Java Collections max()

🎓 Check Out My Top 25 Udemy Courses (80-90% Discount): My Udemy Courses - Ramesh Fadatare

In this guide, you will learn about the Collections max() method in Java programming and how to use it with an example.

1. Collections max() Method Overview

Definition:

The max() method of the Collections class in Java is used to return the maximum element of the given collection, according to the natural ordering of its elements.

Syntax:

Collections.max(Collection<? extends T> coll)

Parameters:

coll: The collection whose maximum element is to be determined.

Key Points:

- The collection must not be empty, or else a NoSuchElementException will be thrown.

- All elements in the collection must be mutually comparable using the provided comparator (or the natural ordering if using the method without a comparator), otherwise, a ClassCastException is thrown.

- There is an overloaded version of max() that takes a custom comparator as an argument to determine the maximum element based on the comparator's ordering.

2. Collections max() Method Example

import java.util.*;

public class CollectionsMaxExample {
    public static void main(String[] args) {
        List<Integer> numbers = new ArrayList<>(Arrays.asList(15, 23, 7, 31, 12));

        // Finding the maximum number in the list
        int maxNumber = Collections.max(numbers);
        System.out.println("Maximum number in the list: " + maxNumber);

        // Finding the maximum string based on length using a custom comparator
        List<String> words = new ArrayList<>(Arrays.asList("apple", "banana", "kiwi"));
        String longestWord = Collections.max(words, Comparator.comparingInt(String::length));
        System.out.println("Longest word in the list: " + longestWord);
    }
}

Output:

Maximum number in the list: 31
Longest word in the list: banana

Explanation:

In the provided example, we first create a list of integers and determine the maximum number using the max() method. Next, we create a list of strings and determine the longest word by providing a custom comparator to the max() method that compares strings based on their lengths.