optional examples (#2537)

2017-08-31 13:06:37 +03:00
parent 2f3e36405a
commit 49acba206c
13 changed files with 583 additions and 0 deletions
@@ -0,0 +1,166 @@
+package com.stackify.optional;
+
+import static org.junit.Assert.*;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.NoSuchElementException;
+import java.util.Optional;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.junit.Test;
+
+public class OptionalTest {
+
+    private User user;
+
+    private Logger logger = LogManager.getLogger(OptionalTest.class);
+
+    @Test(expected = NullPointerException.class)
+    public void testNull() {
+        String isocode = user.getAddress().getCountry().getIsocode().toUpperCase();
+    }
+
+    @Test
+    public void test() {
+
+        if (user != null) {
+            Address address = user.getAddress();
+            if (address != null) {
+                Country country = address.getCountry();
+                if (country != null) {
+                    String isocode = country.getIsocode();
+                    if (isocode != null) {
+                        isocode = isocode.toUpperCase();
+                    }
+                }
+            }
+        }
+
+    }
+
+    @Test(expected = NoSuchElementException.class)
+    public void whenCreateEmptyOptional_thenNull() {
+        Optional<User> emptyOpt = Optional.empty();
+        emptyOpt.get();
+    }
+
+    @Test(expected = NullPointerException.class)
+    public void whenCreateOfEmptyOptional_thenNullPointerException() {
+        Optional<User> opt = Optional.of(user);
+    }
+
+    @Test
+    public void whenCreateOfNullableOptional_thenOk() {
+        String name = "John";
+        Optional<String> opt = Optional.ofNullable(name);
+        assertEquals("John", opt.get());
+    }
+
+    @Test
+    public void whenCheckIsPresent_thenOk() {
+        user = new User("john@gmail.com", "1234");
+        Optional<User> opt = Optional.ofNullable(user);
+        assertTrue(opt.isPresent());
+
+        assertEquals(user.getEmail(), opt.get().getEmail());
+    }
+
+    @Test
+    public void whenCheckIfPresent_thenOk() {
+        user = new User("john@gmail.com", "1234");
+        Optional<User> opt = Optional.ofNullable(user);
+        assertTrue(opt.isPresent());
+
+        opt.ifPresent(u -> assertEquals(user.getEmail(), u.getEmail()));
+    }
+
+    @Test
+    public void whenEmptyValue_thenReturnDefault() {
+        User user = null;
+        User user2 = new User("anna@gmail.com", "1234");
+        User result = Optional.ofNullable(user).orElse(user2);
+
+        assertEquals("anna@gmail.com", result.getEmail());
+    }
+
+    @Test
+    public void whenValueNotNull_thenIgnoreDefault() {
+        User user = new User("john@gmail.com", "1234");
+        User user2 = new User("anna@gmail.com", "1234");
+        User result = Optional.ofNullable(user).orElse(user2);
+
+        assertEquals("john@gmail.com", result.getEmail());
+    }
+
+    @Test
+    public void whenSetDefaultOrElseGet_thenOk() {
+        User user = null;
+        User user2 = new User("anna@gmail.com", "1234");
+        User result = Optional.ofNullable(user).orElseGet(() -> user2);
+
+        assertEquals("anna@gmail.com", result.getEmail());
+    }
+
+    @Test
+    public void givenPresentValue_whenCompare_thenOk() {
+        User user = new User("john@gmail.com", "1234");
+        logger.info("Using orElse");
+        User result = Optional.ofNullable(user).orElse(createNewUser());
+        logger.info("Using orElseGet");
+        User result2 = Optional.ofNullable(user).orElseGet(() -> createNewUser());
+    }
+
+    private User createNewUser() {
+        logger.info("Creating New User");
+        return new User("extra@gmail.com", "1234");
+    }
+
+    @Test
+    public void givenEmptyValue_whenCompare_thenOk() {
+        User user = null;
+        logger.info("Using orElse");
+        User result = Optional.ofNullable(user).orElse(createNewUser());
+        logger.info("Using orElseGet");
+        User result2 = Optional.ofNullable(user).orElseGet(() -> createNewUser());
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void whenThrowException_thenOk() {
+        User result = Optional.ofNullable(user).orElseThrow(() -> new IllegalArgumentException());
+    }
+
+    @Test
+    public void whenMap_thenOk() {
+        user = new User("anna@gmail.com", "1234");
+        String email = Optional.ofNullable(user).map(u -> u.getEmail()).orElse("default@gmail.com");
+        assertEquals(email, user.getEmail());
+
+    }
+
+    @Test
+    public void whenFlatMap_thenOk() {
+        user = new User("anna@gmail.com", "1234");
+        user.setPosition("Developer");
+        String position = Optional.ofNullable(user).flatMap(u -> u.getPosition()).orElse("default");
+        assertEquals(position, user.getPosition().get());
+
+    }
+
+    @Test
+    public void whenFilter_thenOk() {
+        user = new User("anna@gmail.com", "1234");
+        Optional<User> result = Optional.ofNullable(user).filter(u -> u.getEmail() != null && u.getEmail().contains("@"));
+
+        assertTrue(result.isPresent());
+    }
+
+    @Test
+    public void whenStream_thenOk() {
+        List<User> users = new ArrayList<>();
+        User user = users.stream().findFirst().orElse(new User("default", "1234"));
+        assertEquals(user.getEmail(), "default");
+    }
+
+}
@@ -0,0 +1,36 @@
+package com.stackify.optional.chaining;
+
+import static org.junit.Assert.*;
+
+import java.util.Optional;
+
+import org.junit.Test;
+
+public class OptionalChainingTest {
+
+    @Test
+    public void whenChaining_thenOk() {
+        User user = new User("anna@gmail.com", "1234");
+
+        String result = Optional.ofNullable(user)
+                .flatMap(u -> u.getAddress())
+                .flatMap(a -> a.getCountry())
+                .map(c -> c.getIsocode())
+                .orElse("default");
+
+        assertEquals(result, "default");
+    }
+    
+    @Test
+    public void whenChainingWithMethodReferences_thenOk() {
+        User user = new User("anna@gmail.com", "1234");
+
+        String result = Optional.ofNullable(user)
+                .flatMap(User::getAddress)
+                .flatMap(Address::getCountry)
+                .map(Country::getIsocode)
+                .orElse("default");
+
+        assertEquals(result, "default");
+    }
+}