Failure to Loop Through Map in JSP

Question

Possible Duplicate:
How do I iterate over each Entry in a Map?

I'm following this solution to no effect: https://stackoverflow.com/a/1835742/666468

I am trying to output this Map:

//protected Map<String,String> getImageTagAttributes()
Image image = new Image(resource);
for (Map<String, String> foo : image.getImageTagAttributes()) {
        String key = foo.getKey();
        String value = foo.getValue();

        //output here
    }

But I get this error: Can only iterate over an array or an instance of java.lang.Iterable

I imported java.util.Iterator as well, but no luck.

p.s. I wish I could install and use JSTL, but it's not my call.

What is returned by `image.getImageTagAttributes()`? A `Map` has a key/value pair mechanism. You need to use an `EntrySet` to iterate over the `Map`. — Lion, Jan 31 '13 at 17:36
Use the iterator as suggested in the following solution : http://stackoverflow.com/questions/672916/how-to-get-image-height-and-width-using-java — Zafer, Jan 31 '13 at 17:37
How did you miss the `entrySet()` method in the answer you found? — BalusC, Jan 31 '13 at 17:45
@BalusC, I presumed `countries.entrySet()` is unique to the example in question, and not to me specifically. My knowledge in Java is rookie at best. — justacoder, Jan 31 '13 at 18:32

score 2 · Accepted Answer · answered Jan 31 '13 at 17:43

Not sure where did you get that Image class, but if image.getImageTagAttributes() returns Map<String, String> then maybe try it this way

Image image = new Image(resource);
Map<String, String> map = image.getImageTagAttributes();
for (Map.Entry<String,String> foo : map.entrySet()) {
    String key = foo.getKey();
    String value = foo.getValue();

    //output here
}

score 0 · Answer 2 · answered Jan 31 '13 at 17:36

0

You cannot iterate a Map in for each loop.

Get the map object keyset and then iterate it.

Then inside the for loop try retrieving the value for each key from the map.

answered Jan 31 '13 at 17:36

user1760178

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Dimitri · Answer 3 · 2013-01-31T17:42:19.550

Because this not the correct way to iterate over a Map :

    Image image = new Image(resource);
    Map<String, String> foo =  image.getImageTagAttributes();
    Set<String> key = foo.keyset(); 
     for ( k : keys ) {
           String value = foo.get(k);
        //output here
    }

or you can interate that way :

    Image image = new Image(resource);
    Map<String, String> foo =  image.getImageTagAttributes();
    Set<Map.Entry<String,String>> entries = foo.entrySet();

    for(Map.Entry<String, String> e : entries){
       String key  = e.getKey();
       String value = e.getValue();
        //output
    }

In my answer, I suppose that image.getImageTagAttributes(); returns a Map<String,String>

Failure to Loop Through Map in JSP

3 Answers3