Java hashmap returns null

Question

I'm receiving a null value from my hashmap. This is the hashmap creation:

private HashMap<String,Bitmap> thumbs = new HashMap<String,Bitmap>();

/* adding a single value to the hashmap */

Then I proceed to retreiving the value from the hashmap, like so:

    public Bitmap getImageByFileName(String fileName) {

    Bitmap fish = null;
    Iterator it = thumbs.entrySet().iterator();
    while (it.hasNext()) {
        Map.Entry pairs = (Map.Entry)it.next();
        fish = (Bitmap)thumbs.get(fileName);        
        it.remove(); 
    }   
    Log.i("shnitzel", " bitmap is " + fish);
    fish = (Bitmap)thumbs.get(fileName);
    Log.i("shnitzel", " final bitmap is " + fish);
    return fish;
}

The log file:

08-05 22:18:28.170: I/shnitzel(477):  bitmap is android.graphics.Bitmap@40650138
08-05 22:18:28.170: I/shnitzel(477):  final bitmap is null

As you can see, I use the exact same command inside and outside the 'while' loop, but for some reason it works inside it, but not outside. Why does this happen?

:( Embarrassing indeed. I actually only added this while loop to see why I was receiving a null value to begin with. I honestly have no idea why it didn't work before, but does now. Thanks anyway :) — n00b programmer
– n00b programmer, Commented Aug 5, 2013 at 19:36
Glad to hear the problem's solved! Please select an answer to close your question. — William Morrison
– William Morrison, Commented Aug 5, 2013 at 21:52

DUman · Accepted Answer · 2013-08-05 19:29:44Z

3

In your loop:

it.remove();

You're removing the element after having read it.

answered Aug 5, 2013 at 19:29

DUman

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Comments

William Morrison · Accepted Answer · 2013-08-05 19:29:29Z

1

it.remove() is removing the entry from the HashMap.

According to the documentation:

The set is backed by the map, so changes to the map are reflected in the set, and vice-versa.

answered Aug 5, 2013 at 19:29

William Morrison

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