Java Abstract method declaration

/**
 * @author lautturi.com
 * Java example: Abstract method declaration in java
 */

import java.util.*;

abstract class Adapter {
	public abstract void powerSupply(); //Abstract method declaration

	public void turnOn() {
		System.out.println("turnOn the Power");
	}
}

class AC12VAdapter extends Adapter {
	public void powerSupply(){ // Implement abstract methods in Child class
		System.out.println("12V power");
	}
}

public class Lautturi {

	public static void main(String[] args) {

		AC12VAdapter obj = new AC12VAdapter();

		// access method of abstract class
		obj.turnOn();
		obj.powerSupply();

	}

}