java lambda 08.25.18

java lambda 08.25.18

Author: hmkcode

java-lambda/README.md

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+Using Lambda to Implement Funtional Interface Method
+====================================================
+
+- We have a *virtual* `Button` that when clicked will call an abstract method **onClick()** of a listener interface `OnClickListener`.
+- We need to implement the **onClick()** so that it prints the `Button` name. 
+
+
+`OnClickListener.java`
+
+```java
+package com.hmkcode;
+
+public interface OnClickListener {
+	void onClick(Button button);
+}
+```
+
+`Button.java`
+
+```java
+package com.hmkcode;
+
+public class Button {
+
+	private OnClickListener onClickListener;
+	private String name;
+
+	// click the button
+	public void click(){
+		this.onClickListener.onClick(this);
+	}
+	
+	// getters & setters
+}
+```
+

java-lambda/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">
+  <modelVersion>4.0.0</modelVersion>
+
+  <groupId>com.hmkcode</groupId>
+  <artifactId>java-lambda</artifactId>
+  <version>1.0-SNAPSHOT</version>
+
+  <name>java-lambda</name>
+
+ <build>
+    <plugins>
+        <plugin>
+        <artifactId>maven-compiler-plugin</artifactId>
+        <version>3.8.0</version>
+        <configuration>
+                <source>1.8</source>
+                <target>1.8</target>
+        </configuration>
+     </plugin>
+        <plugin>
+        <groupId>org.codehaus.mojo</groupId>
+        <artifactId>exec-maven-plugin</artifactId>
+        <version>1.6.0</version>        
+        <configuration>
+             <mainClass>com.hmkcode.App</mainClass>
+        </configuration>
+        </plugin>
+    </plugins>
+  </build>
+  
+</project>

java-lambda/src/main/java/com/hmkcode/App.java

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+package com.hmkcode;
+
+
+public class App implements OnClickListener
+{
+    public static void main( String[] args ){
+        System.out.println( "Running App..." );
+        new App().run(); 
+    }
+
+    public void run(){
+        
+        Button myButton = new Button();
+        myButton.setName("MyButton");
+        
+        // 1. implements onClickListener
+        //myButton.setOnClickListener(this);
+        
+        // 2. anonymous class
+        /*myButton.setOnClickListener(new OnClickListener() {
+			@Override
+			public void onClick(Button button) {
+				System.out.println(button.getName() +" Clicked! - anonymous class");
+			}
+		}); */
+        
+        // 3. lambda
+    	OnClickListener lambda = button -> { System.out.println(button.getName()+" Clicked! - lambda"); } ;
+    	myButton.setOnClickListener(lambda);
+	
+    	
+        // click the button
+    	myButton.click();
+    }
+    
+    
+	@Override
+	public void onClick(Button button) {
+		System.out.println(button.getName() +" Clicked! - implements interface");
+		
+	}
+}

java-lambda/src/main/java/com/hmkcode/Button.java

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+package com.hmkcode;
+
+public class Button {
+
+	private OnClickListener onClickListener;
+	private String name;
+
+	public void click(){
+		this.onClickListener.onClick(this);
+	}
+	
+	
+	public String getName() {
+		return name;
+	}
+
+	public void setName(String name) {
+		this.name = name;
+	}
+
+	public OnClickListener getOnClickListener() {
+		return onClickListener;
+	}
+
+	public void setOnClickListener(OnClickListener onClickListener) {
+		this.onClickListener = onClickListener;
+	}
+	
+	
+	
+}

java-lambda/src/main/java/com/hmkcode/OnClickListener.java

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+package com.hmkcode;
+
+
+public interface OnClickListener {
+	void onClick(Button button);
+	
+}