.equals and request.getparameter

[Rajesh Khan]

I wanted to know what would be the correct way of doing something like this

String string_= "";
string_ = request.getParameter("some_parameter");
  if(!string_.equals(""))
  {....}

since .getPArameter doesnt put "" if the parameter is not found

[Seetharaman Venkatasamy]

Rajesh Khan wrote:

String string_= "";
string_ = request.getParameter("some_parameter");
  if(!string_.equals(""))
  {....}

since .getPArameter doesnt put "" if the parameter is not found

Yes. if parameter returns null then you will be end up with an exception.
so you can do this

if(!"".equals(string_)) 

since equals method dont throw exception if the argument is null, instead it returns false.
or

 if(string_ != null && !string_.equals(""))

I always use later idiom. because some times you need to invoke a method on string_

[Rajesh Khan]

Thanks but it should be

if(string_ != null)
 {
    if(!string_.equals(""))
    {}
 }

[Matthew Brown]

Rajesh Khan wrote:Thanks but it should be

if(string_ != null)
 {
    if(!string_.equals(""))
    {}
 }

Seetharaman's version is fine. It's a very common idiom. The point of using if(string_ != null && !string_.equals("")) is that the expression "short-circuits". If the first part is false it doesn't bother calculating the second part. So you can be sure that if it reaches the second part string_ is definitely not null.