Java Stream limit()
May 17, 2020
limit method of Stream returns a new stream consisting the elements of this stream truncated to given max size in length. The limit method consists the first n elements where n is less or equal to given max size.
Find the
limit method declaration from Java doc.
Stream<T> limit(long maxSize)
limit.
The
limit method returns new Stream.
The method throws
IllegalArgumentException if the parameter maxSize is -ve.
The
limit method is a short-circuiting stateful intermediate operation.
Stream operations are divided into intermediate and terminal operations and are combined to form stream pipelines. An intermediate operation is a short-circuiting if it may produce a finite stream for infinite input. Intermediate operations are divided into stateless and stateful operations. Stateless operations retain no state from previously seen element when processing a new element such as
filter and map. Stateful operations may incorporate state from previously seen elements when processing new elements such as distinct and limit.
Note: The
limit method is a cheap operation on sequential stream pipelines and can be expensive for ordered parallel pipelines, especially for large value of maxSize. This is because limit(maxSize) is bound to return first maxSize elements in encounter order and not any element of maxSize number.
Now we will discuss the
limit method examples.
Example-1:
Suppose we have a stream of numbers and we are calling
limit method on it.
Stream.of(11, 12, 13, 14, 15).limit(3) .forEach(s->System.out.println(s));
limit(3) with max size 3. Hence our output will be up to 3 elements starting from first element i.e. 11 12 13.
If max size of
limit is greater than the number of elements, then all the elements of stream will be selected by limit method. Find the code below.
Stream.of("A", "B", "C", "D").limit(10)
.forEach(s->System.out.println(s));
limit with max size 10. Here limit will return stream with all elements and the output will be A B C D.
Example-2:
Find the more examples of
limit method.
LimitDemo2.java
package com.concretepage;
import java.util.Arrays;
import java.util.List;
public class LimitDemo2 {
public static void main(String[] args) {
System.out.println("--- code 1 ---");
List<String> list = Arrays.asList("Vijay", "Suresh", "Vinod");
list.stream()
.map(e -> "Mr. " + e)
.limit(2)
.forEach(s->System.out.printf("%s ", s));
System.out.println("\n--- code 2 ---");
List<Integer> numList = Arrays.asList(31, 32, 33, 34);
numList.stream()
.mapToInt(i -> i * 10)
.limit(3)
.forEach(s->System.out.printf("%s ", s));
}
}
--- code 1 --- Mr. Vijay Mr. Suresh --- code 2 --- 310 320 330
Example-3:
Find the examples of
limit method with parallel stream.
LimitDemo3.java
package com.concretepage;
import java.util.Arrays;
import java.util.List;
public class LimitDemo3 {
public static void main(String[] args) {
System.out.println("--- code 1 ---");
List<String> list = Arrays.asList("Varanasi", "Madurai", "Agartala");
list.parallelStream()
.limit(2)
.forEach(s->System.out.printf("%s ", s));
System.out.println("\n--- code 2 ---");
List<Integer> numList = Arrays.asList(41, 42, 43, 44);
numList.parallelStream()
.mapToInt(i -> i * 10)
.limit(3)
.forEach(s->System.out.printf("%s ", s));
}
}
--- code 1 --- Madurai Varanasi --- code 2 --- 420 410 430
