Implemeting the template method pattern in Java - BAEL-1289 (#3012)

* Initial Commit

* Delete domain classes

patterns/template-method/src/main/java/com/baeldung/templatemethodpattern/application/Application.java

@@ -1,18 +1,21 @@
 package com.baeldung.templatemethodpattern.application;
 
 import com.baeldung.templatemethodpattern.model.Computer;
+import com.baeldung.templatemethodpattern.model.ComputerBuilder;
+import com.baeldung.templatemethodpattern.model.HighEndComputerBuilder;
+import com.baeldung.templatemethodpattern.model.StandardComputerBuilder;
 import com.baeldung.templatemethodpattern.model.HighEndComputer;
 import com.baeldung.templatemethodpattern.model.StandardComputer;
 
 public class Application {
     
     public static void main(String[] args) {
-        Computer standardComputer = new StandardComputer();
+        ComputerBuilder standardComputerBuilder = new StandardComputerBuilder();
-        standardComputer.buildComputer();
+        Computer standardComputer = standardComputerBuilder.buildComputer();
         standardComputer.getComputerParts().forEach((k, v) -> System.out.println("Part : " + k + " Value : " + v));
         
-        Computer highEndComputer = new HighEndComputer();
+        ComputerBuilder highEndComputerBuilder = new HighEndComputerBuilder();
-        highEndComputer.buildComputer();
+        Computer highEndComputer = highEndComputerBuilder.buildComputer();
         highEndComputer.getComputerParts().forEach((k, v) -> System.out.println("Part : " + k + " Value : " + v));
     }
 }

patterns/template-method/src/main/java/com/baeldung/templatemethodpattern/model/Computer.java

@@ -1,20 +1,20 @@
 package com.baeldung.templatemethodpattern.model;
 
-import java.util.ArrayList;
-import java.util.HashMap;
-import java.util.List;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.ArrayList;
+import java.util.List;
 
-public abstract class Computer {
+public abstract class ComputerBuilder {
     
     protected Map<String, String> computerParts = new HashMap<>();
     protected List<String> moterboardSetupStatus = new ArrayList<>();
     
-    public final void buildComputer() {
+    public final Computer buildComputer() {
         addMotherboard();
         setupMotherboard();
         addProcessor();
+        return getComputer();
     }
     
     public abstract void addMotherboard();
@@ -30,4 +30,8 @@ public abstract class Computer {
     public Map<String, String> getComputerParts() {
         return computerParts;
     }
+     
+    private Computer getComputer() {
+        return new Computer(computerParts);
+    }
 }

patterns/template-method/src/main/java/com/baeldung/templatemethodpattern/model/ComputerBuilder.java

@@ -0,0 +1,37 @@
+package com.baeldung.templatemethodpattern.model;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+public abstract class ComputerBuilder {
+
+    protected Map<String, String> computerParts = new HashMap<>();
+    protected List<String> moterboardSetupStatus = new ArrayList<>();
+    
+    public final Computer buildComputer() {
+        addMotherboard();
+        setupMotherboard();
+        addProcessor();
+        return getComputer();
+    }
+    
+    public abstract void addMotherboard();
+
+    public abstract void setupMotherboard();
+
+    public abstract void addProcessor();
+
+    public List<String> getMotherboardSetupStatus() {
+        return moterboardSetupStatus;
+    }
+
+    public Map<String, String> getComputerParts() {
+        return computerParts;
+    }
+    
+    private Computer getComputer() {
+        return new Computer(computerParts);
+    }
+}

patterns/template-method/src/main/java/com/baeldung/templatemethodpattern/model/HighEndComputerBuilder.java

@@ -0,0 +1,21 @@
+package com.baeldung.templatemethodpattern.model;
+
+public class HighEndComputerBuilder extends ComputerBuilder {
+
+    @Override
+    public void addMotherboard() {
+        computerParts.put("Motherboard", "High-end Motherboard");
+    }
+    
+    @Override
+    public void setupMotherboard() {
+        moterboardSetupStatus.add("Screwing the high-end motherboard to the case.");
+        moterboardSetupStatus.add("Pluging in the power supply connectors.");
+        moterboardSetupStatus.forEach(step -> System.out.println(step));
+    }
+    
+    @Override
+    public void addProcessor() {
+         computerParts.put("Processor", "High-end Processor");
+    }
+}

patterns/template-method/src/main/java/com/baeldung/templatemethodpattern/model/StandardComputerBuilder.java

@@ -0,0 +1,21 @@
+package com.baeldung.templatemethodpattern.model;
+ 
+public class StandardComputerBuilder extends ComputerBuilder {
+
+    @Override
+    public void addMotherboard() {
+        computerParts.put("Motherboard", "Standard Motherboard");
+    }
+    
+    @Override
+    public void setupMotherboard() {
+        moterboardSetupStatus.add("Screwing the standard motherboard to the case.");
+        moterboardSetupStatus.add("Pluging in the power supply connectors.");
+        moterboardSetupStatus.forEach(step -> System.out.println(step));
+    }
+    
+    @Override
+    public void addProcessor() {
+        computerParts.put("Processor", "Standard Processor");
+    }
+}

patterns/template-method/src/test/java/com/baeldung/templatemethodpatterntest/TemplateMethodPatternTest.java

@@ -1,25 +1,30 @@
 package com.baeldung.templatemethodpatterntest;
 
+import com.baeldung.templatemethodpattern.model.Computer;
+import com.baeldung.templatemethodpattern.model.HighEndComputerBuilder;
+import com.baeldung.templatemethodpattern.model.StandardComputerBuilder;
 import com.baeldung.templatemethodpattern.model.HighEndComputer;
 import com.baeldung.templatemethodpattern.model.StandardComputer;
 import org.junit.Assert;
 import static org.junit.Assert.assertEquals;
 import org.junit.BeforeClass;
 import org.junit.Test;
+import static org.hamcrest.CoreMatchers.instanceOf;
+import static org.junit.Assert.assertThat;
 
 public class TemplateMethodPatternTest {
 
-    private static StandardComputer standardComputer;
+    private static StandardComputerBuilder standardComputerBuilder;
-    private static HighEndComputer highEndComputer;
+    private static HighEndComputerBuilder highEndComputerBuilder;
 
     @BeforeClass
-    public static void setUpStandardComputerInstance() {
+    public static void setUpStandardComputerBuilderInstance() {
-        standardComputer = new StandardComputer();
+        standardComputerBuilder = new StandardComputerBuilder();
     }
 
     @BeforeClass
-    public static void setUpHighEndComputerInstance() {
+    public static void setUpHighEndComputerBuilderInstance() {
-        highEndComputer = new HighEndComputer();
+        highEndComputerBuilder = new HighEndComputerBuilder();
     }
 
     @Test
@@ -30,45 +35,55 @@ public class TemplateMethodPatternTest {
 
     @Test
     public void givenStandardMotheroboard_whenSetup_thenTwoEqualAssertions() {
-        standardComputer.setupMotherboard();
+        standardComputerBuilder.setupMotherboard();
-        assertEquals("Screwing the standard motherboard to the case.", standardComputer.getMotherboardSetupStatus().get(0));
+        assertEquals("Screwing the standard motherboard to the case.", standardComputerBuilder.getMotherboardSetupStatus().get(0));
-        assertEquals("Plugin in the power supply connectors.",  standardComputer.getMotherboardSetupStatus().get(1));
+        assertEquals("Pluging in the power supply connectors.", standardComputerBuilder.getMotherboardSetupStatus().get(1));
     }
 
     @Test
     public void givenStandardProcessor_whenAddingProcessor_thenEqualAssertion() {
-        standardComputer.addProcessor();
+        standardComputerBuilder.addProcessor();
-        assertEquals("Standard Processor", standardComputer.getComputerParts().get("Processor"));
+        assertEquals("Standard Processor", standardComputerBuilder.getComputerParts().get("Processor"));
     }
 
     @Test
     public void givenAllStandardParts_whenBuildingComputer_thenTwoParts() {
-        standardComputer.buildComputer();
+        standardComputerBuilder.buildComputer();
-        assertEquals(2, standardComputer.getComputerParts().size());
+        assertEquals(2, standardComputerBuilder.getComputerParts().size());
+    }
+    
+    @Test
+    public void givenAllStandardParts_whenComputerisBuilt_thenComputerInstance() {
+        assertThat(standardComputerBuilder.buildComputer(), instanceOf(Computer.class));
     }
     
     @Test
     public void givenHighEnddMotherBoard_whenAddingMotherBoard_thenEqualAssertion() {
-        highEndComputer.addMotherboard();
+        highEndComputerBuilder.addMotherboard();
-        Assert.assertEquals("High-end Motherboard", highEndComputer.getComputerParts().get("Motherboard"));
+        Assert.assertEquals("High-end Motherboard", highEndComputerBuilder.getComputerParts().get("Motherboard"));
     }
 
     @Test
     public void givenHighEnddMotheroboard_whenSetup_thenTwoEqualAssertions() {
-        highEndComputer.setupMotherboard();
+        highEndComputerBuilder.setupMotherboard();
-        assertEquals("Screwing the high-end motherboard to the case.", highEndComputer.getMotherboardSetupStatus().get(0));
+        assertEquals("Screwing the high-end motherboard to the case.", highEndComputerBuilder.getMotherboardSetupStatus().get(0));
-        assertEquals("Plugin in the power supply connectors.", highEndComputer.getMotherboardSetupStatus().get(1));
+        assertEquals("Pluging in the power supply connectors.", highEndComputerBuilder.getMotherboardSetupStatus().get(1));
     }
 
     @Test
     public void givenHightEndProcessor_whenAddingProcessor_thenEqualAssertion() {
-        highEndComputer.addProcessor();
+        highEndComputerBuilder.addProcessor();
-        Assert.assertEquals("High-end Processor", highEndComputer.getComputerParts().get("Processor"));
+        assertEquals("High-end Processor", highEndComputerBuilder.getComputerParts().get("Processor"));
     }
     
     @Test
     public void givenAllHighEnddParts_whenBuildingComputer_thenTwoParts() {
-        highEndComputer.buildComputer();
+        highEndComputerBuilder.buildComputer();
-        assertEquals(2, highEndComputer.getComputerParts().size());
+        assertEquals(2, highEndComputerBuilder.getComputerParts().size());
+    }
+    
+    @Test
+    public void givenAllHighEndParts_whenComputerisBuilt_thenComputerInstance() {
+        assertThat(standardComputerBuilder.buildComputer(), instanceOf(Computer.class));
     }
 }