Difference between Initializing string with new and “ ”

Question

Which one is correct and why:

String dynamic = new String();
dynamic = \" where id=\'\" + unitId + \"\'\";

Or

String dynamic = \" where id=\'\" + unitId + \"         


        

Answer 1

I would suggest you to do in this way

String dynamic = " where id='" + unitId + "'";

String dynamic  = new String();// DON'T DO THIS!
dynamic = " where id='" + unitId + "'";

The statement creates a new String instance each time it is executed, and none of those object creations is necessary. The argument to the String constructor (" where id='" + unitId + "'") is itself a String instance, functionally identical to all of the objects created by the constructor. If this usage occurs in a loop or in a frequently invoked method, millions of String instances can be created needlessly. The improved version is simply the following:

String dynamic = " where id='" + unitId + "'";