Question

1. Create a class Pen to represent a pen according to the following requirements:

1. A pen has two attributes: id and color.
2. Add a constructer without parameters. In the initialization of the attributes, set the id to zero and the color to an empty string.
3. Add a constructer with tow parameters to initialize the attributes id and color by a specific values.
4. Add the method setId that set the id of a pen to a specific value.
5. Add the method setColor that set the color of a pen to a specific value.
6. Add the method getId that return the id of a pen.
7. Add the method getColor that return the color of a pen.

2. Create the class PenTester with the main method.

1. Create tow pen P1 and P2 using the first constructor.
2. Print the characteristics of P1 and P2.
3. Create one pen P3 using the second constructor.
4. Change the id of the pen P3.
5. Print the id of P3.

Answer 1

class Pen {
   private int id;
   private String color;

   public Pen() {
       id = 0;
       color = "";
   }

   public Pen(int aId, String aColor) {
       super();
       id = aId;
       color = aColor;
   }

   /**
   * @return the id
   */
   public int getId() {
       return id;
   }

   /**
   * @param aId
   * the id to set
   */
   public void setId(int aId) {
       id = aId;
   }

   /**
   * @return the color
   */
   public String getColor() {
       return color;
   }

   /**
   * @param aColor
   * the color to set
   */
   public void setColor(String aColor) {
       color = aColor;
   }

   /*
   * (non-Javadoc)
   *
   * @see java.lang.Object#toString()
   */
   @Override
   public String toString() {
       return "Id : " + id + ", Color : " + color;
   }

}

public class PenTester {
   public static void main(String[] args) {
       Pen P1 = new Pen();
       Pen P2 = new Pen();
       System.out.println(P1);
       System.out.println(P2);
       Pen P3 = new Pen(1, "Red");
       P3.setId(2);
       System.out.println("P3 Id : " + P3.getId());
   }
}

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