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) {
    List<String> names = Arrays.asList("XML", "HTML", "Java", "Javascript", "CSS", "Static");

    Optional<String> firstZ = names.stream().filter(name -> name.startsWith("Z")).findFirst();
    if (firstZ.isPresent()) {
        System.out.println(firstZ.get());
    } else {//w ww . j av  a  2s.c  o  m
        System.out.println("No Z's found");
    }
}

From source file:Main.java

public static void main(String[] args) {
    List<String> names = Arrays.asList("Bob", "Tom", "Jeff", "Scott", "Jennifer", "Steve");

    Optional<String> firstS = names.stream().filter(name -> name.startsWith("S")).findFirst();
    System.out.println(firstS.orElse("None found"));

    Optional<String> firstZ = names.stream().filter(name -> name.startsWith("Z")).findFirst();
    if (firstZ.isPresent()) {
        System.out.println(firstZ.get());
    } else {//w  ww . j  a  va 2  s  . c om
        System.out.println("No Z's found");
    }
}

From source file:Main.java

public static void main(String[] args) {
    Optional<Integer> value = Optional.empty();

    System.out.println(value.orElse(42));
    System.out.println(value.isPresent());
    System.out.println(value.get());
}

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());
    String str = null;// w w  w .  j  av  a  2s.  c  o m
    // Optional.of(str);

    Optional<Integer> o = Optional.empty();
    System.out.println(o.isPresent());
    System.out.println(o.orElse(42));

    List<Integer> results = new ArrayList<>();
    Optional<Integer> second = Optional.of(3);
    second.ifPresent(results::add); // must operate via side-effects,
                                    // unfortunately...
    System.out.println(results);

    o = Optional.empty();
    System.out.println(o.orElse(42));

    o = Optional.of(42);
    System.out.println(o.get());

    o = Optional.empty();
    o.get();
}

From source file:Main.java

public static void main(String[] args) {
    List<Employee> persons = Employee.persons();
    // Find any male
    Optional<Employee> anyMale = persons.stream().filter(Employee::isMale).findAny();
    if (anyMale.isPresent()) {
        System.out.println("Any male:   " + anyMale.get());
    } else {//w w  w.ja va2  s  .  c  o m
        System.out.println("No male  found.");
    }
    // Find the first male
    Optional<Employee> firstMale = persons.stream().filter(Employee::isMale).findFirst();
    if (firstMale.isPresent()) {
        System.out.println("First male:   " + anyMale.get());
    } else {
        System.out.println("No male  found.");
    }
}

From source file:Main.java

public static void main(String[] args) {
    List<String> names = Arrays.asList("XML", "HTML", "CSS", "Javascript", "Java", "Static");

    Optional<String> longestName = names.stream()
            .reduce((name1, name2) -> name1.length() >= name2.length() ? name1 : name2);

    if (longestName.isPresent()) {
        System.out.println(longestName.get());
    } else {// ww  w  . j  a  va  2 s  . com
        System.out.println("WTF?");
    }

}

From source file:Main.java

public static void main(String[] args) {
    Optional<Employee> person = Employee.persons().stream()
            .max(Comparator.comparingDouble(Employee::getIncome));

    if (person.isPresent()) {
        System.out.println("Highest earner: " + person.get());
    } else {//w  w  w  .ja  va 2  s. c  o  m
        System.out.println("Could not  get   the   highest earner.");
    }
}

From source file:Main.java

public static void main(String[] args) {
    Optional<Employee> person = Employee.persons().stream()
            .reduce((p1, p2) -> p1.getIncome() > p2.getIncome() ? p1 : p2);
    if (person.isPresent()) {
        System.out.println("Highest earner: " + person.get());
    } else {//from  w  w w .j  ava 2  s .c  om
        System.out.println("Could not  get   the   highest earner.");
    }
}

From source file:com.ethercamp.harmony.Application.java

/**
 * Does one of:/* ww w .  j a va  2 s  .com*/
 * - start Harmony peer;
 * - perform action and exit on completion.
 */
public static void main(String[] args) throws Exception {
    final List<String> actions = asList("importBlocks");

    final Optional<String> foundAction = asList(args).stream().filter(arg -> actions.contains(arg)).findFirst();

    if (foundAction.isPresent()) {
        foundAction.ifPresent(action -> System.out.println("Performing action: " + action));
        Start.main(args);
        // system is expected to exit after action performed
    } else {
        if (!SystemProperties.getDefault().blocksLoader().equals("")) {
            SystemProperties.getDefault().setSyncEnabled(false);
            SystemProperties.getDefault().setDiscoveryEnabled(false);
        }

        ConfigurableApplicationContext context = SpringApplication.run(new Object[] { Application.class },
                args);

        Ethereum ethereum = context.getBean(Ethereum.class);

        if (!SystemProperties.getDefault().blocksLoader().equals("")) {
            ethereum.getBlockLoader().loadBlocks();
        }
    }
}

From source file:edu.jhu.hlt.concrete.ingesters.gigaword.GigawordGzProcessor.java

public static void main(String... args) {
    Thread.setDefaultUncaughtExceptionHandler(new LoggedUncaughtExceptionHandler());
    if (args.length != 2) {
        LOGGER.info("This program takes 2 arguments.");
        LOGGER.info("First: the path to a .gz file that is part of the English Gigaword v5 corpus.");
        LOGGER.info("Second: the path to the output file (a .tar.gz with communication files).");
        LOGGER.info("Example usage:");
        LOGGER.info("{} {} {}", GigawordGzProcessor.class.getName(), "/path/to/LDC/sgml/.gz",
                "/path/to/out.tar.gz");
        System.exit(1);//  w  ww  . j a  va 2  s.  c  o m
    }

    String inPathStr = args[0];
    String outPathStr = args[1];

    Path inPath = Paths.get(inPathStr);
    if (!Files.exists(inPath))
        LOGGER.error("Input path {} does not exist. Try again with the right path.", inPath.toString());

    Path outPath = Paths.get(outPathStr);
    Optional<Path> parent = Optional.ofNullable(outPath.getParent());
    // lambda does not allow caught exceptions.
    if (parent.isPresent()) {
        if (!Files.exists(outPath.getParent())) {
            LOGGER.info("Attempting to create output directory: {}", outPath.toString());
            try {
                Files.createDirectories(outPath);
            } catch (IOException e) {
                LOGGER.error("Caught exception creating output directory.", e);
            }
        }
    }

    GigawordDocumentConverter conv = new GigawordDocumentConverter();
    Iterator<Communication> iter = conv.gzToStringIterator(inPath);
    try (OutputStream os = Files.newOutputStream(outPath);
            BufferedOutputStream bos = new BufferedOutputStream(os, 1024 * 8 * 16);
            GzipCompressorOutputStream gout = new GzipCompressorOutputStream(bos);
            TarArchiver archiver = new TarArchiver(gout);) {
        while (iter.hasNext()) {
            Communication c = iter.next();
            LOGGER.info("Adding Communication {} [UUID: {}] to archive.", c.getId(),
                    c.getUuid().getUuidString());
            archiver.addEntry(new ArchivableCommunication(c));
        }
    } catch (IOException e) {
        LOGGER.error("Caught IOException during output.", e);
    }
}