Java - Displaying key in map with most occurrences

I have a string and i created a map which schows occurrences of characters:

String: "aaa bbbb ccccccccccc ddddd eeee"
map: {a=3, b=4, c=11, d=5, e=4}

And i want to display only c, also output:

(because it occurres most of the times).

CodePudding user response：

You can find the max key using streams like this:

Character maxKey = map.entrySet().stream()
    .max(Map.Entry.comparingByValue())
    .get().getKey();

CodePudding user response：

There are many ways. Here is how I would do it.

Assuming your keys are strings.

stream the entry set.
get the max using the Entry comparator for value.
get the Entry of the optional and then get the string.

Map<String, Integer> maps = Map.of("c", 11, "d", 17, "f", 12);
String key = maps.entrySet().stream()
        .max(Entry.comparingByValue())
        .get().getKey();
System.out.println(key);

prints

You can also combine the two operations and use the chars().stream() method.

stream the characters
map to a Character object.
and count the characters grouping by the character
stream the entry set as before
and return the character.

String str = "aaa bbbb ccccccccccc ddddd eeee";
char key = str.chars()
        .mapToObj(ch -> Character.valueOf((char) ch))
        .collect(Collectors.groupingBy(s -> s,
                Collectors.counting()))
        .entrySet().stream().max(Entry.comparingByValue())
        .get().getKey();

System.out.println(key);

In this case, prints

If you only want letters to be counted you can filter with Character.isLetter()