Stream count() method in Java with examples
long count() returns the count of elements in the stream. This is a special case of a reduction (A reduction operation takes a sequence of input elements and combines them into a single summary result by repeated application of a combining operation). This is a terminal operation i.e, it may traverse the stream to produce a result or a side-effect. After the terminal operation is performed, the stream pipeline is considered consumed, and can no longer be used.
Syntax :
long count()
Note : The return value of count operation is the count of elements in the stream.
Example 1 : Counting number of elements in array.
import java.util.*;
class GFG {
public static void main(String[] args)
{
List<Integer> list = Arrays.asList( 0 , 2 , 4 , 6 ,
8 , 10 , 12 );
long total = list.stream().count();
System.out.println(total);
}
}
|
Output :
7
Example 2 : Count number of distinct elements in a list.
import java.util.*;
class GFG {
public static void main(String[] args)
{
List<String> list = Arrays.asList( "GFG" , "Geeks" , "for" , "Geeks" ,
"GeeksforGeeks" , "GFG" );
long total = list.stream().distinct().count();
System.out.println(total);
}
}
|
Output :
4
Last Updated :
06 Dec, 2018
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