What's the difference b/w next() and hasNext()?

[jamesgo]

if the query has only one match, will hasNext() return true?

[Brad Tilton]

hasNext() either returns true or false while next() will actually iterate to the record.

So I could do:

gr.query();

if (gr.next()) {

   gr.field = 'value';

   gr.update();

}

but this won't update anything:

gr.query();

if (gr.hasNext()) {

   gr.field = 'value';

   gr.update();

}

So if there are one or more records contained in your gr set, hasNext() will return true.

[jamesgo]

Hi Brad, in 2nd scenario, gr doesn't iterate to the actual record? if there is only one match, what is contained in the gr when using hasNext?

[rmaroti]

When I was try with above code in nest() if I got the updated record but not updated in case of hasNext().

[asane]

Hey Brad, Very clear presentation via code; 
I like to add performance & business context to both hasNext() & next() methods
Performance: 
hasNext() : best - very efficient & light on system.
next(): Heavy on system.
Business Context: 
1. Do we have any p1 - Incident not resolved this morning - hasNext()
well, you are just looking for YES or NO answer, so that you can inform the team to prioritize p1.
2. who is working on the p1-incident - next()
you can get the Engineer details who is handling the situation.