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Java 8 Streams - LongStream.findFirst Examples

Java 8 Streams Java Java API 

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Interface:

java.util.stream.LongStream

java.lang.AutoCloseableAutoCloseablejava.util.stream.BaseStreamBaseStreamjava.util.stream.LongStreamLongStreamLogicBig

Method:

OptionalLong findFirst()

This terminal-short-circuiting operation returns an OptionalLong describing the first element of this stream, or an empty OptionalLong if the stream is empty. If the stream has no encounter order, then any element may be returned.


Examples


package com.logicbig.example.longstream;

import java.util.stream.LongStream;

public class FindFirstExample {

    public static void main(String... args) {
        LongStream longStream = LongStream.of(1, 2, 3, 2, 5, 4);
        long l = longStream.findFirst()
                           .orElse(-1);
        System.out.println(l);
    }
}

Output

1




Parallel stream: 

package com.logicbig.example.longstream;

import java.util.stream.LongStream;

public class FindFirstExample2 {

    public static void main(String... args) {
        LongStream longStream = LongStream.of(1, 2, 3, 2, 5, 4);
        long l = longStream.parallel()
                           .findFirst()
                           .orElse(-1);
        System.out.println(l);
    }
}

Output

1




Parallel unordered stream: 

package com.logicbig.example.longstream;

import java.util.stream.LongStream;

public class FindFirstExample3 {

    public static void main(String... args) {
        LongStream longStream = LongStream.of(1, 2, 3, 2, 5, 4);
        long l = longStream.unordered()
                           .parallel()
                           .findFirst()
                           .orElse(-1);
        System.out.println(l);
    }
}

Output

1

See Also