Iterate over a java map and change values

Question

I have a map of <CheckBox, ImageButton>.

I want to be able to iterate over this map and change the image of each ImageButton. Is there any way I can do this? getValue() doesn't seem to let me use the methods associated with each ImageButton.

Isn't this just iterating using `getValue()`? I'm unable to call `setImageBitmap()` on `getValue()`. It seems like I'd have to create another ImageButton object and set that equal to `getValue()`. But then if I change that new ImageButton, wont my original one stay the same? — Brejuro, Aug 16 '15 at 21:33

score 1 · Answer 1 · answered Aug 16 '15 at 22:32

// support you define your hash map like this
HashMap<CheckBox,ImageButton> hs = new HashMap<CheckBox,ImageButton>();
// then
for(Map.Entry<CheckBox, ImageButton> e : hs.entrySet())
{
    ImageButton imgBtn = e.getValue();
    // do whatever you like to imgBtn
}

score 0 · Answer 2 · answered Aug 16 '15 at 21:31

0

A HashMap? Use HashMap.values() to get a Collection of the saved Values. http://docs.oracle.com/javase/7/docs/api/java/util/HashMap.html#values()

answered Aug 16 '15 at 21:31

Luka Jacobowitz

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score 0 · Answer 3 · answered Aug 16 '15 at 21:33

0

You can iterate over the keys of a Map using keySet, and get the value associated with each individual key:

for (CheckBox cb : checkBoxes.keySet()) {
    ImageButton btn = checkBoxes.get(cb);
}

answered Aug 16 '15 at 21:33

Sebastian

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score 0 · Accepted Answer · edited May 23 '17 at 11:51

0

Taken from this answer

You have to cast the result of getValue to an ImageButton to use its functions.

Iterator it = mp.entrySet().iterator();
while (it.hasNext()) {
    Map.Entry pair = (Map.Entry)it.next();
    ((ImageButton)pair.getValue()).setImageBitmap(bitmap);
}

edited May 23 '17 at 11:51

Community

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answered Aug 16 '15 at 21:33

aProperFox

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You should be using generics, as the warning you're getting specifically indicates, exactly to avoid this. – chrylis -cautiouslyoptimistic- Aug 16 '15 at 22:45

Iterate over a java map and change values

4 Answers4