Eakterina Son (Optional)

src/test/java/option/OptionalExample.java

@@ -1,15 +1,26 @@
 package option;
 
+
 import org.junit.Test;
 
 import java.util.Optional;
 import java.util.concurrent.ThreadLocalRandom;
+import java.util.function.BiFunction;
 import java.util.function.Function;
+import java.util.function.Predicate;
+import java.util.function.Supplier;
 
 import static org.junit.Assert.assertEquals;
 
 public class OptionalExample {
 
+    //не используя не final переменные
+    //не используя isPresent() и get()
+    //использовать map() и flatMap()
+    public static <T1, T2, R> Optional<R> zipMap(Optional<T1> o1, Optional<T2> o2, BiFunction<T1, T2, R> f){
+        throw new UnsupportedOperationException();
+    }
+
     @Test
     public void get() {
         final Optional<String> o1 = Optional.empty();
@@ -21,6 +32,8 @@ public void get() {
         o1.orElseThrow(() -> new UnsupportedOperationException());
     }
 
+
+
     @Test
     public void ifPresent() {
         final Optional<String> o1 = getOptional();
@@ -50,6 +63,102 @@ public void map() {
         assertEquals(expected, actual);
     }
 
+    @Test
+    public void filter() {
+        final Optional<String> o1 = getOptional();
+
+        final Predicate<String> isEmpty = String::isEmpty;
+
+        final Optional<String> expected = o1.filter(isEmpty);
+
+        final Optional<String> actual;
+        if (o1.isPresent()) {
+            if(isEmpty.test(o1.get())){
+                actual = Optional.empty();
+            }
+            else{
+                actual = Optional.of(o1.get());
+            }
+        } else {
+            actual = Optional.empty();
+        }
+        assertEquals(expected, actual);
+    }
+
+
+
+    @Test
+    public void flatMap() {
+
+        final Optional<String> o1 = getOptional();
+
+        final Function<String, Optional<Integer>> getLength = s -> Optional.of(s.length());
+
+        final Optional<Integer> expected = o1.flatMap(getLength);
+
+        final Optional<Integer> actual;
+        if (o1.isPresent()) {
+            actual = getLength.apply(o1.get());
+        } else {
+            actual = Optional.empty();
+        }
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    public void orElse() {
+
+        final Optional<String> o1 = getOptional();
+
+        final String aNull = "null";
+        final Optional<String> expected = Optional.of(o1.orElse(aNull));
+
+        final Optional<String> actual;
+        if (o1.isPresent()) {
+            actual = Optional.of(o1.get());
+        } else {
+            actual = Optional.of(aNull);
+        }
+        assertEquals(expected, actual);
+    }
+    @Test
+    public void orElseGet() {
+
+        final Optional<String> o1 = getOptional();
+        final Supplier<String> s = () -> "null";
+
+        final Optional<String> expected = Optional.of(o1.orElseGet(s));
+
+        final Optional<String> actual;
+        if (o1.isPresent()) {
+            actual = Optional.of(o1.get());
+        } else {
+            actual = Optional.of(s.get());
+        }
+        assertEquals(expected, actual);
+    }
+    @Test
+    public void orElseThrow() {
+
+        final Optional<String> o1 = getOptional();
+        final String expectedMessage = "Exception was thrown";
+        final Supplier<UnsupportedOperationException> ex =() -> new UnsupportedOperationException("Exception was thrown");
+
+        final Optional<String> actual;
+        try{
+            final Optional<String> expected = Optional.of(o1.orElseThrow(ex));
+            if (o1.isPresent()) {
+                actual = Optional.of(o1.get());
+                assertEquals(expected, actual);
+            }
+        }
+        catch (UnsupportedOperationException e){
+            System.out.println(e.getMessage());
+            assertEquals(expectedMessage, e.getMessage());
+        }
+
+    }
+
     private Optional<String> getOptional() {
         return ThreadLocalRandom.current().nextBoolean()
             ? Optional.empty()