Question

1. Write a new class, Cat, derived from PetRecord – Add an additional attribute to store the number of lives remaining: numLives – Write a constructor that initializes numLives to 9 and initializes name, age, & weight based on formal parameter values

2. Write a main method to test your Cat constructor & call the inherited writeOutput() method

3. Write a new writeOutput method in Cat that uses “super” to print the Cat’s name, age, weight & numLives – Does this method overload or override PetRecord.writeOutput()? (include the answer to this question as a comment in your code)

4. Instantiate 2 Cat objects with identical arguments to the constructor and compare them using .equals – In your code, add a comment as to what happens

5. Add the following equals method (next slide) to your Cat class. Complete the method to return true if the calling cat object and the parameter object have the same name and age, and false otherwise.

Cat equals method // TO DO: Does this equals method override or overload the Object equals method? Refer to the Java docs to see the signature of the Object equals method: https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html. Add a comment in your code with the answer. public boolean equals(Object otherObj) { if (otherObj == this) return true; if (!(otherObj instanceof Cat)) { return false; } Cat otherCat = (Cat) otherObj; // TO DO: Add comparison code that returns true if the cats // have the same name and age, false otherwise // (note that you can do this in one long line of code).

/***************************************************
* Class for basic pet records: name, age, and weight.
***************************************************/
public class PetRecord
{
// member variables are protected for direct access in inherited classes
protected String name;
protected int age;//in years
protected double weight;//in pounds

public void writeOutput()
{
System.out.println("Name: " + name);
System.out.println("Age: " + age + " years");
System.out.println("Weight: " + weight + " pounds");
}

public PetRecord(String initialName, int initialAge,
double initialWeight)
{
name = initialName;
if ((initialAge < 0) || (initialWeight < 0))
{
System.out.println("Error: Negative age or weight.");
System.exit(0);
}
else
{
age = initialAge;
weight = initialWeight;
}
}

public void set(String newName, int newAge, double newWeight)
{
name = newName;
if ((newAge < 0) || (newWeight < 0))
{
System.out.println("Error: Negative age or weight.");
System.exit(0);
}
else
{
age = newAge;
weight = newWeight;
}
}

public PetRecord(String initialName)
{
name = initialName;
age = 0;
weight = 0;
}

public void set(String newName)
{
name = newName; //age and weight are unchanged.
}

public PetRecord(int initialAge)
{
name = "No name yet.";
weight = 0;
if (initialAge < 0)
{
System.out.println("Error: Negative age.");
System.exit(0);
}
else
age = initialAge;
}

public void set(int newAge)
{
if (newAge < 0)
{
System.out.println("Error: Negative age.");
System.exit(0);
}
else
age = newAge;
//name and weight are unchanged.
}

public PetRecord(double initialWeight)
{
name = "No name yet";
age = 0;
if (initialWeight < 0)
{
System.out.println("Error: Negative weight.");
System.exit(0);
}
else
weight = initialWeight;
}

public void set(double newWeight)
{
if (newWeight < 0)
{
System.out.println("Error: Negative weight.");
System.exit(0);
}
else
weight = newWeight; //name and age are unchanged.
}

public PetRecord()
{
name = "No name yet.";
age = 0;
weight = 0;
}

public String getName()
{
return name;
}

public int getAge()
{
return age;
}

public double getWeight()
{
return weight;
}
}

Answer 1

class PetRecord

{

// member variables are protected for direct access in inherited classes

protected String name;

protected int age;//in years

protected double weight;//in pounds

public void writeOutput()

{

System.out.println("Name: " + name);

System.out.println("Age: " + age + " years");

System.out.println("Weight: " + weight + " pounds");

}

public PetRecord(String initialName, int initialAge,

double initialWeight)

{

name = initialName;

if ((initialAge < 0) || (initialWeight < 0))

{

System.out.println("Error: Negative age or weight.");

System.exit(0);

}

else

{

age = initialAge;

weight = initialWeight;

}

}

public void set(String newName, int newAge, double newWeight)

{

name = newName;

if ((newAge < 0) || (newWeight < 0))

{

System.out.println("Error: Negative age or weight.");

System.exit(0);

}

else

{

age = newAge;

weight = newWeight;

}

}

public PetRecord(String initialName)

{

name = initialName;

age = 0;

weight = 0;

}

public void setName(String newName)

{

name = newName; //age and weight are unchanged.

}

public PetRecord(int initialAge)

{

name = "No name yet.";

weight = 0;

if (initialAge < 0)

{

System.out.println("Error: Negative age.");

System.exit(0);

}

else

age = initialAge;

}

public void setAge(int newAge)

{

if (newAge < 0)

{

System.out.println("Error: Negative age.");

System.exit(0);

}

else

age = newAge;

//name and weight are unchanged.

}

public PetRecord(double initialWeight)

{

name = "No name yet";

age = 0;

if (initialWeight < 0)

{

System.out.println("Error: Negative weight.");

System.exit(0);

}

else

weight = initialWeight;

}

public void setWeight(double newWeight)

{

if (newWeight < 0)

{

System.out.println("Error: Negative weight.");

System.exit(0);

}

else

weight = newWeight; //name and age are unchanged.

}

public PetRecord()

{

name = "No name yet.";

age = 0;

weight = 0;

}

public String getName()

{

return name;

}

public int getAge()

{

return age;

}

public double getWeight()

{

return weight;

}

}

class Cat extends PetRecord

{

private int numLives;

public Cat(String initialName, int initialAge,double initialWeight)

{

super(initialName,initialAge,initialWeight);

numLives = 9;

}

public void writeOutput() // override base class writeOutput() method

{

super.writeOutput(); // call to base class writeOutput() method

System.out.println("Number of Lives : "+numLives);

}

public boolean equals(Object otherObj)

{

if (otherObj == this)

return true;

if (!(otherObj instanceof Cat))

{ return false; }

Cat otherCat = (Cat) otherObj;

// TO DO: Add comparison code that returns true if the cats

// have the same name and age, false otherwise

// (note that you can do this in one long line of code).

if(this.name == otherCat.name && this.age == otherCat.age )

return true;

else

return false;

}

}

public class Test

{

public static void main (String[] args)

{

Cat c = new Cat("Pussy",2,4.8);

c.writeOutput();

Cat c1 = new Cat("Pussy",2,5.9);

if(c.equals(c1))

System.out.println("Both cats are identical");

else

System.out.println("Cats are different");

}

}

Output:

Name: Pussy
Age: 2 years
Weight: 4.8 pounds
Number of Lives : 9
Both cats are identical

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