Lab Description:
In this program we are going to use inheritance with the keyword extends to create six programs that will show the following hierarchy:

We will define the superclass and subclass and apply override method on the subclass.

Code:

package Lab_3;

class MobileDevice {
	private String deviceType = "Mobile Device";
	
	public String getDeviceType() {
		return deviceType;
	}
	public void setDeviceType(String MobileDevice) {
		this.deviceType = MobileDevice;
	}
}

package Lab_3;

class SmartPhone extends MobileDevice {
	private String deviceType = "Mobile Device -> Smart Phone"; 

	@Override
	public String getDeviceType() {
		return deviceType;
	}
	public void setDeviceType(String deviceType) {
		this.deviceType = deviceType;
	}
}

package Lab_3;

class iPhone extends SmartPhone {
	private String deviceType = "Mobile Device -> Smart Phone -> iPhone";
	
	@Override
	public String getDeviceType() {
		return deviceType;
	}
	public void setDeviceType(String deviceType) {
		this.deviceType = deviceType;
	}
}

package Lab_3;

class Android extends SmartPhone {
	private String deviceType = "Mobile Device -> Smart Phone -> Android";
	
	@Override
	public String getDeviceType() {
		return deviceType;
	}
	public void setDeviceType(String deviceType) {
		this.deviceType = deviceType;
	}
}

package Lab_3;

class WindowsPhone extends SmartPhone {
	private String deviceType = "Mobile Device -> Smart Phone -> WindowsPhone";
	
	@Override
	public String getDeviceType() {
		return deviceType;
	}
	public void setDeviceType(String deviceType) {
		this.deviceType = deviceType;
	}
}

package Lab_3;

public class MobileDeviceClient {	
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		MobileDevice myMobileDevice = new MobileDevice();
		SmartPhone mySmartPhone = new SmartPhone();
		iPhone myiPhone = new iPhone();
		Android myAndroid = new Android();
		WindowsPhone myWindowsPhone = new WindowsPhone();
		System.out.println(myMobileDevice.getDeviceType());
		System.out.println(mySmartPhone.getDeviceType());
		System.out.println(myiPhone.getDeviceType());		
		System.out.println(myAndroid.getDeviceType());
		System.out.println(myWindowsPhone.getDeviceType());
	}
}

Screenshot: