<!DOCTYPE qhelp PUBLIC

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<qhelp>

<overview>

<p>The <code>String</code> class is immutable, which means that there is

no way to change the string that it represents. Consequently, there is rarely a

need to copy a <code>String</code> object or construct a new instance based on

an existing string, for example by writing something like <code>String hello =

new String("hello")</code>. Furthermore, this practice is not memory efficient.</p>

</overview>

<recommendation>

<p>The copied string is functionally indistinguishable from the argument that

was passed into the <code>String</code> constructor, so you can simply omit the constructor call and

use the argument passed into it directly. Unless an explicit copy of the argument string is needed,

this is a safe transformation.</p>

</recommendation>

<example>

<p>The following example shows three cases of copying a string using the <code>String</code>

constructor, which is inefficient. In each case, simply removing the constructor call

<code>new String</code> and leaving the argument results in better code and less

memory churn.</p>

<sample src="NewStringString.java" />

</example>

<references>

<li>

J. Bloch, <em>Effective Java (second edition)</em>,

Item 5.

Addison-Wesley, 2008.

</li>

<li>

Java Platform, Standard Edition 6, API Specification:

<a href="http://docs.oracle.com/javase/6/docs/api/java/lang/String.html#String%28java.lang.String%29">String(String)</a>.

</li>

</references>

</qhelp>