update README.md

update README.md

Author: hmkcode

java-lambda/README.md

@@ -4,7 +4,6 @@ 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
@@ -34,3 +33,119 @@ public class Button {
 }
 ```
 
+- We have three ways to achieve that:
+ 1. **Implement** `OnClickListener` and override **onClick()** method.
+ 2. Use `OnClickListener` as an anonymous class.
+ 3. Use Lambda.
+ 
+- Our main class is `App.java`
+
+```java
+package com.hmkcode;
+
+public class App
+{
+    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
+        
+        // 2. anonymous class
+
+        // 3. lambda
+    	
+	
+    	// click the button
+    	myButton.click();
+    }
+}
+```
+
+### 1. **Implement** `OnClickListener` and override **onClick()** method
+
+```java
+public class App implements OnClickListener
+{
+    public static void main( String[] args ){...}
+
+    public void run(){
+        
+        Button myButton = new Button();
+        myButton.setName("MyButton");
+        
+        // 1. implements onClickListener
+        myButton.setOnClickListener(this);
+        
+        // click the button
+    	myButton.click();
+    }
+	
+	@Override
+	public void onClick(Button button) {
+		System.out.println(button.getName() +" Clicked! - implements interface");
+		
+	}
+}
+```
+
+### 2. Use `OnClickListener` as an anonymous class
+
+```java
+public class App
+{
+    public static void main( String[] args ){...}
+
+    public void run(){
+        
+        Button myButton = new Button();
+        myButton.setName("MyButton");
+                
+        // 2. anonymous class
+        myButton.setOnClickListener(new OnClickListener() {
+			@Override
+			public void onClick(Button button) {
+				System.out.println(button.getName() +" Clicked! - anonymous class");
+			}
+		}); 
+        
+        // click the button
+    	myButton.click();
+    }
+}
+```
+
+### 3. Use Lambda
+
+```java
+public class App
+{
+    public static void main( String[] args ){...}
+
+    public void run(){
+        
+        Button myButton = new Button();
+        myButton.setName("MyButton");
+
+        // 3. lambda
+    	OnClickListener lambda = button -> { System.out.println(button.getName()+" Clicked! - lambda"); } ;
+    	myButton.setOnClickListener(lambda);
+		
+        // click the button
+    	myButton.click();
+    } 
+}
+```
+
+*To run the code use*
+
+```
+java-lambda>mvn exec:java
+```
+