Example usage for java.util Optional isPresent

Introduction

In this page you can find the example usage for java.util Optional isPresent.

Prototype

public boolean isPresent()

Source Link

Document

If a value is present, returns true , otherwise false .

Usage

From source file:Main.java

public static void main(String[] args) {
    Optional<String> optional = Optional.of("bam");

    optional.isPresent(); // true
    optional.get(); // "bam"
    optional.orElse("fallback"); // "bam"

    optional.ifPresent((s) -> System.out.println(s.charAt(0))); // "b"
}

From source file:Main.java

public static void main(String[] args) {
    List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);
    Optional<Integer> o = numbers.stream().findAny();
    if (o.isPresent()) {
        System.out.println(o.get());
    } else {//  w  w  w .  j  ava2 s.  com
        System.out.println("no value");
    }

}

From source file:Main.java

public static void main(String[] args) {
    List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);
    Optional<Integer> o = numbers.stream().findFirst();
    if (o.isPresent()) {
        System.out.println(o.get());
    } else {/*from  w  w w.j a v a2s  .  com*/
        System.out.println("no value");
    }

}

From source file:Main.java

public static void main(String[] args) {
    Optional<String> value = Optional.of("some value");
    System.out.println(value.isPresent());
    System.out.println(value.get());
}

From source file:Main.java

public static void main(String[] args) {
    List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);
    Optional<Integer> sum = numbers.stream().reduce(Integer::sum);
    if (sum.isPresent()) {
        System.out.println(sum.get());
    } else {/* ww w . j  a v a 2s  . c o  m*/
        System.out.println("noValue ");
    }

}

From source file:Main.java

public static void main(String[] args) {
    List<String> stringList = Arrays.asList("2", "1", "3", "4");

    Optional<String> m = stringList.stream().min(Comparator.reverseOrder());
    if (m.isPresent()) {
        System.out.println(m.get());
    } else {//from   www.jav a2 s.com
        System.out.println("No Value");
    }

}

From source file:Main.java

public static void main(String[] args) {
    List<String> stringList = Arrays.asList("2", "1", "3", "4");

    Optional<String> m = stringList.stream().max(Comparator.reverseOrder());
    if (m.isPresent()) {
        System.out.println(m.get());
    } else {/* w w w . j  av  a  2 s  . c  o  m*/
        System.out.println("No Value");
    }

}

From source file:Main.java

public static void main(String[] args) {
    Stream<String> s = Stream.of("1", "2", "3");

    Optional<String> o = s.collect(Collectors.maxBy(Comparator.reverseOrder()));

    if (o.isPresent()) {
        System.out.println(o.get());
    } else {//from  ww  w.  j a v a2  s.  c o  m
        System.out.println("no value");
    }

}

From source file:Main.java

public static void main(String[] args) {
    Stream<String> s = Stream.of("1", "2", "3");

    Optional<String> o = s.collect(Collectors.minBy(Comparator.reverseOrder()));

    if (o.isPresent()) {
        System.out.println(o.get());
    } else {//from  www  . j av  a2 s .c om
        System.out.println("no value");
    }

}

From source file:Main.java

public static void main(String[] args) {
    Optional<Integer> max = Stream.of(1, 2, 3, 4, 5).reduce(Integer::max);

    if (max.isPresent()) {
        System.out.println("max = " + max.get());
    } else {/*from   www.  j a  v a2s  .co m*/
        System.out.println("max is not  defined.");
    }

    max = Stream.<Integer>empty().reduce(Integer::max);
    if (max.isPresent()) {
        System.out.println("max = " + max.get());
    } else {
        System.out.println("max is not  defined.");
    }

}