- We have a virtual
Buttonthat when clicked will call an abstract method onClick() of a listener interfaceOnClickListener. - We need to implement the onClick() so that it prints the
Buttonname.
OnClickListener.java
package com.hmkcode;
public interface OnClickListener {
void onClick(Button button);
}Button.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
}- We have three ways to achieve that:
- Implement
OnClickListenerand override onClick() method. - Use
OnClickListeneras an anonymous class. - Use Lambda.
- Our main class is
App.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();
}
}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");
}
}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();
}
}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