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Thread: Implementing a Driver to following code

  1. #1
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    Default Implementing a Driver to following code

    So here are my code segements:

    1. The Interface with problem Im trying to solve

     
    // Design a Java interface Lockable that includes the following methods: setKey,
    // lock, unlock, and locked. The setKey, lock, and unlock methods take an 
    // integer parameter that represents the key. The setKey method establishes
    // the key. The lock and unlock methods lock and unlock the object,
    // but only if the key passed in is correct. The locked method returns a
    // boolean indicating whether or not the object is locked. A Lockable object
    // represents an object whose regular methods are protected: if the object is
    // locked, the method cannot be invoked; if it is unlocked, they can be invoked.
    // Redesign and implement a version of this Coin class so that it is Lockable.
     
    public interface Lockable
    {
      boolean locked();
      void setKey(int password);
      boolean lock(int password);
      boolean unlock(int password);
     
      }

    2. The class coin with modifications:

     
     
    public class Coin implements Lockable 
    {
      private int key; // password to make it lockable
      private boolean locked; // if true, object is locked
      private final int HEADS = 0;
      private final int TAILS = 1;
      private int face;
     
      public boolean locked() 
      {
        return this.locked;
      }
     
      public void setKey(int password) 
      {
        this.key = password;
        this.locked = true;
     
      }
     
      public boolean lock(int password) 
      {
        if (password == this.key) 
        {
          this.locked = true;
          return true;
        } 
        else 
        {
          return false;
        }
      }
     
      public boolean unlock(int password) 
      {
        if (password == this.key) 
        {
          this.locked = false;
          return true;
        } 
        else 
        {
          return false;
        }
      }
     
      public Coin()
      {
        locked = true;
      }
     
      public boolean flip() 
      {
        if (this.locked == false) 
        {
          face = (int) (Math.random() * 2);
          return true;
        }
        return false;
      }
     
     
      public boolean isHeads() 
      {
        return (face == HEADS);
      }
     
      public String toString() 
      {
        if (this.locked == false) 
        {
     
          String faceName;
     
          if (face == HEADS)
            faceName = "Heads";
          else
            faceName = "Tails";
     
          return faceName;
        } 
        else
          return "";
      }
    }

    3. Since the questions asked for only the methods, i believe thats as far he wants us to go but he made a driver to test if it worked, something similar to this

     
    public class Driver
    {
      public static void main(String[] args) 
      {
     
        Coin myCoin = new Coin();
        boolean bSuccess, bResult;
     
        myCoin.setKey(1234);
        bSuccess = myCoin.flip(); // Should Fail, coin is locked
        bResult = myCoin.unlock(12345);
        if (bResult) // coin is unlocked
        {
          myCoin.flip();
          boolean iValue = myCoin.isHeads();
        }
        else
        {
          System.out.println("You better remember the LOCK value");
        }
     
     
     
      }
     
    }

    Some errors I get when running this:
    1. After prompting for the password it does nothing
    2. Even i tried to tidy the code, some variables were left behind since the program for this situation.

    If someone could help me fix my Driver class and allowing Coin to implement it

    Thanks everyone in Advance!


  2. #2
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    Default Re: Implementing a Driver to following code

    Hi,

    i have check the code its working fine.

    1) Very first thing your code is not asking any password.
    2) your give code is compiling and running without error.

    What extactly you expect as result and as input?
    Hardik Jadhav

  3. #3
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    Default Re: Implementing a Driver to following code

    bResult = myCoin.unlock(12345);
    Your key is set to 1234 and you are passing 12345 so it will return false.
    So the output must be;
    You better remember the LOCK value

  4. #4
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    Default Re: Implementing a Driver to following code

    The output I want for this program to do is when i run it, it will ask for a password, if its wrong, it will prompt "You better remember the Lock value" if its the correct password, it wil run the program

    What must I add to my code in order for it to work?

    Thanks!

  5. #5
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    Default Re: Implementing a Driver to following code

    You must add;
    1. Take values from the user.
    2. Pass his value to the function which will perform your desired functions.

    Good Luck.

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