antipatterns

antipatterns/.gitignore

+target/
+.classpath
+.project

antipatterns/pom.xml

+<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+  	<modelVersion>4.0.0</modelVersion>
+  	<groupId>it1901</groupId>
+  	<artifactId>antipatterns</artifactId>
+  	<version>0.0.1-SNAPSHOT</version>
+  
+	<dependencies>
+
+		<!-- Test with JUnit5 -->
+		<dependency>
+			<groupId>org.junit.jupiter</groupId>
+			<artifactId>junit-jupiter-api</artifactId>
+			<version>5.4.2</version>
+			<scope>test</scope>
+		</dependency>
+		<dependency>
+			<groupId>org.junit.jupiter</groupId>
+			<artifactId>junit-jupiter-engine</artifactId>
+			<version>5.4.2</version>
+			<scope>test</scope>
+		</dependency>		
+	</dependencies>
+
+	<build>
+		<plugins>
+			<!-- Compiling code -->
+			<plugin>
+				<artifactId>maven-compiler-plugin</artifactId>
+				<version>3.8.1</version>
+				<configuration>
+					<encoding>UTF-8</encoding>
+					<release>13</release>
+				</configuration>
+			</plugin>
+			<plugin>
+				<groupId>org.apache.maven.plugins</groupId>
+				<artifactId>maven-surefire-plugin</artifactId>
+                <version>3.0.0-M5</version>
+                <!-- 
+                <configuration>
+                    <argLine>${argLine} dash dash add-exports javafx.graphics/com.sun.javafx.application=ALL-UNNAMED</argLine>
+                </configuration>
+                 -->
+			</plugin>
+		</plugins>
+  	</build>
+</project>
\ No newline at end of file

antipatterns/src/main/java/antipatterns/DataClassWithEffectivelyFinalFields.java

+package antipatterns;
+
+public class DataClassWithEffectivelyFinalFields {
+
+  private final String name; // should be final
+  private final int number; // should be final
+
+  public DataClassWithEffectivelyFinalFields(final String name, final int number) {
+    this.name = name;
+    this.number = number;
+  }
+
+  public String getName() {
+    return name;
+  }
+
+  public int getNumber() {
+    return number;
+  }
+}

antipatterns/src/main/java/antipatterns/DataClassWithLittleLogic.java

+package antipatterns;
+
+// ok, but see the test
+public class DataClassWithLittleLogic {
+
+  private String name;
+  private int number;
+
+  public DataClassWithLittleLogic(final String name, final int number) {
+    this.name = name;
+    this.number = number;
+  }
+
+  @Override
+  public String toString() {
+    return String.format("[DataClassWithLittleLogic name=%s number=%s]", name, number);
+  }
+
+  public DataClassWithLittleLogic() {
+  }
+
+  public String getName() {
+    return name;
+  }
+  public void setName(final String name) {
+    this.name = name;
+  }
+
+  public int getNumber() {
+    return number;
+  }
+  public void setNumber(final int number) {
+    this.number = number;
+  }
+}

antipatterns/src/main/java/antipatterns/DataClassWithValidation.java

+package antipatterns;
+
+// see DataClassWithValidationTest
+public class DataClassWithValidation {
+
+  private String name;
+
+  public DataClassWithValidation(final String name) {
+    // should use setName to ensure validation logic is run
+    this.name = name;
+  }
+
+  public DataClassWithValidation() {
+  }
+
+  public String getName() {
+    return name;
+  }
+  public void setName(final String name) {
+    if (name.startsWith(" ")) {
+      // should rather use trim() or strip() and check the length
+      throw new IllegalArgumentException("Name cannot begin with blank");
+    }
+    this.name = name;
+  }
+}

antipatterns/src/main/java/antipatterns/NonEncapsulatedList.java

+package antipatterns;
+
+import java.util.Collection;
+import java.util.Iterator;
+
+public class NonEncapsulatedList implements Iterable<String> {
+
+  private final Collection<String> names;
+
+  public NonEncapsulatedList(final Collection<String> names) {
+    this.names = names;
+  }
+
+  public Collection<String> getNames() {
+    return names;
+  }
+
+  public Iterator<String> iterator() {
+    return names.iterator();
+  }
+}

antipatterns/src/test/java/antipatterns/DataClassWithLittleLogicTest.java

+package antipatterns;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+public class DataClassWithLittleLogicTest {
+
+  private DataClassWithLittleLogic instance1, instance2;
+
+  @BeforeEach
+  public void setup() {
+    instance1 = new DataClassWithLittleLogic();
+    instance2 = new DataClassWithLittleLogic("High", 5);
+  }
+
+  @Test
+  public void testConstructor() {
+    Assertions.assertEquals("High", instance2.getName());
+  }
+
+  @Test
+  public void testToString() {
+    Assertions.assertEquals("[DataClassWithLittleLogic name=High number=5]", instance2.toString());
+  }
+
+  @Test
+  public void testSetName() {
+    instance1.setName("Low");
+    Assertions.assertEquals("Low", instance1.getName());
+  }
+}

antipatterns/src/test/java/antipatterns/DataClassWithValidationTest.java

+package antipatterns;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+public class DataClassWithValidationTest {
+
+  @Test
+  public void testSetName() {
+    try {
+      new DataClassWithValidation(" name starting with blank");
+      Assertions.fail("Should throw IllegalArgumentException");
+    } catch (final IllegalArgumentException iae) {
+    } catch (final Exception iae) {
+      Assertions.fail("Should throw IllegalArgumentException");
+    }
+
+    try {
+      new DataClassWithValidation("ok name");
+    } catch (final Exception iae) {
+      Assertions.fail();
+    }
+  }
+
+  @Test
+  public void testBetterSetName_invalidName() {
+    Assertions.assertThrows(IllegalArgumentException.class, () -> new DataClassWithValidation(" name starting with blank"));
+  }
+
+  @Test
+  public void testBetterSetName_validName() {
+    new DataClassWithValidation("ok name");
+  }
+}