generics and design patterns

Author: oefremidis

java-path-core-despattern/pom.xml

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+<?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">
+	<parent>
+		<artifactId>java-path-core</artifactId>
+		<groupId>gr.codelearn</groupId>
+		<version>2021.1.0</version>
+	</parent>
+	<modelVersion>4.0.0</modelVersion>
+
+	<artifactId>java-path-core-despattern</artifactId>
+
+	<properties>
+		<maven.compiler.source>17</maven.compiler.source>
+		<maven.compiler.target>17</maven.compiler.target>
+	</properties>
+
+</project>

java-path-core-despattern/src/main/java/gr/codelearn/designpatterns/behavioral/AESEncryptionStrategy.java

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+package gr.codelearn.designpatterns.behavioral;
+
+public class AESEncryptionStrategy implements EncryptionStrategy {
+	@Override
+	public String encryptData(String text) {
+		return text.hashCode() + " " + "AES".hashCode()  ;
+	}
+}

java-path-core-despattern/src/main/java/gr/codelearn/designpatterns/behavioral/EncryptionStrategy.java

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+package gr.codelearn.designpatterns.behavioral;
+
+public interface EncryptionStrategy {
+	String encryptData(String text);
+}

java-path-core-despattern/src/main/java/gr/codelearn/designpatterns/behavioral/Encryptor.java

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+package gr.codelearn.designpatterns.behavioral;
+
+public class Encryptor {
+	private EncryptionStrategy strategy;
+
+	public void setStrategy(EncryptionStrategy strategy){
+		this.strategy = strategy;
+	}
+
+	public String encrypt(String plainText){
+		return strategy.encryptData(plainText);
+	}
+}

java-path-core-despattern/src/main/java/gr/codelearn/designpatterns/behavioral/Main.java

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+package gr.codelearn.designpatterns.behavioral;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class Main {
+	private static final Logger logger = LoggerFactory.getLogger(Main.class);
+
+	public static void main(String[] args) {
+		Encryptor encryptor = new Encryptor();
+
+		EncryptionStrategy aesStrategy = new AESEncryptionStrategy();
+		EncryptionStrategy rsaStrategy = new RSAEncryptionStrategy();
+
+		encryptor.setStrategy(aesStrategy);
+		logger.info("{}", encryptor.encrypt("This is a text"));
+
+		encryptor.setStrategy(rsaStrategy);
+		logger.info("{}", encryptor.encrypt("This is a text"));
+	}
+}

java-path-core-despattern/src/main/java/gr/codelearn/designpatterns/behavioral/RSAEncryptionStrategy.java

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+package gr.codelearn.designpatterns.behavioral;
+
+public class RSAEncryptionStrategy implements EncryptionStrategy {
+	@Override
+	public String encryptData(String text) {
+		return text.hashCode() + " " + "RSA".hashCode()  ;
+	}
+}

java-path-core-despattern/src/main/java/gr/codelearn/designpatterns/creational/EagerSingleton.java

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+package gr.codelearn.designpatterns.creational;
+
+public class EagerSingleton {
+	private static final EagerSingleton INSTANCE = new EagerSingleton();
+
+	private EagerSingleton(){}
+
+	public static EagerSingleton getInstance(){
+		return INSTANCE;
+	}
+}

java-path-core-despattern/src/main/java/gr/codelearn/designpatterns/creational/LazySingleton.java

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+package gr.codelearn.designpatterns.creational;
+
+public class LazySingleton {
+
+	private static LazySingleton instance = null;
+
+	private LazySingleton(){}
+
+	public synchronized static LazySingleton getInstance(){
+		if (instance == null){
+			instance = new LazySingleton();
+		}
+		return instance;
+	}
+}

java-path-core-despattern/src/main/java/gr/codelearn/designpatterns/creational/Main.java

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+package gr.codelearn.designpatterns.creational;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class Main {
+	private static final Logger logger = LoggerFactory.getLogger(Main.class);
+
+	public static void main(String[] args) {
+		ScoreTracker scoreTracker = ScoreTracker.getInstance();
+
+		logger.info("{}", scoreTracker.getScore());
+		scoreTracker.increaseScore(10);
+		logger.info("{}", scoreTracker.getScore());
+
+		scoreTracker = ScoreTracker.getInstance();
+		logger.info("{}", scoreTracker.getScore());
+	}
+}

java-path-core-despattern/src/main/java/gr/codelearn/designpatterns/creational/ScoreTracker.java

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+package gr.codelearn.designpatterns.creational;
+
+public class ScoreTracker {
+	private static ScoreTracker instance = null;
+	private int score = 0;
+
+	private ScoreTracker(){}
+
+	public static ScoreTracker getInstance(){
+		if (instance == null){
+			instance = new ScoreTracker();
+		}
+		return instance;
+	}
+
+	public void increaseScore(int number){
+		score += number;
+	}
+
+	public int getScore(){
+		return score;
+	}
+
+
+}