HashMap上的数组迭代

Question

is there a simple method to iterate all Arrays which are in one Hashmap?

For example:

 HashMap<String, ArrayList<String>>

i search a element from a array which is in one of the HashValue.

Answer 1

Map<String, List<String>> map = new HashMap<String, List<String>>();

for (List<String> values : map.values()) {
    for (String value : values) {
        // do what you want with the value here.
    }
}

To make this loop shorter take a look on LambdaJ. Jakarta collections also has a lot of classes that may simplify this code. For example class that wraps several collections and exposes API of single collection. Something like CollectionsCollection . But unfortunately this library does not support generics yet.

Answer 2

You should use an iterator to run through hashmaps.

Iterator it = map.entrySet().iterator();
while (it.hasNext()) {
    // code goes here
}