String immutable? 2

[chrissie1]

In .net a string is immutable is it the same for java and how to concat the correct way?

Christiaan Baes
Belgium

I just like this --> [Wiggle] [Wiggle]

 

[Diancecht]

Yes, it is:

http://www.programmersheaven.com/2/FAQ-JAVA-String-Is-Immutable

Simplest way to concat two Strings:

String one = "0ne";
String two = "two";
String oneplustwo = one + two;

Another way

String one = "0ne";
String two = "two";
String oneplustwo = one.concat(two);

The rigth way (performace issue)

String one = "0ne";
String two = "two";
StringBuffer oneplustwo = new StringBuffer(6);
oneplustwo.append(one);
oneplustwo.append(two);
String myFinalString = oneplustwo.toString();

Cheers,
Dian

 

[chrissie1]

Thanks.

Christiaan Baes
Belgium

I just like this --> [Wiggle] [Wiggle]

 

[sedj]

I would always use Dian's method one - its just the easiest and there are no problems doing it.

Similarly, if you have a primitive (int, double, char etc) that you want to convert to a String the easiest way is :

int i = 5;
String s = i +"";

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[chrissie1]

Yep, but like in .net, won't it create an overhead for example
forgive the syntax.

String oneplustwo;
oneplustwo += "one";
oneplustwo += " two";
oneplustwo += " three";
oneplustwo += " four";

would need 5 memoryallocations
while

StringBuffer oneplustwo = new StringBuffer(6);
oneplustwo.append("one");
oneplustwo.append("two");
oneplustwo.append("three");
oneplustwo.append("four");
String myFinalString = oneplustwo.toString();

this will only need two, give or take a one here and there.


Christiaan Baes
Belgium

I just like this --> [Wiggle] [Wiggle]

 

[sedj]

If you are appending lots of Strings, or several alrge Strings then a StringBuffer is the right approach.
But if its just something like :

String server = "localhost";
String port = "8080";
String serverPort = server +":" +port;

then I wouldn't other using a StringBuffer - you just won't see an overhead or differrence in such a case.


--------------------------------------------------
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http://www.primrose.org.uk

 

[chrissie1]

I understand, thanks.

Christiaan Baes
Belgium

I just like this --> [Wiggle] [Wiggle]

 

[Diancecht]

Just in case you want to get a deep breath

http://www.javaspecialists.co.za/archive/Issue068.html

Cheers,
Dian

 

[chrissie1]

Very interesting, thanks.

Christiaan Baes
Belgium

I just like this --> [Wiggle] [Wiggle]