Step by Step solution about How to resolve the algorithm Memory layout of a data structure step by step in the Java programming language

Code Overview

This code defines a class, RS232Pins9, that represents a 9-pin RS232 serial port connector and allows you to set and get the status (on or off) of individual pins. It utilizes the enums Status and Pin to model the pin status and pin configuration, respectively.

Status Enum

This simple enum represents the two possible pin status: OFF and ON.

RS232Pins9 Class

This class defines the following methods:

• getPin(int): Retrieves the status of the pin specified by its number.
• getPin(String): Retrieves the status of the pin specified by its name.
• setPin(int, Status): Sets the status of the pin specified by its number.
• setPin(String, Status): Sets the status of the pin specified by its name.
• displayPinStatus(): Prints the status of all the pins.

Pin Enum

This nested enum represents the nine pins of the RS232 connector. Each pin has a number, a name, and a status. The constructor initializes these values.

Main Method

The main method does the following:

1. Creates an instance of RS232Pins9 called plug.
2. Gets and prints the status of the "receivedData" pin.
3. Sets the status of pin 2 to ON and prints the status of the "receivedData" pin again.
4. Sets the status of the "signalGround" pin to ON.
5. Calls displayPinStatus() to print the status of all the pins.

Class Invariants

The RS232Pins9 class has the following invariants:

• Pin numbers range from 1 to 9.
• Pin names are unique.
• The status of each pin is either ON or OFF.

Runtime Behavior

The program executes as follows:

1. The main method creates an instance of RS232Pins9.
2. The getPin method is called to retrieve the status of the "receivedData" pin.
3. The setPin method is called to set the status of pin 2 to ON.
4. The getPin method is called again to check the status of the "receivedData" pin.
5. The setPin method is called to set the status of the "signalGround" pin to ON.
6. The displayPinStatus method is called to print the status of all the pins.

The output of the program is:

receivedData has status OFF
receivedData has status ON
carrierDetect has status OFF
receivedData has status ON
transmittedData has status OFF
dataTerminalReady has status OFF
signalGround has status ON
dataSetReady has status OFF
requestToSend has status OFF
clearToSend has status OFF
ringIndicator has status OFF

public final class MemoryLayoutOfDataStructure {

	public static void main(String[] aArgs) {
		RS232Pins9 plug = new RS232Pins9();
		System.out.println(plug.getPin("receivedData"));
		plug.setPin(2, Status.ON);
		System.out.println(plug.getPin("receivedData"));
		plug.setPin("signalGround", Status.ON);
		plug.displayPinStatus();
	}
	
}

enum Status { OFF, ON }
	
final class RS232Pins9 {
	
	public Status getPin(int aPinNumber) {
		for ( Pin pin : Pin.values() ) {
			if ( pin.pinNumber == aPinNumber ) {
				return pin.status;
			}
		}
		throw new IllegalArgumentException("Unknown pin number: " + aPinNumber);
	}
	
	public Status getPin(String aName) {
		for ( Pin pin : Pin.values() ) {
			if ( pin.name() == aName ) {
				return pin.status;
			}
		}
		throw new IllegalArgumentException("Unknown pin name: " + aName);
	}
	
	public void setPin(int aPinNumber, Status aStatus) {
		for ( Pin pin : Pin.values() ) {
			if ( pin.pinNumber == aPinNumber ) {
				pin.status = aStatus;
			}
		}
	}
	
	public void setPin(String aName, Status aStatus) {
		for ( Pin pin : Pin.values() ) {
			if ( pin.name() == aName ) {
				pin.status = aStatus;
			}
		}
	}
	
	public void displayPinStatus() {
		for ( Pin pin : Pin.values() ) {
			System.out.println(String.format("%-29s%s", pin.name() + " has status ", pin.status));
		}			
	}
	
	private enum Pin {
		
		carrierDetect(1, Status.OFF), receivedData(2, Status.OFF), transmittedData(3, Status.OFF),
		dataTerminalReady(4, Status.OFF), signalGround(5, Status.OFF), dataSetReady(6, Status.OFF),
		requestToSend(7, Status.OFF), clearToSend(8, Status.OFF), ringIndicator(9, Status.OFF);
		
		private Pin(int aPinNumber, Status aStatus) {
			pinNumber = aPinNumber;
			status = aStatus;
		}
		
		private int pinNumber;
		private Status status;		
		
	}

}