• 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

String as key to look up an Integer

 
Ranch Hand
Posts: 260
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
I like to use String as key to look up an Integer.
Therefore I try the following code, but it has compile error:

Syntax error on token(s), misplaced construct(s)

The following code has compile error too:

The local variable map may not have been initialized Map.java line 10 Java Problem
The local variable map may not have been initialized Map.java line 11 Java Problem

Please help.
Thanks.
 
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
Hi Albert,

"Map" isn't a class, it's an interface. You need to create an instance of a class that implements Map, for example HashMap:

Map<String, Integer> map = new HashMap<String, Integer>;



 
albert kao
Ranch Hand
Posts: 260
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator

Ernest Friedman-Hill wrote:Hi Albert,

"Map" isn't a class, it's an interface. You need to create an instance of a class that implements Map, for example HashMap:

Map<String, Integer> map = new HashMap<String, Integer>;





This still has errors:

Syntax error on token(s), misplaced construct(s)
 
Sheriff
Posts: 22781
131
Eclipse IDE Spring VI Editor Chrome Java Windows
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
Try adding () after the last >. After all, each method and constructor call needs them.
 
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
Sorry, didn't notice they were missing.
 
Rob Spoor
Sheriff
Posts: 22781
131
Eclipse IDE Spring VI Editor Chrome Java Windows
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
Generics, with their added < and >, do make it a bit harder to see missing ().
 
Thank you my well lotioned goddess! Here, have my favorite tiny ad!
a bit of art, as a gift, the permaculture playing cards
https://gardener-gift.com
reply
    Bookmark Topic Watch Topic
  • New Topic