CreatesEmptyZip.qhelp

<!DOCTYPE qhelp PUBLIC
  "-//Semmle//qhelp//EN"
  "qhelp.dtd">
<qhelp>


<overview>
<p>The <code>ZipOutputStream</code> class is used to write ZIP files to a file
or other stream. A ZIP file consists of a number of <i>entries</i>. Usually
each entry corresponds to a file in the directory structure being zipped. There
is a method on <code>ZipOutputStream</code> that is slightly confusingly named 
<code>putNextEntry</code>. Despite its name, it does not write a whole entry.
Instead, it writes the <em>metadata</em> for an entry. The content for that entry
is then written using the <code>write</code> method. Finally the entry is
closed using <code>closeEntry</code>.</p>

<p>Therefore, if you call <code>putNextEntry</code> and <code>closeEntry</code> but omit the
call to <code>write</code>, an empty ZIP file entry is written to the output stream.</p>

</overview>
<recommendation>

<p>Ensure that you include a call to <code>ZipOutputStream.write</code>.</p>

</recommendation>
<example>

<p>In the following example, the <code>archive</code> method calls <code>putNextEntry</code> and
<code>closeEntry</code> but the call to <code>write</code> is left out.</p>

<sample src="CreatesEmptyZip.java" />

</example>
<references>


<li>
Java API Specification:
<a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/zip/ZipOutputStream.html">
ZipOutputStream</a>.
</li>


</references>
</qhelp>