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String as key to look up an Integer

albert kao
Ranch Hand

Joined: Feb 04, 2010
Posts: 249
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.
Ernest Friedman-Hill
author and iconoclast
Marshal

Joined: Jul 08, 2003
Posts: 24187
    
  34

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>;




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albert kao
Ranch Hand

Joined: Feb 04, 2010
Posts: 249
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)
Rob Spoor
Sheriff

Joined: Oct 27, 2005
Posts: 19781
    
  20

Try adding () after the last >. After all, each method and constructor call needs them.


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Ernest Friedman-Hill
author and iconoclast
Marshal

Joined: Jul 08, 2003
Posts: 24187
    
  34

Sorry, didn't notice they were missing.
Rob Spoor
Sheriff

Joined: Oct 27, 2005
Posts: 19781
    
  20

Generics, with their added < and >, do make it a bit harder to see missing ().
 
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