for loop : Cannot be resolved to a variable

Question

I was wondering why I had this error when I tried to do this :

Map<Integer, List<String>> map = (Map<Integer, List<String>>) parameters;

for(Integer i : map.keySet()) {
    tableFiles.setWidget(row, 0, addPanelFile(String.valueOf(i)));
    row++;
    for(map.get(i)) {

    }
}

Why can't i be resolved to a variable ?

The easiest and most efficient way to iterate through a map if you need both the key and value is to iterate through the Set<Map.Entry<K, V>> returned by entrySet(). Then you don't need to do a get, you already have the value in the Entry. — Mark Peters
– Mark Peters, Commented Jun 13, 2011 at 12:49

aioobe · Accepted Answer · 2011-06-13 12:46:05Z

10

The for-loop is malformed.

Change

for(((Map<Integer, List<String>>) parameters).get(i)) {

}

into

for(SomeType someVar : ((Map<Integer, List<String>>) parameters).get(i)) {

}

and you should get a better error-message.

answered Jun 13, 2011 at 12:46

aioobe

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2 Comments

l0r3nz4cc10 Over a year ago

@Mark Peters : well, that's a typo. Edited

l0r3nz4cc10 Over a year ago

Thanks, I think I'm a bit tired, should have seen this

Buhake Sindi · Accepted Answer · 2011-06-13 13:29:24Z

0

Something of this effect. foreach uses Iterator for iterations;

Map<Integer, List<String>> map = (Map<Integer, List<String>>) parameters;

for (Integer i : map.keySet()) {
    tableFiles.setWidget(row, 0, addPanelFile(String.valueOf(i)));
        row++;
    for (String s: map.get(i)) {

    }
}

edited Jun 13, 2011 at 13:29

answered Jun 13, 2011 at 12:50

Buhake Sindi

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4 Comments

Mark Peters Over a year ago

You don't need to expose the iterator, keySet().iterator() does not return an Iterator<Iterator>, an Iterator is not an Iterable, and you want map not parameters in the inner loop.

l0r3nz4cc10 Over a year ago

Thanks, I think I'm a bit tired, should have seen this

Buhake Sindi Over a year ago

@Mark Peters, thanks, but Map.get() returns a List<String>. Check the OP's edited question.

Mark Peters Over a year ago

Elite: I know what that returns. I was talking about your use of keyIter, which is just wrong since keyIter is not an Iterable. Just use for (Integer i : map.keySet()) , which actually works and doesn't unnecessarily expose the Iterator. On the inner loop, it will fail because presumably parameters isn't declared as a Map<Integer, List<String>> or else the cast to map wouldn't be needed.

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