first issue

.classpath

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<classpath>
+	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-17">
+		<attributes>
+			<attribute name="module" value="true"/>
+		</attributes>
+	</classpathentry>
+	<classpathentry kind="src" path="src"/>
+	<classpathentry kind="output" path="bin"/>
+</classpath>

.gitignore

@@ -1,16 +1,11 @@
-# ---> Java
-# Compiled class file
+# Java
+target/
+bin/
 *.class
 
 # Log file
 *.log
 
-# BlueJ files
-*.ctxt
-
-# Mobile Tools for Java (J2ME)
-.mtj.tmp/
-
 # Package Files #
 *.jar
 *.war
@@ -20,7 +15,5 @@
 *.tar.gz
 *.rar
 
-# virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
-hs_err_pid*
-replay_pid*
-
+# do NOT ignores
+!lib/*

.project

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<projectDescription>
+	<name>exampleObserverPattern</name>
+	<comment></comment>
+	<projects>
+	</projects>
+	<buildSpec>
+		<buildCommand>
+			<name>org.eclipse.jdt.core.javabuilder</name>
+			<arguments>
+			</arguments>
+		</buildCommand>
+	</buildSpec>
+	<natures>
+		<nature>org.eclipse.jdt.core.javanature</nature>
+	</natures>
+</projectDescription>

.settings/org.eclipse.core.resources.prefs

@@ -0,0 +1,2 @@
+eclipse.preferences.version=1
+encoding/<project>=UTF-8

.settings/org.eclipse.jdt.core.prefs

@@ -0,0 +1,14 @@
+eclipse.preferences.version=1
+org.eclipse.jdt.core.compiler.codegen.inlineJsrBytecode=enabled
+org.eclipse.jdt.core.compiler.codegen.targetPlatform=17
+org.eclipse.jdt.core.compiler.codegen.unusedLocal=preserve
+org.eclipse.jdt.core.compiler.compliance=17
+org.eclipse.jdt.core.compiler.debug.lineNumber=generate
+org.eclipse.jdt.core.compiler.debug.localVariable=generate
+org.eclipse.jdt.core.compiler.debug.sourceFile=generate
+org.eclipse.jdt.core.compiler.problem.assertIdentifier=error
+org.eclipse.jdt.core.compiler.problem.enablePreviewFeatures=disabled
+org.eclipse.jdt.core.compiler.problem.enumIdentifier=error
+org.eclipse.jdt.core.compiler.problem.reportPreviewFeatures=warning
+org.eclipse.jdt.core.compiler.release=enabled
+org.eclipse.jdt.core.compiler.source=17

src/mmk/patterns/oberver/Amazon.java

@@ -0,0 +1,27 @@
+package mmk.patterns.oberver;
+
+import java.util.HashMap;
+
+public class Amazon {
+	
+	private HashMap<Observer, Product> observers = new HashMap<Observer, Product>();
+	
+	public void register(Observer observer, Product product) {
+		observers.put(observer, product);
+	}
+	
+	public void unRegister(Observer observer) {
+		observers.remove(observer);
+	}
+	
+	public void notifyAllObservers() {
+		observers.forEach((k, v) -> k.stockUpdate(v));
+	}
+	
+	public void notifyForProductName(String productName) {
+		observers.forEach((k, v) -> {
+			if(v.getName().equals(productName))
+				k.stockUpdate(v);
+		});
+	}
+}

src/mmk/patterns/oberver/App.java

@@ -0,0 +1,23 @@
+package mmk.patterns.oberver;
+
+public class App {
+
+	public static void main(String[] args) {
+		
+		var amazon = new Amazon();
+		var samsung = new Product("Samsung S23", 1000);
+		var apple = new Product("Apple 14", 2000);
+		var aliObserver = new UserObserver("Ali");
+		var zeynepObserver = new UserObserver("Zeynep");
+		
+		amazon.register(aliObserver, samsung);
+		amazon.register(zeynepObserver, apple);
+		
+		amazon.notifyForProductName("Apple 14");
+		
+		System.out.println("------------------------------");
+		
+		amazon.notifyAllObservers();
+	}
+
+}

src/mmk/patterns/oberver/Observer.java

@@ -0,0 +1,5 @@
+package mmk.patterns.oberver;
+
+public interface Observer {
+	void stockUpdate(Product product);
+}

src/mmk/patterns/oberver/Product.java

@@ -0,0 +1,27 @@
+package mmk.patterns.oberver;
+
+public class Product {
+	private String name;
+	private double price;
+	
+	public Product(String name, double price) {
+		super();
+		this.name = name;
+		this.price = price;
+	}
+	
+	public String getName() {
+		return name;
+	}
+	public void setName(String name) {
+		this.name = name;
+	}
+	public double getPrice() {
+		return price;
+	}
+	public void setPrice(double price) {
+		this.price = price;
+	}
+	
+	
+}

src/mmk/patterns/oberver/UserObserver.java

@@ -0,0 +1,22 @@
+package mmk.patterns.oberver;
+
+public class UserObserver implements Observer{
+	
+	private String fullName;
+	
+	public UserObserver(String fullName) {
+		super();
+		this.fullName = fullName;
+	}
+
+	public void stockUpdate(Product product) {
+		System.out.printf("Dear %s, Product called %s has been in stock anymore!\n", fullName, product.getName());
+	}
+	
+	public String getFullName() {
+		return fullName;
+	}
+	public void setFullName(String fullName) {
+		this.fullName = fullName;
+	}
+}