Null Strings

[GlynW]

I write software in many languages, and am just getting to grips with Java and Java Script. I know all the programming concepts, but it's just finding the matching keywords.

I want to know how to tell if a string is empty:

I've tried:
if (request.company_type.length > 1){
which is fine unless they type a space. is there a command to trim the string of spaces before I check the length property?

I'm basicly trying check if some fields on a web page have something valid! entered. but not spaces or nulls

Cheers

Glyn

 

[pipk]

The String class has a method called trim() that removes leading and trailing spaces.

 

[PureNSimple]

Hi,
Yes there is a method to trim Strings in java and that is
yourString = yourString.trim();

regards
PNS

 

[dendenners]

As far as I can see the only way to ensure the string is non-empty and not null is
if(myString!=null&&myString.trim().length()!=0)
because of course if the string is null, the trim() will give a null pointer exception

 

[wushutwist]

Note: Java and Javascript are not the same. They are not even remotely similar. So it makes a big difference between wheather you are using Java or Javascript.

Secondly, your statement should look like:

String company_info = request.getParameter("company_type");
if (company_info != null && company_info.trim().equals("")) {
  /* COMPANY INFO ENTERED */
}

Wushutwist

 

[Guest_imported]

GlynW (forgot to login Doh!)

wushutwist,
I know what you mean by Java and Javascript not being the same, but as a newbie to Java and Javascript, this is where I'm getting into trouble...

The really good example you gave, is that for Java or Javascript, as I was having problems using the .trim method

I've actually got round the problem... probably a bit long winded with the following:... Any comments on tidying..


function validatefields{
<!--- ****** CHECK COMPANY NAME ****** --->
if (!checkfield(request.company_name.value)){
alert(&quot;Company Name Not Entered&quot;
request.company_name.focus();
return false;
}
}

<!--- CHECK IF FIELD IS NOT EMPTY OR JUST SPACES --->
function checkfield(fieldname){
if (fieldname==&quot;&quot{
return false;
}else{
if (notspaces(fieldname)){
return true;
}
}
}

<!--- CHECK IF NOT JUST SPACES ENTERED INTO FIELD --->
function notspaces(tvar){
for (var i=0;i<tvar.length;i++){
tchar=tvar.substring(i,i+1)
if (tchar != &quot; &quot{
return true;
}
}
}



Cheers for the help everyone

Glyn

 

[wushutwist]

I see. I assumed you were using JAVA. I would suggest that you post any further JAVASCRIPT questions to the Javascript group. You will most likely get a better and faster response. Wushutwist