My input is a n number of strings . I want to get the unique values , as well as number of occurance of these string case insensitive.
I have a thought of getting the input in array ; sort it and do loops to calculate the occurance. Is there any other way?
You can use the Stream api facilities to get what you want:
List<String> list = Arrays.asList("hello","world","Hola","Mundo","hello", "world","Hola","Mundo","mundo","Hello","Hola","mundo","Mundo");
Map<String, Long> ocurrences = list
.stream()
.map(String::toLowerCase) // make case insensitive
.collect(Collectors.groupingBy(Function.identity(), Collectors.counting()));
System.out.println(ocurrences);
Output:
{world=2, mundo=5, hello=3, hola=3}
public Map<String, Integer> calculateOccurences(Collection<String> collectionOfStrings) {
HashMap<String, Integer> map = new HashMap<String, Integer>();
for (String string : collectionOfStrings) {
String stringAsLowerCase = string.toLowerCase();
Integer integer = map.get(stringAsLowerCase);
if (integer == null) { //this has never been added
map.put(stringAsLowerCase, 1);
} else {
map.put(stringAsLowerCase, integer + 1);
}
}
return map;
}
This will return a map where the keys are the unique words and each value will tell you how many times it appeared.
Integer integer = map.getOrDefault(stringAsLowerCase, 0); then you can get rid of the conditional logic