Question

I just stumbled upon this question Are "while(true)" loops so bad?

They made me think what do I normally do.And to my surprise I realised that I have almost never used a while loop in my professional code(or work code) .

Front end frameworks e.g faces etc do not count.

So When should I use a ‘while loop’? and
How often do you use while loop?
It’s is a real question please do not close as being subjective I really am after a concrete example.where it can not be replaced with a better alternate.

Answer 1

One place where I might use it is where you need to treat the first element of a sequence differently to the rest. That makes a foreach loop awkward, but a while loop works well:

Iterator<String> iterator = foo.iterator();

// Handle the first item specially
if (!iterator.hasNext()) {
    throw new SomeException("foo shouldn't be empty");
}
SomeResult result = new SomeResult(iterator.next());

// Now deal with the rest
while (iterator.hasNext())
{
    String item = iterator.next();
    result.addItem(item);
}

Also I use a while loop as one of the few places where I’ll also include an assignment in a condition:

String line;
while ((line = reader.readLine()) != null)
{
    // Handle the line
}

or with an InputStream:

int bytesRead;
while ((bytesRead = input.read(buffer)) != -1)
{
    // Handle the buffer
}