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POBest practices/performance: mixing StringBuilder.append with String.concat
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copied!<p>I'm trying to understand what the best practice is and why for concatenating string literals and variables for different cases. For instance, if I have code like this</p> <pre><code>StringBuilder sb = new StringBuilder("AAAAAAAAAAAAA") .append(B_String).append("CCCCCCCCCCC").append(D_String) .append("EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE") .append("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF"); </code></pre> <p>Is this the way to do it? From <a href="https://stackoverflow.com/questions/47605/java-string-concatenation">this post</a>, I noticed that the <code>+</code> operator on Strings creates a new instance of StringBuilder, concatenates the operands, and returns a String conversion, which seems like a lot more work than just calling <code>.append()</code>; so if that's true, then that is out of the question. But what about <code>String.concat()</code>? Is it proper to use <code>.append()</code> for every concatenation? Or just for variables, and literals are okay to append with <code>.concat()</code>?</p> <pre><code>StringBuilder sb = new StringBuilder("AAAAAAAAAAAAA") .append(B_String.concat("CCCCCCCCCCC")).append(D_String .concat("EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE") .concat("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF")); </code></pre> <p>What are the general rules for best practices and performance for going about these situations? Is my assumption correct on <code>+</code> and it should really just not be used?</p>

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