Merge pull request #5813 from earth001/BAEL-2333a

BAEL-2333 Sample code

java-streams/pom.xml

@@ -1,5 +1,5 @@
 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
     <artifactId>java-streams</artifactId>
     <version>0.1.0-SNAPSHOT</version>
@@ -74,6 +74,11 @@
             <artifactId>aspectjweaver</artifactId>
             <version>${asspectj.version}</version>
         </dependency>
+        <dependency>
+            <groupId>pl.touk</groupId>
+            <artifactId>throwing-function</artifactId>
+            <version>${throwing-function.version}</version>
+        </dependency>
     </dependencies>
 
     <build>
@@ -108,8 +113,9 @@
         <protonpack.version>1.15</protonpack.version>
         <streamex.version>0.6.5</streamex.version>
         <joda.version>2.10</joda.version>
+        <throwing-function.version>1.3</throwing-function.version>
         <!-- testing -->
-        <assertj.version>3.6.1</assertj.version>
+        <assertj.version>3.11.1</assertj.version>
         <asspectj.version>1.8.9</asspectj.version>
     </properties>
 </project>

java-streams/src/main/java/com/baeldung/stream/filter/Customer.java

@@ -0,0 +1,55 @@
+package com.baeldung.stream.filter;
+
+import javax.net.ssl.HttpsURLConnection;
+import java.io.IOException;
+import java.net.HttpURLConnection;
+import java.net.URL;
+
+public class Customer {
+    private String name;
+    private int points;
+    private String profilePhotoUrl;
+
+    public Customer(String name, int points) {
+        this(name, points, "");
+    }
+
+    public Customer(String name, int points, String profilePhotoUrl) {
+        this.name = name;
+        this.points = points;
+        this.profilePhotoUrl = profilePhotoUrl;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public int getPoints() {
+        return points;
+    }
+
+    public boolean hasOver(int points) {
+        return this.points > points;
+    }
+
+    public boolean hasOverThousandPoints() {
+        return this.points > 100;
+    }
+
+    public boolean hasValidProfilePhoto() throws IOException {
+        URL url = new URL(this.profilePhotoUrl);
+        HttpsURLConnection connection = (HttpsURLConnection) url.openConnection();
+        return connection.getResponseCode() == HttpURLConnection.HTTP_OK;
+    }
+
+    public boolean hasValidProfilePhotoWithoutCheckedException() {
+        try {
+            URL url = new URL(this.profilePhotoUrl);
+            HttpsURLConnection connection = (HttpsURLConnection) url.openConnection();
+            return connection.getResponseCode() == HttpURLConnection.HTTP_OK;
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+}

java-streams/src/test/java/com/baeldung/stream/filter/StreamFilterUnitTest.java

@@ -0,0 +1,159 @@
+package com.baeldung.stream.filter;
+
+import org.junit.jupiter.api.Test;
+import pl.touk.throwing.ThrowingPredicate;
+import pl.touk.throwing.exception.WrappedException;
+
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Optional;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.AssertionsForClassTypes.assertThatThrownBy;
+
+public class StreamFilterUnitTest {
+
+    @Test
+    public void givenListOfCustomers_whenFilterByPoints_thenGetTwo() {
+        Customer john = new Customer("John P.", 15);
+        Customer sarah = new Customer("Sarah M.", 200);
+        Customer charles = new Customer("Charles B.", 150);
+        Customer mary = new Customer("Mary T.", 1);
+        List<Customer> customers = Arrays.asList(john, sarah, charles, mary);
+
+        List<Customer> customersWithMoreThan100Points = customers
+          .stream()
+          .filter(c -> c.getPoints() > 100)
+          .collect(Collectors.toList());
+
+        assertThat(customersWithMoreThan100Points).hasSize(2);
+        assertThat(customersWithMoreThan100Points).contains(sarah, charles);
+    }
+
+    @Test
+    public void givenListOfCustomers_whenFilterByPointsAndName_thenGetOne() {
+        Customer john = new Customer("John P.", 15);
+        Customer sarah = new Customer("Sarah M.", 200);
+        Customer charles = new Customer("Charles B.", 150);
+        Customer mary = new Customer("Mary T.", 1);
+        List<Customer> customers = Arrays.asList(john, sarah, charles, mary);
+
+        List<Customer> charlesWithMoreThan100Points = customers
+          .stream()
+          .filter(c -> c.getPoints() > 100 && c
+            .getName()
+            .startsWith("Charles"))
+          .collect(Collectors.toList());
+
+        assertThat(charlesWithMoreThan100Points).hasSize(1);
+        assertThat(charlesWithMoreThan100Points).contains(charles);
+    }
+
+    @Test
+    public void givenListOfCustomers_whenFilterByMethodReference_thenGetTwo() {
+        Customer john = new Customer("John P.", 15);
+        Customer sarah = new Customer("Sarah M.", 200);
+        Customer charles = new Customer("Charles B.", 150);
+        Customer mary = new Customer("Mary T.", 1);
+        List<Customer> customers = Arrays.asList(john, sarah, charles, mary);
+
+        List<Customer> customersWithMoreThan100Points = customers
+          .stream()
+          .filter(Customer::hasOverThousandPoints)
+          .collect(Collectors.toList());
+
+        assertThat(customersWithMoreThan100Points).hasSize(2);
+        assertThat(customersWithMoreThan100Points).contains(sarah, charles);
+    }
+
+    @Test
+    public void givenListOfCustomersWithOptional_whenFilterBy100Points_thenGetTwo() {
+        Optional<Customer> john = Optional.of(new Customer("John P.", 15));
+        Optional<Customer> sarah = Optional.of(new Customer("Sarah M.", 200));
+        Optional<Customer> mary = Optional.of(new Customer("Mary T.", 300));
+        List<Optional<Customer>> customers = Arrays.asList(john, sarah, Optional.empty(), mary, Optional.empty());
+
+        List<Customer> customersWithMoreThan100Points = customers
+          .stream()
+          .flatMap(c -> c
+            .map(Stream::of)
+            .orElseGet(Stream::empty))
+          .filter(Customer::hasOverThousandPoints)
+          .collect(Collectors.toList());
+
+        assertThat(customersWithMoreThan100Points).hasSize(2);
+        assertThat(customersWithMoreThan100Points).contains(sarah.get(), mary.get());
+    }
+
+    @Test
+    public void givenListOfCustomers_whenFilterWithCustomHandling_thenThrowException() {
+        Customer john = new Customer("John P.", 15, "https://images.unsplash.com/photo-1543320485-d0d5a49c2b2e");
+        Customer sarah = new Customer("Sarah M.", 200);
+        Customer charles = new Customer("Charles B.", 150);
+        Customer mary = new Customer("Mary T.", 1, "https://images.unsplash.com/photo-1543297057-25167dfc180e");
+        List<Customer> customers = Arrays.asList(john, sarah, charles, mary);
+
+        assertThatThrownBy(() -> customers
+          .stream()
+          .filter(Customer::hasValidProfilePhotoWithoutCheckedException)
+          .count()).isInstanceOf(RuntimeException.class);
+    }
+
+    @Test
+    public void givenListOfCustomers_whenFilterWithThrowingFunction_thenThrowException() {
+        Customer john = new Customer("John P.", 15, "https://images.unsplash.com/photo-1543320485-d0d5a49c2b2e");
+        Customer sarah = new Customer("Sarah M.", 200);
+        Customer charles = new Customer("Charles B.", 150);
+        Customer mary = new Customer("Mary T.", 1, "https://images.unsplash.com/photo-1543297057-25167dfc180e");
+        List<Customer> customers = Arrays.asList(john, sarah, charles, mary);
+
+        assertThatThrownBy(() -> customers
+          .stream()
+          .filter((ThrowingPredicate.unchecked(Customer::hasValidProfilePhoto)))
+          .collect(Collectors.toList())).isInstanceOf(WrappedException.class);
+    }
+
+    @Test
+    public void givenListOfCustomers_whenFilterWithTryCatch_thenGetTwo() {
+        Customer john = new Customer("John P.", 15, "https://images.unsplash.com/photo-1543320485-d0d5a49c2b2e");
+        Customer sarah = new Customer("Sarah M.", 200);
+        Customer charles = new Customer("Charles B.", 150);
+        Customer mary = new Customer("Mary T.", 1, "https://images.unsplash.com/photo-1543297057-25167dfc180e");
+        List<Customer> customers = Arrays.asList(john, sarah, charles, mary);
+
+        List<Customer> customersWithValidProfilePhoto = customers
+          .stream()
+          .filter(c -> {
+              try {
+                  return c.hasValidProfilePhoto();
+              } catch (IOException e) {
+                  //handle exception
+              }
+              return false;
+          })
+          .collect(Collectors.toList());
+
+        assertThat(customersWithValidProfilePhoto).hasSize(2);
+        assertThat(customersWithValidProfilePhoto).contains(john, mary);
+    }
+
+    @Test
+    public void givenListOfCustomers_whenFilterWithTryCatchAndRuntime_thenThrowException() {
+        List<Customer> customers = Arrays.asList(new Customer("John P.", 15, "https://images.unsplash.com/photo-1543320485-d0d5a49c2b2e"), new Customer("Sarah M.", 200), new Customer("Charles B.", 150),
+          new Customer("Mary T.", 1, "https://images.unsplash.com/photo-1543297057-25167dfc180e"));
+
+        assertThatThrownBy(() -> customers
+          .stream()
+          .filter(c -> {
+              try {
+                  return c.hasValidProfilePhoto();
+              } catch (IOException e) {
+                  throw new RuntimeException(e);
+              }
+          })
+          .collect(Collectors.toList())).isInstanceOf(RuntimeException.class);
+    }
+}