Syntax error--passing "double" as primitive type to map
<p>So I found source code that presumably parses a mathematical expression and calculates the answer.  However, the code contains a syntax error when declaring a new map.  This new map is supposed to hold a String and a number.  I do know that maps can't reference primitive types, like double, though.  How can I resolve this issue?</p>

<pre><code>private Map&lt;String, double=""&gt; user_var = new HashMap&lt;String, double=""&gt;();
</code></pre>

<p>To see the rest of the code, one can visit <a href="http://tapas4web.blogspot.com/2011/05/mathematical-expression-parser-in-java.html" rel="nofollow">here</a></p>

<p>Thank you</p>
