Question

(JAVA) Use the Pet.java program from the original problem (down below) Compile it.

Create a text file named pets10.txt with 10 pets (or use the one below). Store this file in the same folder as your “class” file(s). The format is the same format used in the original homework problem. Each line in the file should contain a pet name (String), a comma, a pet’s age (int) in years, another comma, and a pet’s weight (double) in pounds.

Perform the following operations in the sequence given below:

1. Create a driver program in a separate source file which contains main
2. Open the “txt” file
3. Declare and create an array of 10 Pet elements
4. Read each line in the file, instantiate a Pet object, and assign to the next unused element in the array of Pet
5. Close the “txt” file
6. Print a report showing the name, weight, and age of all of the pets in the array:
   1. Do not use the toString method in Pet.
   2. Instead, format the report using nicely-aligned columns,
      • The pet names should all be left-aligned
      • The weights and ages of the pets should all be right-aligned.
      • The weights should be displayed to 1 decimal point to the right
7. Determine and print the name, weight, and age of the heaviest pet and the oldest pet. Use your toStringmethod to print this information.
8. Determine and print the name of the pet with the longest name (use toString)

Do not determine or print any of the information requested in steps 6, 7, or 8 as you are reading in the data. These must be determined and printed only after all pets have been read from the file and placed into the array.

Please don’t make any changes to the Pet class. You may create as many methods in your driver class as you wish.

When completed, submit a copy of:

• Your driver program (must be separate from the Pet class)
• Your “txt” file
• The output from your program as a PrintScreen

You might consider this…

Use the following code to open your data file:

< above / outside of main, declare the following constant >

private static final String FILE_NAME = "pets10.txt" ;

< inside main >

FileInputStream inputStream = null;

try

{

input stream = new FileInputStream(FILE_NAME);

}

catch (FileNotFoundException e)

{

System.out.println("Can't find " + FILE_NAME + ", aborting. ");

System.exit(0);

}

Scanner petScanner = new Scanner(inputStream);

// Setup scanner and attach to the data file

When done reading the file, close the named input stream using:

  try
  {
     inputStream.close() ;  
  }
  catch (IOException e)
  {
  }

Loop through the text file using the following pseudocode:

declare and create an array of 10 Pets, but do NOT create Pet objects yet
loop through the ten pets in the pets10.txt file
create a new Pet object and assign to the next available element of the array
change delimiter of the scanner to a comma
read the name and age of the pet from the scanner and store in the Pet object
change delimiter to a comma / white space
read the weight of the pet and store in the object

public class Pet
{
// Instance variables
private String name;
private int age; //in years
private double weight; //in pounds

// Default values for instance variables
private static final String DEFAULT_NAME = "No name yet." ;
private static final int DEFAULT_AGE = -1 ;
private static final double DEFAULT_WEIGHT = -1.0 ;

/***************************************************
* Constructors to create objects of type Pet
***************************************************/

// no-argument constructor
public Pet( )
{
this(DEFAULT_NAME, DEFAULT_AGE, DEFAULT_WEIGHT) ;
}
// only name provided
public Pet(String initialName)
{
this(initialName, DEFAULT_AGE, DEFAULT_WEIGHT) ;
}
// only age provided
public Pet(int initialAge)
{
this(DEFAULT_NAME, initialAge, DEFAULT_WEIGHT) ;
}
// only weight provided
public Pet(double initialWeight)
{
this(DEFAULT_NAME, DEFAULT_AGE, initialWeight) ;
}
// full constructor (all three instance variables provided)
public Pet(String initialName, int initialAge, double initialWeight)
{
setName(initialName) ;
setAge(initialAge) ;
setWeight(initialWeight) ;
}

/****************************************************************
* Mutators and setters to update the Pet. Setters for age and
* weight validate reasonable weights are specified
****************************************************************/

// Mutator that sets all instance variables
public void set(String newName, int newAge, double newWeight)
{
setName(newName) ;
setAge(newAge) ;
setWeight(newWeight) ;
}

// Setters for each instance variable (validate age and weight)
public void setName(String newName)
{
name = newName;
}
public void setAge(int newAge)
{
if ((newAge < 0) && (newAge != DEFAULT_AGE))
{
System.out.println("Error: Invalid age.");
System.exit(99);
}
age = newAge;
}
public void setWeight(double newWeight)
{
if ((newWeight < 0.0) && (newWeight != DEFAULT_WEIGHT))
{
System.out.println("Error: Invalid weight.");
System.exit(98);
}
weight = newWeight;
}

/************************************
* getters for name, age, and weight
************************************/
public String getName( )
{
return name;
}
public int getAge( )
{
return age;
}
public double getWeight( )
{
return weight;
}

/****************************************************
* toString() shows the pet's name, age, and weight
* equals() compares all three instance variables
****************************************************/
public String toString( )
{
return ("Name: " + name + " Age: " + age + " years"
+ " Weight: " + weight + " pounds");
}
public boolean equals(Pet anotherPet)
{
if (anotherPet == null)
{
return false ;
}
return ((this.getName().equals(anotherPet.getName())) &&
(this.getAge() == anotherPet.getAge()) &&
(this.getWeight() == anotherPet.getWeight())) ;
}
}

Answer 1

// Pet.java

public class Pet {
  
   // Instance variables
   private String name;
   private int age; //in years
   private double weight; //in pounds

   // Default values for instance variables
   private static final String DEFAULT_NAME = "No name yet." ;
   private static final int DEFAULT_AGE = -1 ;
   private static final double DEFAULT_WEIGHT = -1.0 ;

   /***************************************************
   * Constructors to create objects of type Pet
   ***************************************************/

   // no-argument constructor
   public Pet( )
   {
   this(DEFAULT_NAME, DEFAULT_AGE, DEFAULT_WEIGHT) ;
   }
  
   // only name provided
   public Pet(String initialName)
   {
   this(initialName, DEFAULT_AGE, DEFAULT_WEIGHT) ;
   }
   // only age provided
   public Pet(int initialAge)
   {
   this(DEFAULT_NAME, initialAge, DEFAULT_WEIGHT) ;
   }
   // only weight provided
   public Pet(double initialWeight)
   {
   this(DEFAULT_NAME, DEFAULT_AGE, initialWeight) ;
   }
   // full constructor (all three instance variables provided)
   public Pet(String initialName, int initialAge, double initialWeight)
   {
   setName(initialName) ;
   setAge(initialAge) ;
   setWeight(initialWeight) ;
   }
  
   /****************************************************************
   * Mutators and setters to update the Pet. Setters for age and
   * weight validate reasonable weights are specified
   ****************************************************************/

   // Mutator that sets all instance variables
   public void set(String newName, int newAge, double newWeight)
   {
   setName(newName) ;
   setAge(newAge) ;
   setWeight(newWeight) ;
   }

   // Setters for each instance variable (validate age and weight)
   public void setName(String newName)
   {
   name = newName;
   }
   public void setAge(int newAge)
   {
   if ((newAge < 0) && (newAge != DEFAULT_AGE))
   {
   System.out.println("Error: Invalid age.");
   System.exit(99);
   }
   age = newAge;
   }
  
   public void setWeight(double newWeight)
   {
   if ((newWeight < 0.0) && (newWeight != DEFAULT_WEIGHT))
   {
   System.out.println("Error: Invalid weight.");
   System.exit(98);
   }
   weight = newWeight;
   }

   /************************************
   * getters for name, age, and weight
   ************************************/
   public String getName( )
   {
   return name;
   }
   public int getAge( )
   {
   return age;
   }
   public double getWeight( )
   {
   return weight;
   }
  
   /****************************************************
   * toString() shows the pet's name, age, and weight
   * equals() compares all three instance variables
   ****************************************************/
   public String toString( )
   {
   return ("Name: " + name + " Age: " + age + " years"
   + " Weight: " + weight + " pounds");
   }
  
   public boolean equals(Pet anotherPet)
   {
   if (anotherPet == null)
   {
   return false ;
   }
   return ((this.getName().equals(anotherPet.getName())) &&
   (this.getAge() == anotherPet.getAge()) &&
   (this.getWeight() == anotherPet.getWeight())) ;
   }

}
//end of Pet.java

// PetApplication.java
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.Scanner;

public class PetApplication {
  
   private static final String FILE_NAME = "pets10.txt" ;
  
   public static void main(String[] args) {

       Pet pets[] = new Pet[10];
       String name;
       int age;
       double weight;
      
       FileInputStream inputStream = null;
       try
       {

           inputStream = new FileInputStream(FILE_NAME);

       }
       catch (FileNotFoundException e)
       {
           System.out.println("Can't find " + FILE_NAME + ", aborting. ");
           System.exit(0);
       }
      
       // Setup scanner and attach to the data file
       Scanner petScanner = new Scanner(inputStream);
       petScanner.useDelimiter(",|\\R"); // set the delimiter as comma and end of line
       int i = 0;

// read till end of file or till 10 pets have been read
       while((petScanner.hasNext()) && (i < pets.length))
       {  
           name = petScanner.next();
           System.out.println(name);
           age = petScanner.nextInt();
           System.out.println(age);
           weight = petScanner.nextDouble();
           System.out.println(weight);
           pets[i] = new Pet(name, age, weight);
           i++;
       }
      
       try { inputStream.close() ; } catch (IOException e) { }
       petScanner.close();
      
       System.out.printf("\n%-20s%10s%10s","Name","Age","Weight");
       // loop over the pets array to display the pet information in a formatted manner
       for(i=0;i<pets.length;i++)
       {
           System.out.printf("\n%-20s%10d%10.1f",pets[i].getName(),pets[i].getAge(),pets[i].getWeight());
       }
      
       System.out.println("\n\nHeaviest Pet: "+pets[getHeaviestPet(pets)]);
       System.out.println("Oldest Pet: "+pets[getOldestPet(pets)]);
       System.out.println("Longest name Pet: "+pets[getLongestName(pets)]);
   }
  
   // method to return the index of the heaviest pet
   public static int getHeaviestPet(Pet pets[])
   {
       int maxIdx = 0;
       // loop over pets array and determine the index of heaviest pet
       for(int i=0;i<pets.length;i++)
       {
           if(pets[i].getWeight() > pets[maxIdx].getWeight())
               maxIdx = i;
       }
      
       return maxIdx;
   }
  
   // method to return the index of the oldest pet
   public static int getOldestPet(Pet pets[])
   {
       int maxIdx = 0;
       // loop over pets array and determine the index of oldest pet
       for(int i=0;i<pets.length;i++)
       {
           if(pets[i].getAge() > pets[maxIdx].getAge())
               maxIdx = i;
       }
      
       return maxIdx;
   }
  
   // method to return the index of the pet with the longest name
   public static int getLongestName(Pet pets[])
   {
       int maxIdx = 0;
       // loop over pets array and determine the index of longest name pet
       for(int i=0;i<pets.length;i++)
       {
           if(pets[i].getName().length() > pets[maxIdx].getName().length())
               maxIdx = i;
       }
      
       return maxIdx;
   }

}
//end of PetApplication.java

Output:

Input file:

1 Toby,5,23.67 Tweety, 7,30 3 Hugo, 10,65 4 Hero, 4,35.66 5 Kitty,9,55 6 Tiger, 12,77.50 7 Boss, 8,58.75 8 Tommy, 9,85.89 Bugs, 5,50 10 Paige, 11,75

Output:

Name Toby Tweety Hugo Hero Kitty Tiger Boss Tommy Bugs Paige Weight 23.7 30.0 65.0 35.7 55.0 77.5 58.8 85.9 50.0 75.0 Heaviest Pet: Name: Tommy Age: 9 years Weight: 85.89 pounds Oldest Pet: Name: Tiger Age: 12 years Weight: 77.5 pounds Longest name Pet: Name: Tweety Age: 7 years Weight: 30.0 pounds