Styjun

The Ultimate Number Sequence Puzzle

Plausibility of squid whales

What happened in Rome, when the western empire "fell"?

Computationally populating tables with probability data

Inductor and Capacitor in Parallel

Audio Conversion With ADS1243

Can I board the first leg of the flight without having final country's visa?

What's the commands of Cisco query bgp neighbor table, bgp table and router table?

Does the Idaho Potato Commission associate potato skins with healthy eating?

What difference does it make using sed with/without whitespaces?

Where do students learn to solve polynomial equations these days?

Traveling with my 5 year old daughter (as the father) without the mother from Germany to Mexico

In the "Harry Potter and the Order of the Phoenix" video game, what potion is used to sabotage Umbridge's speakers?

What steps are necessary to read a Modern SSD in Medieval Europe?

Is French Guiana a (hard) EU border?

Man transported from Alternate World into ours by a Neutrino Detector

Cannot shrink btrfs filesystem although there is still data and metadata space left : ERROR: unable to resize '/home': No space left on device

TikZ: How to fill area with a special pattern?

Is Nisuin Biblical or Rabbinic?

What would be the main consequences for a country leaving the WTO?

Won the lottery - how do I keep the money?

Do I need to write [sic] when including a quotation with a number less than 10 that isn't written out?

Does Germany produce more waste than the US?

Why am I getting "Static method cannot be referenced from a non static context: String String.valueOf(Object)"?

Iterator for something generated recursively (without pre-generating the results)

1

I want to create an Iterator in Java (i.e. support hasNext() and next() calls). However, the thing I'm iterating is generated recursively. I want to be able to create this Iterator without having to generate the values beforehand and storing them. Instead, the next() call should get the next value that the recursion outputs, and hasNext() should check that the recursion is not yet done.

Is there a standard pattern for doing this?

Edit: I think a Python yield in a recursive function is the functionality I'm looking for. Not sure how to do it in Java though.

java recursion iterator iteration

share|improve this question

edited Mar 21 at 19:20

rococo

asked Mar 21 at 19:09

rococorococo

4511517

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Check out my code here. May be this is what you are looking for, if not then at least could offer some hints.
  
  – Rahul R.
  Mar 21 at 19:13
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Can you show an example of the recursive algorithm? Using iterators it's often possible to convert a recursive algorithm into an iterative one by retaining the state between calls to next().
  
  – Alnitak
  Mar 21 at 19:59
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I figured out an iterative solution to my specific problem: I was trying to generate all subsets of a certain size for a given set. I do this iteratively now by incrementing a set of indices on the original set. I'll leave the question open though, since I think there are definitely algorithms where it's difficult to get an iterative solution.
  
  – rococo
  Mar 21 at 20:31
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  See e.g.jdoodle.com/a/15tZ, where I've generated an O(1) algorithm using iterators to generate each member of the Fibonacci sequence.
  
  – Alnitak
  Mar 21 at 20:32
  
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  stackoverflow.com/questions/931762/…
  
  – Alnitak
  Mar 21 at 20:33
  

  
  
  
  

add a comment | 

1

I want to create an Iterator in Java (i.e. support hasNext() and next() calls). However, the thing I'm iterating is generated recursively. I want to be able to create this Iterator without having to generate the values beforehand and storing them. Instead, the next() call should get the next value that the recursion outputs, and hasNext() should check that the recursion is not yet done.

Is there a standard pattern for doing this?

Edit: I think a Python yield in a recursive function is the functionality I'm looking for. Not sure how to do it in Java though.

java recursion iterator iteration

share|improve this question

edited Mar 21 at 19:20

rococo

asked Mar 21 at 19:09

rococorococo

4511517

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Check out my code here. May be this is what you are looking for, if not then at least could offer some hints.
  
  – Rahul R.
  Mar 21 at 19:13
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Can you show an example of the recursive algorithm? Using iterators it's often possible to convert a recursive algorithm into an iterative one by retaining the state between calls to next().
  
  – Alnitak
  Mar 21 at 19:59
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I figured out an iterative solution to my specific problem: I was trying to generate all subsets of a certain size for a given set. I do this iteratively now by incrementing a set of indices on the original set. I'll leave the question open though, since I think there are definitely algorithms where it's difficult to get an iterative solution.
  
  – rococo
  Mar 21 at 20:31
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  See e.g.jdoodle.com/a/15tZ, where I've generated an O(1) algorithm using iterators to generate each member of the Fibonacci sequence.
  
  – Alnitak
  Mar 21 at 20:32
  
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  stackoverflow.com/questions/931762/…
  
  – Alnitak
  Mar 21 at 20:33
  

  
  
  
  

add a comment | 

I want to create an Iterator in Java (i.e. support hasNext() and next() calls). However, the thing I'm iterating is generated recursively. I want to be able to create this Iterator without having to generate the values beforehand and storing them. Instead, the next() call should get the next value that the recursion outputs, and hasNext() should check that the recursion is not yet done.

Is there a standard pattern for doing this?

Edit: I think a Python yield in a recursive function is the functionality I'm looking for. Not sure how to do it in Java though.

java recursion iterator iteration

share|improve this question

edited Mar 21 at 19:20

rococo

asked Mar 21 at 19:09

rococorococo

4511517

share|improve this question

edited Mar 21 at 19:20

rococo

asked Mar 21 at 19:09

rococorococo

4511517

share|improve this question

edited Mar 21 at 19:20

rococo

asked Mar 21 at 19:09

rococorococo

4511517

asked Mar 21 at 19:09

rococorococo

4511517

asked Mar 21 at 19:09

rococorococo

4511517