filelist.get(filelist.size()-1).getPath();
System.out.println(files);
Process zipping=new ProcessBuilder(
           "C:/Program Files/7-Zip/7z.exe", "a", "-t7z", "C:/Users/Pc/dog/test", files).start();
OutputStream steam=zipping.getOutputStream();
DbxClientV2 client = new DbxClientV2(config, ACCESS_TOKEN);
FileInputStream in =new FileInputStream(new File("C:/Users/Pc/dog/test.7z"));
client.files.upload("/test.7z").

uploadAndFinish(in);

Which gives java.io.FileNotFoundException: C:\Users\Pc\dog\test.7z error.

In addition, though the archive file is created, it does not contain the given files, which are given as;

C:\Users\Pc\Documents\untitled3.png, C:\Users\Pc\Documents\untitled2.png