Fill hash map during creation

Question

Possible Duplicate:
How to Initialise a static Map in Java

How to fill HashMap in Java at initialization time, is possible something like this ?

public static Map<byte,int> sizeNeeded=new HashMap<byte,int>(){1,1};

score 60 · Accepted Answer · edited Oct 08 '21 at 15:24

60

byte, int are primitive, collection works on object. You need something like this:

public static Map<Byte, Integer> sizeNeeded = new HashMap<Byte, Integer>() {{
    put(new Byte("1"), 1);
    put(new Byte("2"), 2);
}};

This will create a new map and using initializer block it will call put method to fill data.

edited Oct 08 '21 at 15:24

Mike

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answered Jan 27 '11 at 09:59

jmj

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2

Not me, but probably because of `new Byte((byte) 1)`.. and maybe not relying on autoboxing.. And the not used `;` at the end of the init clause.. just looks ugly! – dacwe Jan 27 '11 at 10:07
@dacwe thanks for pointing out that cast thing. – jmj Jan 27 '11 at 10:20
3

-1 from be because I think this is a horrible abuse, and you're not even explaining what it is. – Michael Borgwardt Jan 27 '11 at 10:42
@Mich agree. added info. Thanks. – jmj Jan 27 '11 at 10:46

score 2 · Answer 2 · answered Jan 27 '11 at 10:01

First of all, you can't have primitives as generic type parameters in Java, so Map<byte,int> is impossible, it'll have to be Map<Byte,Integer>.

Second, no, there are no collection literals in Java right now, though they're being considered as a new feature in Project Coin. Unfortunately, they were dropped from Java 7 and you'll have to wait until Java 8...

Fill hash map during creation

2 Answers2