SAVE TIME AND ENERGY WITH THE MAP.ENTRY CLASS

Are you tired of having to obtain the keys for a Map and then the value
for each key? With the Map.Entry class, you can retrieve all of this
information at the same time. The standard way to iterate over a Map is 
to
enter the following:

Set keys = map.keySet( );
if(keys != null) {
    Iterator iterator = keys.iterator( );
    while(iterator.hasNext( )) {
        Object key = iterator.next( );
        Object value = map.get(key);
        ....
    }
}

However, this method has one problem. After getting the keys from the
Map, you have to go back to the Map each time to retrieve the value, 
which
is tedious and time-consuming.

Fortunately, there's a simpler way. The Map class provides a method
called 'entrySet' that returns a Set of Map.Entry objects. The 
Map.Entry
class then provides a getKey and a getValue method so the above code 
can be
written more logically. For example:

Set entries = map.entrySet( );
if(entries != null) {
    Iterator iterator = entries.iterator( );
    while(iterator.hasNext( )) {
        Map.Entry entry = iterator.next( );
        Object key = entry.getKey( );
        Object value = entry.getValue( );
        ....
    }
}

While this adds an extra line of code, it saves on the unnecessary 
'get'
call back to the Map and provides the developer with a useful class 
that
holds both the key and the value. Map.Entry also provides a setValue
method that allows the developer to change the value in the map.

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