What is the better approach to convert primitive data type into String
<p>I can convert an integer into string using</p>

<pre><code>String s = "" + 4; // correct, but poor style
or
String u = Integer.toString(4); // this is good
</code></pre>

<p>I can convert a double into string using</p>

<pre><code>String s = "" + 4.5; // correct, but poor style
or
String u = Double.toString(4.5); // this is good
</code></pre>

<p>I can use <code>String s = "" + data</code>approach to convert either an int or double into String. While If I wants to use the other approach using <code>toString()</code> I have to use the Wrapper class of each data type. Then why in <a href="http://ww0.java3.datastructures.net/contents/supplement2.pdf"><strong>some books</strong></a>  it is mentioned that the first approach is poor one while the second one is the better. <strong>Which one is the better approach and why?</strong></p>
