String as key to look up an Integer

[albert kao]

I like to use String as key to look up an Integer.
Therefore I try the following code, but it has compile error:

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

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

The following code has compile error too:

Map<String, Integer> map;
map.put("hi", new Integer(1));
map.put("hello", new Integer(2));

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]

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]

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:

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

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

[Rob Spoor]

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

[Ernest Friedman-Hill]

Sorry, didn't notice they were missing.

[Rob Spoor]

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