Programming revision

%% revision part 1
public class ResistorCodes {

	public static void main(String[] args) {
		ResistorCodes p1 = new ResistorCodes();

		System.out.println(p1.ResistorValue("red","red","orange") + " ohms");
		System.out.println(p1.ResistorValue("violet","green","yellow") + " ohms");
		System.out.println(p1.ResistorValue("black","brown","brown") + " ohms");


	}



	private int ResistorValue(String col1, String col2, String col3) {

		int total = 0;
		total = (int) ((getVal(col1)*10 + getVal(col2))*Math.pow(10, getVal(col3)));
		return total;


	}

	private int getVal(String colour) {
		if (colour == "black")
			return 0;
		else if (colour == "brown")
			return 1;
		else if (colour == "red")
			return 2;
		else if (colour == "orange")
			return 3;
		else if (colour == "yellow")
			return 4;
		else if (colour == "green")
			return 5;
		else if (colour == "blue")
			return 6;
		else if (colour == "violet")
			return 7;
		else if (colour == "grey")
			return 8;
		else if (colour == "white")
			return 9;
		else
		return 0;

	}

}



%% revision part 2
public class Chess {

	public static void main(String[] args) {
		Chess c1 = new Castle(1,2);
		System.out.println(c1);
		Chess c2 = new Knight(3,4);
		System.out.println(c2);

	}

}

class Castle extends Chess {

	private int x;
	private int y;

	@Override
	public String toString() {
		return "Castle at position: " + x + "," + y;
	}

	public Castle(int i, int j) {
		this.x = i;
		this.y = j;
	}

}

class Knight extends Chess {
	private int x;
	private int y;

	@Override
	public String toString() {
		return "Knight at position: " + x + "," + y;
	}

	public Knight(int i, int j) {
		this.x = i;
		this.y = j;
	}

}

%% revision part 3
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.util.Scanner;

public class stringToInt {

	public static void main(String[] args) throws FileNotFoundException {
		stringToInt st1 = new stringToInt();
		st1.runDemo();


	}

	private void runDemo() throws FileNotFoundException {
		int result = 0;
		Scanner sc = new Scanner(new FileInputStream("file.txt"));
		while (sc.hasNextLine()){
			String val1 = sc.nextLine();
			String val2 = sc.nextLine();
			String op = sc.nextLine();
			char oper = op.charAt(0);

			if(oper == '+'){
				result = Integer.parseInt(val1) + Integer.parseInt(val2);
				System.out.println(result);
			}

			else if(oper == '-'){
				result = Integer.parseInt(val1) - Integer.parseInt(val2);
				System.out.println(result);
			}

			else if(oper == '*'){
				result = Integer.parseInt(val1) * Integer.parseInt(val2);
				System.out.println(result);
			}

			else if(oper == '/'){
				result = Integer.parseInt(val1) / Integer.parseInt(val2);
				System.out.println(result);
			}

		}
		sc.close();


	}

}


%%revision part 4

import java.text.DecimalFormat;

public class Change {

	public static void main(String[] args) {
		Change cg = new Change();
		cg.changeBack(350);
		cg.changeBack(510);
		cg.changeBack(125);

	}



	private void changeBack(double cost) {
		try{
			if (cost > 500)
				throw new NotEnoughMoneyException();
			else if (cost <= 500){
				double money = 5.00;
				double decimalCost = cost / 100.0;
				double change = money - decimalCost;
				DecimalFormat dm = new DecimalFormat("0.00");

				System.out.println("You bought an item for $" + dm.format(decimalCost));
				System.out.println("Your change is $" + dm.format(change) + ":");

				int count = 0;
				if (change >= 2){
					count = (int) (change/2);
					change = change - 2*count;
				}
				System.out.println(count + " two dollar coins");


				count = 0;
				if (change >= 1){
					count = (int) (change/1);
					change = change - 1*count;
				}
				System.out.println(count + " one dollar coins");



				count = 0;
				if (change >= 0.5){
					count = (int) (change/0.5);
					change = change - 0.5*count;
				}
				System.out.println(count + " fifty cent coins");



				count = 0;
				if (change >= 0.2){
					count = (int) (change/0.2);
					change = change - 0.2*count;
				}
				System.out.println(count + " twenty cent coins");



				count = 0;
				if (change >= 0.1){
					count = (int) (change/0.1);
					change = change - 0.1*count;
				}
				System.out.println(count + " ten cent coins");



				change = Double.parseDouble(dm.format(change));

				count = 0;
				if (change >= 0.05){
					count = (int) (change/0.05);
					change = change - 0.05*count;
				}
				System.out.println(count + " five cent coins");

				System.out.println();
			}
		}
		catch (NotEnoughMoneyException e){
			System.out.println(e.getMessage());

		}

	}

}

class NotEnoughMoneyException extends Exception {

	/**
	 *
	 */
	private static final long serialVersionUID = 4257723934124110055L;


	public NotEnoughMoneyException()
	{
		super("You Do Not Have Enough Money!\n");
	}
	public NotEnoughMoneyException(String message)
	{
		super(message);
	}


}