JAVA EXAMPLE PROGRAMS

JAVA EXAMPLE PROGRAMS

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Java 8 - forEach method example with Map


forEach is a new method introduced in Java 8 to iterate over collections. Here is an example on forEach method to iterate over Map.

package com.java2novice.java8;

import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;

public class ForEachMapEx {

	public static void main(String a[]) {

		Map<String, String> countryMap = new HashMap<>();
		countryMap.put("India", "Delhi");
		countryMap.put("USA", "Washington, D.C.");
		countryMap.put("Japan", "Tokyo");
		countryMap.put("Canada", "Ottawa");

		// iterate through Map normal way
		ForEachMapEx.iterateMap(countryMap);

		// iterate through Map using forEach method
		ForEachMapEx.iterateMapUsingForEach(countryMap);
	}

	public static void iterateMap(Map<String, String> countryMap) {

		System.out.println("<----------Iterating in normal way------------->");
		for(Entry<String, String> entry:countryMap.entrySet()) {
			System.out.println("Country: "+entry.getKey()+" : Capital: "+entry.getValue());
		}
	}

	public static void iterateMapUsingForEach(Map<String, String> countryMap) {

		System.out.println("\n<----------Iterating using forEach method------------>");
		countryMap.forEach((k,v)->System.out.println("Country: "+k+" : Capital: "+v));

		countryMap.forEach((k,v)->{
			// you can implement some business logic here..



		});
	}
}

Output:
<----------Iterating in normal way------------->
Country: Canada : Capital: Ottawa
Country: USA : Capital: Washington, D.C.
Country: Japan : Capital: Tokyo
Country: India : Capital: Delhi

<----------Iterating using forEach method------------>
Country: Canada : Capital: Ottawa
Country: USA : Capital: Washington, D.C.
Country: Japan : Capital: Tokyo
Country: India : Capital: Delhi
 Next Program >>

Java 8 forEach method examples

  1. Java 8 forEach example with Map
  2. Java 8 forEach example with List
Knowledge Centre
Inner class and Anonymous class
Inner class: classes defined in other classes, including those defined in methods are called inner classes. An inner class can have any accessibility including private.

Anonymous class: Anonymous class is a class defined inside a method without a name and is instantiated and declared in the same place and cannot have explicit constructors.
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About Author

I'm Nataraja Gootooru, programmer by profession and passionate about technologies. All examples given here are as simple as possible to help beginners. The source code is compiled and tested in my dev environment.

If you come across any mistakes or bugs, please email me to [email protected].

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Reference: Java™ Platform Standard Ed. 7 - API Specification | Java™ Platform Standard Ed. 8 - API Specification | Java is registered trademark of Oracle.
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