Question

For the life of me, I can t understand why adding a concatenated string to the MainScreen is causing the BB simulator to throw an exception. If I run a VERY simple hello program with the following control, all is well:

RichTextField rtfHello = new RichTextField("Hello There !!!");        
add(rtfItemDescription);

But if I add a concatenated string, the entire app breaks:

String MyName = "John Doe";
RichTextField rtfHello = new RichTextField("Hello There !!!" + MyName);        
add(rtfItemDescription);

So what am I doing wrong? Why would the simulator throw an exception for the second example?

Answer 1

Not sure why it would blow up (but I m not a blackberry/java developer). Have you simply tried:

String MyName = "John Doe"; 
String HelloString = "Hello There !!!";
RichTextField rtfHello = new RichTextField(HelloString.concat(MyName));         
add(rtfItemDescription);

Or simply,

String MyName = "John Doe"; 
RichTextField rtfHello = new RichTextField("Hello There!!!".concat(MyName));         
add(rtfItemDescription);

Answer 2

For string concatenations in Blackberry try to use StringBuffer class. StringBuffer is faster than String, because it mutable.

Answer 3

looks as that when i do any string concatenation in my blackberry project (using eclipse), the packaging process cannot find the definition of the class StringBuilder. the project is defaulted to jdk 1.4. StringBuilder wasn t introduced until version 1.5 so attempting to run the code will produce a "no class definition found" error message. So this is my guess as to why i am seeing my errors. – sexitrainer Jan 20 at 15:30

This is because StringBuilder is not a part of J2ME. You won t be able to use it while programming for mobile devices.

Answer 4

Try this

String MyName = "John Doe";
    RichTextField rtfHello = new RichTextField("Hello There !!!" + MyName);        
    add(rtfHello);

Answer 5

I don t think problem is with string concatenation. can provide more information like what exception you are getting.

友情链接