OptionalExampleTest.java

package com.insightfullogic.java8.examples.chapter4;

import org.junit.Test;

import java.util.Optional;

import static org.junit.Assert.*;

public class OptionalExampleTest {

    @Test
    public void examples() {
// BEGIN value_creation
Optional<String> a = Optional.of("a");
assertEquals("a", a.get());
// END value_creation

// BEGIN is_present
Optional emptyOptional = Optional.empty();
Optional alsoEmpty = Optional.ofNullable(null);

assertFalse(emptyOptional.isPresent());

// a is defined above
assertTrue(a.isPresent());
// END is_present

// BEGIN orElse
assertEquals("b", emptyOptional.orElse("b"));
assertEquals("c", emptyOptional.orElseGet(() -> "c"));
// END orElse
    }

}