Java Stream map custom object to DoubleStream and get max value
import java.util.Arrays; import java.util.List; import java.util.OptionalDouble; public class Main { public static void main(String[] args) { Language[] langArray = { // new Language("CSS", 55555), // new Language("HTML", 66666), // new Language("Java", 44444.5), // new Language("Javascript", 77777.77), // new Language("C++", 88888), // new Language("C", 33333), // new Language("SQL", 99999.4) };// List<Language> langList = Arrays.asList(langArray); langList.stream().forEach(System.out::println); OptionalDouble income = langList .stream()//from w w w. j av a 2 s.c om .mapToDouble(l -> l.getSalary()) .max(); if (income.isPresent()) { System.out.println("Highest income: " + income.getAsDouble()); } else { System.out.println("Could not get the highest income."); } } } class Language { private String firstName; private double salary; public Language(String firstName, double salary) { this.firstName = firstName; this.salary = salary; } public String getFirstName() { return firstName; } public double getSalary() { return salary; } @Override public String toString() { return String.format("%-20s %8.2f", getFirstName(), getSalary()); } }