Slicing Operations in Stream

In this lesson, we will look at some of the most common slicing methods present in the Streams API.

We'll cover the following

The slicing operations are intermediate operations, and, as the name implies, they are used to slice a stream.

Now, we will look at some of the most common slicing methods present in Streams API.

1. distinct()

The first operation that we are going to discuss is distinct(). It returns a stream consisting of the distinct elements (according to Object.equals(Object)) of this stream.

So, if you have a stream of custom objects then your custom class should override equals() and hashcode() methods.

Let’s look at an example to understand distinct() better. In the below example, we have a list of countries. The list can contain duplicate elements as well. We need to print all the distinct countries.

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import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.stream.Stream;
public class StreamDemo {
    public static void main(String[] args) {
        List<String> countries = new ArrayList<>();
        countries.add("India");
        countries.add("USA");
        countries.add("China");
        countries.add("India");
        countries.add("UK");
        countries.add("China");
        countries.stream()
                .distinct()
                .forEach(System.out::println);
    }
}

2. limit()

This is also an intermediate function. It returns a stream consisting of the elements of this stream, truncated to be no longer than maxSize in length.

Below is the method syntax:

Stream<T> limit(long maxSize)

In our example above, we used the distinct() method to get only the distinct countries. Now we will limit the number of countries to three.

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import java.util.ArrayList;

import java.util.Arrays;

import java.util.List;

import java.util.stream.Stream;



public class StreamDemo {



    public static void main(String[] args) {

        List<String> countries = new ArrayList<>();

        countries.add("India");

        countries.add("USA");

        countries.add("China");

        countries.add("India");

        countries.add("UK");

        countries.add("China");



        countries.stream()

                .distinct()

                .limit(3)

                .forEach(System.out::println);

    }

}

3) skip()

Like distinct() and limit(), skip() is also an intermediate method. It returns a stream consisting of the remaining elements of this stream after discarding the first n elements of the stream.

Below is the syntax of this method.

Stream<T> skip(long n)

If this stream contains fewer than n elements then an empty stream will be returned.

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import java.util.ArrayList;

import java.util.Arrays;

import java.util.List;

import java.util.stream.Stream;



public class StreamDemo {



    public static void main(String[] args) {

        List<String> countries = new ArrayList<>();

        countries.add("India");

        countries.add("USA");

        countries.add("China");

        countries.add("India");

        countries.add("UK");

        countries.add("China");



        countries.stream()

                .distinct()

                .skip(2)

                .forEach(System.out::println);

    }

}

This is all we have for slicing functions. In the next lesson, we will look at matching functions.

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