LongStream filter() in Java with examples

LongStream filter(LongPredicate predicate) returns a stream consisting of the elements of this stream that match the given predicate. This is an intermediate operation. These operations are always lazy i.e, executing an intermediate operation such as filter() does not actually perform any filtering, but instead creates a new stream that, when traversed, contains the elements of the initial stream that match the given predicate.

Syntax :

LongStream filter(LongPredicate predicate)

Where, LongStream is a sequence of primitive long-valued elements.
LongPredicate represents a predicate (boolean-valued function) 
of one long-valued argument and the function returns the new stream.

Example 1 : filter() method on LongStream.

// Java code for LongStream filter
// (LongPredicate predicate) to get a stream
// consisting of the elements of this
// stream that match the given predicate.
import java.util.*;
import java.util.stream.LongStream;

class GFG {

    // Driver code
    public static void main(String[] args)
    {
        // Creating an LongStream
        LongStream stream = LongStream.of(3L, 5L, 6L, 8L, 9L);

        // Using LongStream filter(LongPredicate predicate)
        // to get a stream consisting of the
        // elements that gives remainder 2 when
        // divided by 3
        stream.filter(num -> num % 3 == 2)
            .forEach(System.out::println);
    }
}

Output :

5
8

Example 2 : filter() method on LongStream.

// Java code for LongStream filter
// (LongPredicate predicate) to get a stream
// consisting of the elements of this
// stream that match the given predicate.
import java.util.*;
import java.util.stream.LongStream;

class GFG {

    // Driver code
    public static void main(String[] args)
    {
        // Creating an LongStream
        LongStream stream = LongStream.of(-2L, -1L, 0L, 1L, 2L);

        // Using LongStream filter(LongPredicate predicate)
        // to get a stream consisting of the
        // elements that are greater than 0
        stream.filter(num -> num > 0)
            .forEach(System.out::println);
    }
}

Output :

1
2