Really simple question hopefully. I want to do something like this:
Map<String, String> temp = { colName, data };
Where colName, data are string variables.
Thanks.
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1Even though it's not available now, I believe this will land in Java 8 unless they dropped it when I wasn't paying attention.Joel– Joel2012-07-30 01:40:51 +00:00Commented Jul 30, 2012 at 1:40
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3 Answers
Map is an interface. Create an instance of one the classes that implements it:
Map<String, String> temp = new HashMap<String, String>();
temp.put(colName, data);
Or, in Java 7:
Map<String, String> temp = new HashMap<>();
temp.put(colName, data);
2 Comments
Ismael
can you explain why in java7 is that possible?
John Girata
In Java 7, support was added for omitting the types in certain cases. It's just to make the code a little cleaner.
@JohnGirata is correct.
If you're REALLY upset, you could have a look here http://nileshbansal.blogspot.com.au/2009/04/initializing-java-maps-inline.html
It's not quite what you're asking, but is a neat trick/hack non the less.
Comments
The quick way of putting entries in a Map just created is the following (let me use a HashMap 'cause I like them):
Map<String,String> temp = new HashMap<String,String>(){{
put(colName, data);
}};
Note all those parenthesis with a closing semicolon!
While it's true that in Java7 you can generally use the diamond operator and write something like this Map<String,String> temp = new HashMap<String,String>();, this does not work when putting elements in the Map inline. In other words, the compiler with yell at you if you try the following (don't ask me why):
Map<String,String> temp = new HashMap<>(){{
put(colName, data);
}};
answered Jul 30, 2012 at 1:49
Marsellus Wallace
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