How to achieve this Map<String, List<>> structure

Question

I have data like below:

 Key       value
-----      ------
car         toyota
car         bmw
car         honda

fruit       apple
fruit       banana

computer    acer
computer    asus
computer    ibm 
...

(Each row of above data is an object with fields "key" and "value", all in one List List<DataObject>)

I would like to construct the data to a Map<String, List<String>> like following:

 "car"      : ["toyota", "bmw", "honda"]
 "fruit"    : ["apple","banana"]
 "computer" : ["acer","asus","ibm"]

How to achieve above Map structure from the data objects?

******Besides******

I am more interested in using pure JDK provided classes or interfaces to achieve the result instead of using external library. Any help?

Answer 1

    Map<String, List<String>> myMaps = new HashMap<String, List<String>>();
    for (DataObject item : myList) {
        if (!myMaps.containsKey(item.getKey())) {
            myMaps.put(item.getKey(), new ArrayList<String>());
        }
        myMaps.get(item.getKey()).add(item.getValue());
    }