We've already seen many methods of IntStream API.
This is used to get the first element from the stream. In this article, We will see its syntax, example program, and internal implementation.
API Note:
Returns an OptionalInt describing the first element of this stream, or an empty OptionalInt if the stream is empty. If the stream has no encounter order, then any element may be returned.
Returns an OptionalInt describing the first element of this stream, or an empty OptionalInt if the stream is empty. If the stream has no encounter order, then any element may be returned.
This method returns the first element from the integer stream. Returns OptionalInt object which holds the value of the first element.
Syntax:
OptionalInt findFirst()
Returns OptionalInt object.
This is part of short-circuiting terminal operation.
If the stream is empty then it returns empty OptionalInt object.
Example:
This is part of short-circuiting terminal operation.
If the stream is empty then it returns empty OptionalInt object.
Example:
package com.java.w3schools.blog.java8.stream.intstream;
import java.util.OptionalInt;
import java.util.stream.IntStream;
/**
*
* Java 8 IntStream findFirst() Method Example
*
* @author venkateshn
*
*/
public class IntStreamFindFirstExample {
public static void main(String[] args) {
IntStream values = IntStream.of(1, 2, 3, 4, 5, 6, 7, 8, 9);
OptionalInt firstValue = values.findFirst();
if (firstValue.isPresent()) {
System.out.println("first value : " + firstValue.getAsInt());
} else {
System.out.println("No value is present");
}
}
}
first value : 1
API note saying if the stream is empty then it returns empty OptionalInt instance. We will demonstrate with the below example.
package com.java.w3schools.blog.java8.stream.intstream;
import java.util.OptionalInt;
import java.util.stream.IntStream;
/**
*
* Java 8 empyt IntStream findFirst() Method Example
*
* @author venkateshn
*
*/
public class FindFirstEmptyExample {
public static void main(String[] args) {
IntStream emptyStream = IntStream.empty();
OptionalInt emptyOptionalInt = emptyStream.findFirst();
if (emptyOptionalInt.isPresent()) {
System.out.println("Value is present");
} else {
System.out.println("First value is not present because stream is blank.");
}
}
}
Output:
4. findFirst() to get the first even number
Output:
5. Conclusion
In this article, We've seen how to get the first value from the IntStream using findFirst().
Many example programs are shown on findFirst() method.
This method returns OptionalInt object and if stream empty then it returns empty OptionalInt object.
All examples shown in this article are over GitHub.
API Ref
First value is not present because stream is blank.
package com.java.w3schools.blog.java8.stream.intstream;
import java.util.OptionalInt;
import java.util.stream.IntStream;
/**
*
* Java 8 empyt IntStream findFirst() Method Example
*
* @author venkateshn
*
*/
public class FindFirstParrellExample {
public static void main(String[] args) {
IntStream values = IntStream.of(1, 2, 3, 4, 5, 6, 7, 8, 9).parallel();
OptionalInt optionalInt = values.filter(value -> value % 2 == 0).findFirst();
if (optionalInt.isPresent()) {
System.out.println("First value is " + optionalInt.getAsInt());
} else {
System.out.println("First value is not present because stream is blank.");
}
}
}
Output:
First value is 2
In this article, We've seen how to get the first value from the IntStream using findFirst().
Many example programs are shown on findFirst() method.
This method returns OptionalInt object and if stream empty then it returns empty OptionalInt object.
All examples shown in this article are over GitHub.
API Ref
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