Public class LightController help please

[zafreen iqbal]

If some one can point me in the right direction for this code for my assignment I would really appreciate it. I have tried my best but I'm getting no where.

im confused on the public void grow(int size) method. at first i thou of doing a while loop, but im not getting anywhere tbh. i think its the fact that i dont know what size is. i think im confused. if someone could just start me off with the method or explain to me what the question is trying to say regarding the argument size as after this method i have a couple more which are similar that i ned to do too.

>Now complete the public instance method `grow(int size)` that causes the circle referenced by the instance variable light to expand.
The argument, `size`, is an int that represents the new diameter of the `Circle` object referenced by the instance variable `light`. You can assume that `size` will always be an even number that is bigger than the current diameter (50) of the `Circle` object. In order to get the correct effect, you should use a loop within which the circle referenced by light expands its diameter in steps of 2 and its `xPos` and `yPos` decrease in steps of 1, until diameter reaches the value of size. At each step the object referenced by light should randomly change its colour.

    import ou.*;
    import java.util.*;

    /**
 
    * Class LightController
 
    * This class uses the Circle class, and the Shapes window 
 
    * to simulate a disco light, that grows and shrinks and 
 
    * changes colour. 
 
    * @author M250 Module Team
 
    * @version 1.0
 
    */

    public class LightController

    {
   
    /* instance variables */
   
    private Circle light;   // simulates a circular disco light in the Shapes window
   
    private Random randomNumberGenerator;
   
    /**
    
    * Default constructor for objects of class LightController.
   
    */
  
    public LightController()
    {
      super();
      this.randomNumberGenerator = new Random(); 
      light = new Circle();
      light.setColour(OUColour.GREEN);
      light.setDiameter(50);
      light.setXPos(122);
      light.setYPos(162);
     }

     /**
     * Returns a randomly generated int between 0 (inclusive) 
     * and number (exclusive). For example if number is 6,
     * the method will return one of 0, 1, 2, 3, 4, or 5.
     */
     public int getRandomInt(int number)
     {
      return this.randomNumberGenerator.nextInt(number);
     }
   
    /**
     * Returns the instance variable, light.
     */
     public Circle getLight()
     {
       return this.light;
    }
   
     /** 
     * Randomly sets the colour of the instance variable 
     * light to red, green, or purple.
     */  
     public void changeColour()
     {
        this.getRandomInt(3);
        int l = getRandomInt(3);
        if (l == 0)
        {
           this.light.setColour(OUColour.RED);
        }
        else if (l == 1)
        {
           this.light.setColour(OUColour.GREEN);
        }
        else if (l == 2)
        {
            this.light.setColour(OUColour.PURPLE);
        }
        }
         
   
   
       /** 
     * Grows the diameter of the circle referenced by the 
     * receiver's instance variable light, to the argument size.  
     * The diameter is incremented in steps of 2,
     * the xPos and yPos are decremented in steps of 1 until the
     * diameter reaches the value given by size. 
     * Between each step there is a random colour change.  The message 
    * delay(anInt) is used to slow down the graphical interface, as required.
     */   
    public void grow(int size)
    { 
      
       }
     }
    
      /** 
     * Shrinks the diameter of the circle referenced by the 
     * receiver's instance variable light, to the argument size.  
     * The diameter is decremented in steps of 2,
     * the xPos and yPos are incremented in steps of 1 until the
     * diameter reaches the value given by size. 
     * Between each step there is a random colour change.  The message 
     * delay(anInt) is used to slow down the graphical interface, as required.
     */     
     public void shrink(int size)
     {   
        // Add your code for Q2 part (d) here
    }
 
    /** 
     * Expands the diameter of the light by the amount given by
     * sizeIncrease (changing colour as it grows).
     * 
     * The method then contracts the light until it reaches its
     * original size (changing colour as it shrinks).
     */     
    public void lightCycle(int sizeIncrease)
    {
       // Add your code for Q2 part (e) here
    }
      
    /** 
     * Prompts the user for number of growing and shrinking
     * cycles. Then prompts the user for the number of units
     * by which to increase the diameter of light.
     * Method then performs the requested growing and 
     * shrinking cycles.
     */     
    public void runLight()
    {  
     // Add your code for Q2 part (f) here
    }  

    /**
     * Causes execution to pause by time number of milliseconds.
     */
    private void delay(int time)
    {
       try
       {
          Thread.sleep(time); 
       }
       catch (Exception e)
       {
          System.out.println(e);
        } 
      }  

[Carey Brown]

zafreen iqbal wrote:If some one can point me in the right direction for this code for my assignment I would really appreciate it. I have tried my best but I'm getting no where.

im confused on the public void grow(int size) method. at first i thou of doing a while loop, but im not getting anywhere tbh. i think its the fact that i dont know what size is. i think im confused. if someone could just start me off with the method or explain to me what the question is trying to say regarding the argument size as after this method i have a couple more which are similar that i ned to do too.

>Now complete the public instance method `grow(int size)` that causes the circle referenced by the instance variable light to expand.
The argument, `size`, is an int that represents the new diameter of the `Circle` object referenced by the instance variable `light`. You can assume that `size` will always be an even number that is bigger than the current diameter (50) of the `Circle` object. In order to get the correct effect, you should use a loop within which the circle referenced by light expands its diameter in steps of 2 and its `xPos` and `yPos` decrease in steps of 1, until diameter reaches the value of size. At each step the object referenced by light should randomly change its colour.

You have a circle that starts out with some known diameter. Size will be the diameter when the looping is complete. You will loop in increments of 2 for the diameter and -1 for x and y pos. You will add a delay after each increment. So, you do know what size is. I would suggest writing down the steps in English (or your native language) first before writing any code.

[Campbell Ritchie]

If you are planning to use that in a Swing application do not use Thread.sleep. You would have to find some other way to create the delay, possibly with a Timer object. Beware: there are two Timer classes.

[Campbell Ritchie]

No, there are three Timer classes.

[Campbell Ritchie]

And welcome to the Ranch

[Matt Matthews]

 public LightController()
   {
      super();
      this.randomNumberGenerator = new Random(); 
      this.light = new Circle (50 , OUColour.GREEN);
      this.xPos = 122;
      this.yPos = 162;
            
   }

I am not sure what the OUColour is suppose to be? I assume OU is from a class library?
I put the 'this' keyword into the code since you would have declared these (int xPos, int yPos) as instance variables.

[zafreen iqbal]

Thank you for all your help, i missed out the class Circle which is also very important. sorry about that.

In the Class LightController i have only 2 instance variables.
n yes OU is from the class library.

im doing a for loop for this, but dont knw if it will work.
eg;
for (int diameter = 50; diameter < size; diameter++)
etc.
i dont know if im going the right way though

import ou.*;
/**
 * The class Circle defines a shape with the characteristics of a circle.
 *
 * @author M250 Module Team
 * @version 2.0
 */

public class Circle extends OUAnimatedObject
{
   /* Instance variables */
   private OUColour colour;
   private int xPos;
   private int yPos;
   private int diameter;

   /**
    * Zero argument constructor for objects of class Circle 
    * that sets colour to OUColour.BLUE, 
    * xPos and yPos to 0,.and diameter to 30. 
    */
   public Circle()
   {
      super();
      this.colour = OUColour.BLUE;
      this.xPos = 0;
      this.yPos = 0;
      this.diameter = 30;
   }

   /**
    * Constructor for objects of class Circle with arguments for
    * diameter and colour, and which sets xPos and yPos to 0.
    */
   public Circle(int aDiameter, OUColour aColour)
   {
      super();
      this.diameter = aDiameter;
      this.colour = aColour;
      this.xPos = 0;
      this.yPos = 0;
   }

   /* Instance methods */    

   /**
    * Sets the diameter of the receiver to the value of the argument aDiameter.
    */
   public void setDiameter(int aDiameter)
   {
      this.diameter = aDiameter;
      this.update();
   }

   /**
    * Returns the diameter of the receiver.
    */
   public int getDiameter()
   {
      return this.diameter;
   }

   /**
    * Sets the colour of the receiver to the value of the argument aColour.
    */
   public void setColour (OUColour aColour)
   {
      this.colour = aColour;
      this.update();
   }

   /**
    * Returns the colour of the receiver.
    */
   public OUColour getColour ()
   {
      return this.colour;
   }

   /**
    * Sets the horizontal position of the receiver to the value of the argument x.
    */
   public void setXPos(int x)
   {
      this.xPos = x;
      this.update();
   }

   /**
    * Returns the horizontal position of the receiver.
    */
   public int getXPos()
   {
      return this.xPos;
   }

   /**
    * Sets the vertical position of the receiver to the value of the argument y.
    */
   public void setYPos(int y)
   {
      this.yPos = y;
      this.update();
   }

   /**
    * Returns the vertical position of the receiver.
    */
   public int getYPos()
   {
      return this.yPos;
   }

   /**
    * Returns a string representation of the receiver.
    */
   public String toString()
   {
      return "An instance of class " + this.getClass().getName() 
      + ": position (" + this.getXPos() + ", " + this.getYPos() 
      + "), diameter " + this.getDiameter() + ", colour " + this.getColour();
   }
}

[Matt Matthews]

  /* instance variables */  
     
    private Circle light;   // simulates a circular disco light in the Shapes window  
     
    private Random randomNumberGenerator;  
     
    /** 
     
    * Default constructor for objects of class LightController. 
    
    */  
    
    public LightController()  
    {  
      super();  
      this.randomNumberGenerator = new Random();   
      light = new Circle();  
      light.setColour(OUColour.GREEN);  
      light.setDiameter(50);  
      light.setXPos(122);  
      light.setYPos(162);  
     } 

You say you only have two instance variables for the LightController class but in your constructor you are calling xPos,yPos etc. Won't that give you compilation errors since those instance variables don't actually exist in your class?

[Campbell Ritchie]

Don't use aDiameter for the name of the parameter; it is poor style and awkward to read.

/**
 * blahblahblah
 * @param diameter blahblahblah
 */
public void setDiameter(int diameter)
{
   this.diameter = diameter;
}

You are already using this. so there is no risk of confusing the parameter with the field. I would suggest this enhancement to prevent anybody trying to pass a negative size:-

/**
 * blahblahblah
 * @param diameter blahblahblah must be non-negative
 * @throws IllegalArgumentException if diameter is negative
 */
public void setDiameter(int diameter)
{
   if (diameter < 0)
   {
      throw new IllegalArgumentException("Negative diameter not permitted");
   }
   this.diameter = diameter;
}

The header for the loop looks all right, but you realise it will never run if size is not greater than 50. Whether it works or not depends on the contents of the loop, which you haven't shown us. Thread.sleep() will not work at all well if you are using Swing.

Don't double‑space the code and be careful about spellings; both things can make the post harder to read especially for people who didn't grow up speaking or reading English.

[zafreen iqbal]

Thank you, and sorry about the English.

[Campbell Ritchie]

You're welcome and apologies accepted