Using the class Pet from Listing 6.1, write a program to read data for five pets and display the following data: name of smallest pet, name of largest pet, name of oldest pet, name of youngest pet, average weight of the five pets, and average age of the five pets.
public class Pet {
private String name;
private int age;
private double weight;

public Pet()
{
name = "No name yet.";
age = 0;
weight = 0;
}
public Pet(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 setPet(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 Pet(String initialName)
{
name = initialName;
age = 0;
weight = 0;
}
public void setName(String newName)
{
name = newName; //age and weight are unchanged.
}

public Pet(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 Pet(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 String getName() {
return name;
}
public int getAge() {
return age;
}

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