Stream min() method in Java with Examples

Last Updated : 25 Jul, 2019

Stream.min() returns the minimum element of the stream based on the provided Comparator. A Comparator is a comparison function, which imposes a total ordering on some collection of objects. min() is a terminal operation which combines stream elements and returns a summary result. So, min() is a special case of reduction. The method returns Optional instance.

Syntax :

  Optional<T> min(Comparator<? super T> comparator)    Where, Optional is a container object which  may or may not contain a non-null value   and T is the type of objects  that may be compared by this comparator

Exception : This method throws NullPointerException if the minimum element is null.

Example 1 : Minimum from list of Integers.

   // Java code for Stream.min() method to get 
// the minimum element of the Stream 
// according to the provided Comparator. 
import java.util.*; 
  
class GFG { 
  
    // Driver code 
    public static void main(String[] args) 
    { 
  
        // Creating a list of integers 
        List<Integer> list = Arrays.asList(-9, -18, 0, 25, 4); 
  
        // Using stream.min() to get minimum 
        // element according to provided Integer Comparator 
        Integer var = list.stream().min(Integer::compare).get(); 
  
        System.out.print(var); 
    } 
} 
 
  

Output :

-18

Example 2 : Reverse comparator to get maximum value using min() function.

   // Java code for Stream.min() method 
// to get the minimum element of the  
// Stream according to provided comparator. 
import java.util.*; 
  
class GFG { 
  
    // Driver code 
    public static void main(String[] args) 
    { 
  
        // Creating a list of integers 
        List<Integer> list = Arrays.asList(-9, -18, 0, 25, 4); 
  
        // Using Stream.min() with reverse 
        // comparator to get maximum element. 
        Optional<Integer> var = list.stream() 
                    .min(Comparator.reverseOrder()); 
  
        // IF var is empty, then output will be Optional.empty 
        // else value in var is printed. 
        if(var.isPresent()){ 
        System.out.println(var.get()); 
        } 
        else{ 
            System.out.println("NULL"); 
        } 
          
    } 
} 
 
  

Output :

Example 3 : Comparing strings based on last characters.

   // Java code for Stream.min() method 
// to get the minimum element of the  
// Stream according to provided comparator. 
import java.util.*; 
  
class GFG { 
  
    // Driver code 
    public static void main(String[] args) 
    { 
  
        // creating an array of strings 
        String[] array = { "Geeks", "for", "GeeksforGeeks", 
                           "GeeksQuiz" }; 
  
        // The Comparator compares the strings 
        // based on their last characters and returns 
        // the minimum value accordingly. 
        Optional<String> MIN = Arrays.stream(array).min((str1, str2) ->  
                    Character.compare(str1.charAt(str1.length() - 1),  
                                      str2.charAt(str2.length() - 1))); 
  
        // If a value is present, 
        // isPresent() will return true 
        if (MIN.isPresent())  
            System.out.println(MIN.get());  
        else
            System.out.println("-1");  
    } 
} 
 
  

Output :

for

Stream peek() Method in Java with Examples

Sahil_Bansall

Improve

Article Tags :

Practice Tags :

Stream min() method in Java with Examples

Similar Reads