Converting from Hashmap to Array

Question

I've been searching around for this but I can't seem to find a solution that works. I currently have a hashmap

 HashMap<String,Float> map = new HashMap<String,Float>();

Now I want to access just the key part of the hashmap which is a column of strings. And I would like to create a new array of Strings from those values. If I were to just convert them:

map.getKey().toArray();

That would give the float values too in it's array.. So how do I do this?

Oliver Charlesworth · Accepted Answer · 2012-06-02 11:11:29Z

7

map.keySet().toArray(new String[0]);

See http://docs.oracle.com/javase/6/docs/api/java/util/HashMap.html#keySet%28%29.

answered Jun 2, 2012 at 11:11

Oliver Charlesworth

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Daniel Kamil Kozar Over a year ago

Now that's an answer I can +1. ;)

Ingo Kegel · Accepted Answer · 2012-06-02 11:16:10Z

2

map.keySet().toArray(new String[map.size()]);

will give you a string array with the keys in the map. Casting map.keySet().toArray() to String[] will not work because it returns an array of type Object.

answered Jun 2, 2012 at 11:16

Ingo Kegel

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Comments

Daniel Kamil Kozar · Accepted Answer · 2012-06-02 11:11:46Z

0

I don't know what a "column of strings" is, but what you're looking for is this :

String[] key_array = (String[])map.keySet().toArray();

answered Jun 2, 2012 at 11:11

Daniel Kamil Kozar

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