Java syntax: When declaring a string, what is the purpose of the new keyword in front of the string instead of just simply assigning it.
Example:
String str = new String ("Welcome!");
String strTwo = "Welcome!";
What is the difference?
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kalenpw
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Steven Levine
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1The first example creates a new string. The second uses the string literal pool. You should almost always opt for the second way. – shmosel Mar 15 '17 at 00:53
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also, by using new, you've actually done both, declared a literal and used new String() to make a new string based on that literal. – slipperyseal Mar 15 '17 at 00:56
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Please delete your question. – Derrops Mar 15 '17 at 00:59
1 Answers
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new String ("Welcome!") allocates a new string that's a copy of the given string.
This is almost never useful since Java strings are immutable.
The one case where it makes a difference is the new string will not be == to the given string. You should compare strings with .equals() in the first place.
Note that Java string literals are interned into a table of all the string literals. That way they share storage. It also makes == work for two string literals, but again you should only do that in very special cases.
Mostly, I think programmers coming from C++ use new because there it's needed to convert a C string literal into a std::string object.
Jerry101
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1as a side note, a String actually consists of a String container object and a private char[] which contains the characters. When you use the copy constructor, it will create a new String object but internally reference the same char array. this can be done safely as String are immutable. – slipperyseal Mar 15 '17 at 01:07