title: Merged 2 PDF files to a new file
body: <p>I have 2 PDF files.</p>
  
  <p>I read both files as byte arrays, <code>file1</code> and <code>file2</code>, and concatenate then to a third array <code>file3</code>.  </p>
  
  <p>When I write this third array to the file system, the created file size is the sum of <code>file1</code> and <code>file2</code>, but it shows only the content of <code>file1</code>.</p>
  
  <p>Here is how I write the array to the file system:</p>
  
  <pre><code>try (FileOutputStream stream = new FileOutputStream(path)) {
      stream.write(file3);
  }
  </code></pre>
  
  <p>How can i see all pages of merged file ?</p>