Imagine we want to produce a Map with each unique word as a key and it’s frequency as the value.
Prior to Java 8 we would have to do something like this:
Map<String, Integer> map = new HashMap<>();
for(String word : words) {
if(map.containsKey(word)) {
int count = map.get(word);
map.put(word, ++count);
} else {
map.put(word, 1);
}
}
However with the map.merge method we can now do:
Map<String, Integer> map = new HashMap<>();;
for(String word : words) {
map.merge(word, 1, Integer::sum);
}
return map;
Pretty nice eh?
