Implementing the Template Method Pattern in Java - BAEL-1289 (#2923)

* Initial Commit

* Edit pom.xml

* Changed ArtifactId

patterns/template-method/pom.xml

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<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">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>com.baeldung.templatemethodpattern</groupId>
+    <artifactId>templatemethodpattern</artifactId>
+    <version>1.0</version>
+    <packaging>jar</packaging>
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <maven.compiler.source>1.8</maven.compiler.source>
+        <maven.compiler.target>1.8</maven.compiler.target>
+    </properties>
+    <dependencies>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.12</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+</project>

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

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+package com.baeldung.templatemethodpattern.application;
+
+import com.baeldung.templatemethodpattern.model.Computer;
+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();
+        standardComputer.buildComputer();
+        standardComputer.getComputerParts().forEach((k, v) -> System.out.println("Part : " + k + " Value : " + v));
+        
+        Computer highEndComputer = new HighEndComputer();
+        highEndComputer.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

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+package com.baeldung.templatemethodpattern.model;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public abstract class Computer {
+    
+    protected Map<String, String> computerParts = new HashMap<>();
+    
+    public final void buildComputer() {
+         addMotherboard();   
+         addProcessor();
+         addMemory();
+         addHardDrive();
+         addGraphicCard();
+         addSoundCard();        
+    }
+    
+    public abstract void addProcessor();
+    
+    public abstract void addMotherboard();
+    
+    public abstract void addMemory();
+    
+    public abstract void addHardDrive();
+    
+    public abstract void addGraphicCard();
+    
+    public abstract void addSoundCard();
+    
+    public Map<String, String> getComputerParts() {
+        return computerParts;
+    }   
+}

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

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+package com.baeldung.templatemethodpattern.model;
+
+public class HighEndComputer extends Computer {
+
+    @Override
+    public void addProcessor() {
+         computerParts.put("Processor", "High End Processor");
+    }
+
+    @Override
+    public void addMotherboard() {
+         computerParts.put("Motherboard", "High End Motherboard");
+    }
+
+    @Override
+    public void addMemory() {
+         computerParts.put("Memory", "16GB");
+    }
+
+    @Override
+    public void addHardDrive() {
+         computerParts.put("Hard Drive", "2TB Hard Drive");
+    }
+
+    @Override
+    public void addGraphicCard() {
+         computerParts.put("Graphic Card", "High End Graphic Card");
+    }
+
+    @Override
+    public void addSoundCard() {
+         computerParts.put("Sound Card", "High End Sound Card");
+    }  
+}

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

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+package com.baeldung.templatemethodpattern.model;
+ 
+public class StandardComputer extends Computer {
+
+    @Override
+    public void addProcessor() {
+        computerParts.put("Processor", "Standard Processor");
+    }
+
+    @Override
+    public void addMotherboard() {
+        computerParts.put("Motherboard", "Standard Motherboard");
+    }
+
+    @Override
+    public void addMemory() {
+        computerParts.put("Memory", "8GB");
+    }
+
+    @Override
+    public void addHardDrive() {
+        computerParts.put("Hard Drive", "1TB Hard Drive");
+    }
+
+    @Override
+    public void addGraphicCard() {
+        computerParts.put("Graphic Card", "Standard Graphic Card");
+    }
+
+    @Override
+    public void addSoundCard() {
+        computerParts.put("Sound Card", "Standard Sound Card");
+    }
+}

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

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+package com.baeldung.templatemethodpatterntest;
+
+import com.baeldung.templatemethodpattern.model.HighEndComputer;
+import com.baeldung.templatemethodpattern.model.StandardComputer;
+import org.junit.Assert;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+public class TemplateMethodPatternTest {
+    
+    private static StandardComputer standardComputer;
+    private static HighEndComputer highEndComputer;
+    
+    @BeforeClass
+    public static void setUpStandardComputerInstance() {
+        standardComputer = new StandardComputer();
+    }
+    
+    @BeforeClass
+    public static void setUpHighEndComputerInstance() {
+        highEndComputer = new HighEndComputer();
+    }
+    
+    @Test
+    public void givenStandardProcessor_whenAddingProcessor_thenEqualAssertion() {
+        standardComputer.addProcessor();
+        Assert.assertEquals("Standard Processor", standardComputer
+          .getComputerParts().get("Processor"));
+    }
+    
+    @Test
+    public void givenStandardMotherBoard_whenAddingMotherBoard_thenEqualAssertion() {
+        standardComputer.addMotherboard();
+        Assert.assertEquals("Standard Motherboard", standardComputer
+          .getComputerParts().get("Motherboard"));
+    }
+    
+    @Test
+    public void givenStandardMemory_whenAddingMemory_thenEqualAssertion() {
+        standardComputer.addMemory();
+        Assert.assertEquals("8GB", standardComputer
+          .getComputerParts().get("Memory"));
+    }
+    
+    @Test
+    public void givenStandardHardDrive_whenAddingHardDrive_thenEqualAssertion() {
+        standardComputer.addHardDrive();
+        Assert.assertEquals("1TB Hard Drive", standardComputer
+          .getComputerParts().get("Hard Drive"));
+    }
+    
+    @Test
+    public void givenStandardGraphicaCard_whenAddingGraphicCard_thenEqualAssertion() {
+        standardComputer.addGraphicCard();
+        Assert.assertEquals("Standard Graphic Card", standardComputer
+          .getComputerParts().get("Graphic Card"));
+    }
+    
+    @Test
+    public void givenStandardSoundCard_whenAddingSoundCard_thenEqualAssertion() {
+        standardComputer.addSoundCard();
+        Assert.assertEquals("Standard Sound Card", standardComputer
+          .getComputerParts().get("Sound Card"));
+    }
+    
+    @Test
+    public void givenAllStandardParts_whenBuildingComputer_thenSixParts() {
+        standardComputer.buildComputer();
+        Assert.assertEquals(6, standardComputer
+          .getComputerParts().size());
+    }
+    
+    @Test
+    public void givenHightEndProcessor_whenAddingProcessor_thenEqualAssertion() {
+        highEndComputer.addProcessor();
+        Assert.assertEquals("High End Processor", highEndComputer
+          .getComputerParts().get("Processor"));
+    }
+    
+    @Test
+    public void givenHighEnddMotherBoard_whenAddingMotherBoard_thenEqualAssertion() {
+        highEndComputer.addMotherboard();
+        Assert.assertEquals("High End Motherboard", highEndComputer
+          .getComputerParts().get("Motherboard"));
+    }
+    
+    @Test
+    public void givenHighEndMemory_whenAddingMemory_thenEqualAssertion() {
+        highEndComputer.addMemory();
+        Assert.assertEquals("16GB", highEndComputer
+          .getComputerParts().get("Memory"));
+    }
+    
+    @Test
+    public void givenHighEndHardDrive_whenAddingHardDrive_thenEqualAssertion() {
+        highEndComputer.addHardDrive();
+        Assert.assertEquals("2TB Hard Drive", highEndComputer
+          .getComputerParts().get("Hard Drive"));
+    }
+    
+    @Test
+    public void givenHighEndGraphicCard_whenAddingGraphicCard_thenEqualAssertion() {
+        highEndComputer.addGraphicCard();
+        Assert.assertEquals("High End Graphic Card", highEndComputer
+          .getComputerParts().get("Graphic Card"));
+    }
+    
+    @Test
+    public void givenHighEndSoundCard_whenAddingSoundCard_thenEqualAssertion() {
+        highEndComputer.addSoundCard();
+        Assert.assertEquals("High End Sound Card", highEndComputer
+          .getComputerParts().get("Sound Card"));
+    }
+    
+    @Test
+    public void givenAllHighEndParts_whenBuildingComputer_thenSixParts() {
+        highEndComputer.buildComputer();
+        Assert.assertEquals(6, highEndComputer.getComputerParts().size());
+    }  
+}