Ways to Iterate Over a Collection in Java

In this short Java tutorial I am going to share with you a few different ways you can use to iterate over a collection in Java.

Iterating List with Enhanced For-Loop

 List<String> names = new ArrayList<>();
 names.add("Sergey");
 names.add("Bill");
 names.add("John");

for(String name: names)
{
    System.out.println(name);
}

Iterating List with forEach() and Lambda

List<String> names = new ArrayList<>();
names.add("Sergey");
names.add("Bill");
names.add("John");

names.forEach(name -> System.out.println(name));

forEach, Stream, Filter and Lamda

List<String> names = new ArrayList<>();
names.add("Sergey");
names.add("Bill");
names.add("John");

names.stream().filter(s->s.contains("S")).forEach(name -> System.out.println(name));
       

Iterating List Using Iterator

 List<String> names = new ArrayList<>();
 names.add("Sergey");
 names.add("Bill");
 names.add("John");
 
 Iterator iter = names.iterator();
 while(iter.hasNext())
 {
    System.out.println(iter.next());
 }

Iterating Over Map with Enhanced For-Loop

Map<String, String> keyValues = new HashMap<>();
keyValues.put("firstName", "Sergey");
keyValues.put("lastName", "Kargopolov");
keyValues.put("country", "Canada");

for (Map.Entry<String, String> entry : keyValues.entrySet()) {
 System.out.println(entry.getKey() + " : " + entry.getValue());
}

Iterating Over Map with forEach() and Lambda

Map<String, String> keyValues = new HashMap<>();
keyValues.put("firstName", "Sergey");
keyValues.put("lastName", "Kargopolov");
keyValues.put("country", "Canada");

keyValues.forEach((key,value)->System.out.println(key + " : " + value));

Iterating Over Map Using EntrySet

Map<String, String> keyValues = new HashMap<>();
keyValues.put("firstName", "Sergey");
keyValues.put("lastName", "Kargopolov");
keyValues.put("country", "Canada");
       
keyValues.entrySet().forEach(entry -> System.out.println(entry.getKey() + " : " + entry.getValue()));
  

I hope this short Java tutorial with code examples on how to iterate over a List and Map in Java was helpful for you.

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