Java Strings: “String s = new String(”silly“);”

Question

I\'m a C++ guy learning Java. I\'m reading Effective Java and something confused me. It says never to write code like this:

String s = new String(\"silly\");         


        

Answer 1

Java creates a String object for each string literal you use in your code. Any time "" is used, it is the same as calling new String().

Strings are complex data that just "act" like primitive data. String literals are actually objects even though we pretend they're primitive literals, like 6, 6.0, 'c', etc. So the String "literal" "text" returns a new String object with value char[] value = {'t','e','x','t}. Therefore, calling

new String("text"); 

is actually akin to calling

new String(new String(new char[]{'t','e','x','t'}));

Hopefully from here, you can see why your textbook considers this redundant.

For reference, here is the implementation of String: http://www.docjar.com/html/api/java/lang/String.java.html

It's a fun read and might inspire some insight. It's also great for beginners to read and try to understand, as the code demonstrates very professional and convention-compliant code.

Another good reference is the Java tutorial on Strings: http://docs.oracle.com/javase/tutorial/java/data/strings.html