• Post Reply Bookmark Topic Watch Topic
  • New Topic
programming forums Java Mobile Certification Databases Caching Books Engineering Micro Controllers OS Languages Paradigms IDEs Build Tools Frameworks Application Servers Open Source This Site Careers Other Pie Elite all forums
this forum made possible by our volunteer staff, including ...
Marshals:
  • Campbell Ritchie
  • Jeanne Boyarsky
  • Ron McLeod
  • Paul Clapham
  • Liutauras Vilda
Sheriffs:
  • paul wheaton
  • Rob Spoor
  • Devaka Cooray
Saloon Keepers:
  • Stephan van Hulst
  • Tim Holloway
  • Carey Brown
  • Frits Walraven
  • Tim Moores
Bartenders:
  • Mikalai Zaikin

Sorting hashmap

 
Ranch Hand
Posts: 18944
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
I have a hasmap and the data stored is like

map.put("10-abc",vector)
map.put("30-rst",vector)
map.put("20-xyz",vector)
map.put("40-def",vector)

I would like to sort by key. Is this possible if so how?
 
author and iconoclast
Posts: 24207
46
Mac OS X Eclipse IDE Chrome
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
Use a TreeMap instead of a HashMap. It's automatically sorted by key -- that's what it's for.
 
Anonymous
Ranch Hand
Posts: 18944
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
Tree Map has same properties as Hashmap or different. If so, why do we have HashMap?
 
Ernest Friedman-Hill
author and iconoclast
Posts: 24207
46
Mac OS X Eclipse IDE Chrome
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
The price you pay for sorting is lower performance. HashMap has amortized constant-time performance for put and get operations, while TreeMap has ln(N) performance (i.e., the performance is proportional to the logarithm of the size.

All this is actually discussed in some detail on the Javadoc pages for these, and other, java.util classes -- it's worth taking the time to read the introductions at the top of a page when you are using a class you're new to.
 
Here. Have a potato. I grew it in my armpit. And from my other armpit, this tiny ad:
a bit of art, as a gift, the permaculture playing cards
https://gardener-gift.com
reply
    Bookmark Topic Watch Topic
  • New Topic