Java8: Lambdas & Internal Iterators

Java8 introduced a new type of iterator called internal iterators.

External iterators are

for(int i=0;i<list.size();i++){

and

for(Person p:list)

Below is an example for a Internal iterator introduced in Java 8. Let’s see how can we iterate a Person object list.

class Person{
    String name;
    int age;
    Person(String name, int age){
        this.age=age;
        this.name=name;
    }
    @Override
    public String toString(){
        return name +"'s age is " + age;
    }
}

We will create a list of objects and iterate.

List<Person> list= Arrays.asList(
                new Person("nuwan",20),
                new Person("sen",30)
        );        
list.forEach(System.out::println);

With a single line of code we can print whole list.

list.forEach(System.out::println);

This line accepts get the objects in the list and print. In-order to have a readable out put we may have to override the toString method of the Person class as these lambdas work with single arguments only.

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As in this forEach implementation we aren’t controlling the execution unlike external iterators it can help parallel processioning heavily.

Ref: https://youtu.be/tfbmYBcq5CM

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