CODEWITHSUNDEEP
arraylistjava-8java-stream
Karthikeyan
Karthikeyan

Reputation: 161

how to find the max value of nested arraylist of string using streams

I have an ArrayList in the below format

List<List<String>> ll = [["0", "a"], ["1", "b"], ["0", "c"], ["1", "d"]]

I want to find the maximum value by considering the first position in the nested list. How can I do it using streams?

Using streams how to find the maximum value by taking the position at Integer.parseInt(ll.get(i).get(0))

Upvotes: 2

Views: 994

Answers (2)

Ravindra Ranwala
Ravindra Ranwala

Reputation: 21124

You may do it like so,

int max = ll.stream().mapToInt(l -> Integer.parseInt(l.get(0))).max()
        .orElseThrow(IllegalArgumentException::new);

Upvotes: 1

Nicholas K
Nicholas K

Reputation: 15423

Firstly, the code you posted doesn't even compile. One approach of fetching the largest number from a nested list.

List<List<String>> ll = Arrays.asList(Arrays.asList("10", "a"), Arrays.asList("21", "b"), Arrays.asList("10", "c"),
                Arrays.asList("11", "d"));

OptionalInt max = ll.stream().flatMap(l -> l.stream()).filter(str -> Character.isDigit(str.charAt(0)))
                .distinct().mapToInt(i -> Integer.parseInt(i)).max();

System.out.println(max.getAsInt());

Upvotes: 1

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