BAEL-6154: Migrate from Java 8 to Java 17 + tests (#13474)

core-java-modules/core-java-17/src/main/java/com/baeldung/java8to17/Address.java

@@ -0,0 +1,40 @@
+package com.baeldung.java8to17;
+
+public class Address {
+
+    private String street;
+    private String city;
+    private String pin;
+
+    public Address(String street, String city, String pin) {
+        super();
+        this.street = street;
+        this.city = city;
+        this.pin = pin;
+    }
+
+    public String getStreet() {
+        return street;
+    }
+
+    public void setStreet(String street) {
+        this.street = street;
+    }
+
+    public String getCity() {
+        return city;
+    }
+
+    public void setCity(String city) {
+        this.city = city;
+    }
+
+    public String getPin() {
+        return pin;
+    }
+
+    public void setPin(String pin) {
+        this.pin = pin;
+    }
+
+}

core-java-modules/core-java-17/src/main/java/com/baeldung/java8to17/Circle.java

@@ -0,0 +1,4 @@
+package com.baeldung.java8to17;
+
+public record Circle(double radius) implements Shape {
+}

core-java-modules/core-java-17/src/main/java/com/baeldung/java8to17/Person.java

@@ -0,0 +1,30 @@
+package com.baeldung.java8to17;
+
+public class Person {
+
+    private String name;
+    private Address address;
+
+    public Person(String name, Address address) {
+        super();
+        this.name = name;
+        this.address = address;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public Address getAddress() {
+        return address;
+    }
+
+    public void setAddress(Address address) {
+        this.address = address;
+    }
+
+}

core-java-modules/core-java-17/src/main/java/com/baeldung/java8to17/Rectangle.java

@@ -0,0 +1,4 @@
+package com.baeldung.java8to17;
+
+public record Rectangle(double length, double width) implements Shape {
+}

core-java-modules/core-java-17/src/main/java/com/baeldung/java8to17/Shape.java

@@ -0,0 +1,5 @@
+package com.baeldung.java8to17;
+
+public interface Shape {
+
+}

core-java-modules/core-java-17/src/main/java/com/baeldung/java8to17/Student.java

@@ -0,0 +1,5 @@
+package com.baeldung.java8to17;
+
+public record Student(int rollNo, String name) {
+
+}

core-java-modules/core-java-17/src/test/java/com/baeldung/java17/Java8to17ExampleUnitTest.java

@@ -0,0 +1,87 @@
+package com.baeldung.java17;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.Assert.assertThrows;
+
+import java.util.Arrays;
+
+import org.junit.jupiter.api.Test;
+
+import com.baeldung.java8to17.Address;
+import com.baeldung.java8to17.Circle;
+import com.baeldung.java8to17.Person;
+import com.baeldung.java8to17.Rectangle;
+import com.baeldung.java8to17.Student;
+
+public class Java8to17ExampleUnitTest {
+
+    @Test
+    void givenMultiLineText_whenUsingTextBlock_thenStringIsReturned() {
+        String value = """
+            This is a
+            Multi-line
+            Text
+            """;
+        
+        assertThat(value).isEqualTo("This is a\nMulti-line\nText\n");
+    }
+    
+    @Test
+    void givenString_whenUsingUtilFunctions_thenReturnsExpectedResult() {
+        assertThat("  ".isBlank());
+        assertThat("Twinkle ".repeat(2)).isEqualTo("Twinkle Twinkle ");
+        assertThat("Format Line".indent(4)).isEqualTo("    Format Line\n");
+        assertThat("Line 1 \n Line2".lines()).asList().size().isEqualTo(2);
+        assertThat(" Text with white spaces   ".strip()).isEqualTo("Text with white spaces");
+        assertThat("Car, Bus, Train".transform(s1 -> Arrays.asList(s1.split(","))).get(0)).isEqualTo("Car");
+    }
+    
+    @Test
+    void givenDataModel_whenUsingRecordType_thenBehavesLikeDTO() {
+        Student student = new Student(10, "Priya");
+        Student student2 = new Student(10, "Priya");
+        
+        assertThat(student.rollNo()).isEqualTo(10);
+        assertThat(student.name()).isEqualTo("Priya");
+        assertThat(student.equals(student2));
+        assertThat(student.hashCode()).isEqualTo(student2.hashCode());
+    }
+    
+    @Test 
+    void givenObject_whenThrowingNPE_thenReturnsHelpfulMessage() {
+        Person student = new Person("Lakshmi", new Address("35, West Street", null, null));
+        
+        Exception exception = assertThrows(NullPointerException.class, () -> {
+            student.getAddress().getCity().toLowerCase();
+        });
+        
+        assertThat(exception.getMessage()).isEqualTo(
+            "Cannot invoke \"String.toLowerCase()\" because the return value of \"com.baeldung.java8to17.Address.getCity()\" is null");
+    }
+    
+    @Test 
+    void givenGenericObject_whenUsingPatternMatching_thenReturnsTargetType() {
+        String city = null;
+        Object obj = new Address("35, West Street", "Chennai", "6000041");
+
+        if (obj instanceof Address address) {
+            city = address.getCity();
+        }
+        
+        assertThat(city).isEqualTo("Chennai");
+    }
+    
+    @Test 
+    void givenGenericObject_whenUsingSwitchExpression_thenPatternMatchesRightObject() {
+        Object shape = new Rectangle(10, 20);
+        
+        double circumference = switch (shape) {
+            case Rectangle r -> 2 * r.length() + 2 * r.width();
+            case Circle c -> 2 * c.radius() * Math.PI;
+            default -> throw new IllegalArgumentException("Unknown shape");
+        };
+        
+        assertThat(circumference).isEqualTo(60);
+    }
+
+}