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How can we iterate the elements of List and Map using lambda expression in Java?
The lambda expressions are inline code that implements a functional interface without creating an anonymous class. In Java 8, forEach statement can be used along with lambda expression that reduces the looping through a Map to a single statement and also iterates over the elements of a list. The forEach() method defined in an Iterable interface and accepts lambda expression as a parameter.
Example ( List using Lambda Expression)
import java.util.*;
public class ListIterateLambdaTest {
public static void main(String[] argv) {
List<String> countryNames = new ArrayList<String>();
countryNames.add("India");
countryNames.add("England");
countryNames.add("Australia");
countryNames.add("Newzealand");
countryNames.add("South Africa");
// Iterating country names through forEach using Lambda Expression
countryNames.forEach(name -> System.out.println(name));
}
}Output
India England Australia Newzealand South Africa
Example (Map using Lambda Expression)
import java.util.*;
public class MapIterateLambdaTest {
public static void main(String[] args) {
Map<String, Integer> ranks = new HashMap<String, Integer>();
ranks.put("India", 1);
ranks.put("Australia", 2);
ranks.put("England", 3);
ranks.put("Newzealand", 4);
ranks.put("South Africa", 5);
// Iterating through
forEach using Lambda Expression
ranks.forEach((k,v) -> System.out.println("Team : " + k + ", Rank : " + v));
}
}Output
Team : Newzealand, Rank : 4 Team : England, Rank : 3 Team : South Africa, Rank : 5 Team : Australia, Rank : 2 Team : India, Rank : 1
Updated on: 11-Jul-2020
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