/**
 Class for basic pet records: name, age, and weight.
*/
public class Pet
{
    private String name;
    private int age; //in years
    private double weight; //in pounds
    
    /**
     This main is just a demonstration program.
    */
    public static void main(String[] args)
    {
        Pet myDog = new Pet( );
        myDog.set("Fido", 2, 5.5);
        myDog.writeOutput( );
        System.out.println("Changing name.");
        myDog.set("Rex");
        myDog.writeOutput( );
        System.out.println("Changing weight.");
        myDog.set(6.5);
        myDog.writeOutput( );
        System.out.println("Changing age.");
        myDog.set(3);
        myDog.writeOutput( );
    }
    
    public void writeOutput( )
    {
        System.out.println("Name: " + name);
        System.out.println("Age: " + age + " years");
        System.out.println("Weight: " + weight + " pounds");
    }
    
    public void set(String newName)
    {
        name = newName;
        //age and weight are unchanged.
    }
    
    public void set(int newAge)
    {
        if (newAge <= 0)
        {
            System.out.println("Error: invalid age.");
            System.exit(0);
        }
        else
            age = newAge;
        //name and weight are unchanged. 
    }
    
    public void set(double newWeight)
    {
        if (newWeight <= 0)
        {
            System.out.println("Error: invalid weight.");
            System.exit(0);
        }
        else
            weight = newWeight;
        //name and age are unchanged. 
    }
    
    public void set(String newName, int newAge, double newWeight)
    {
        name = newName;
        if ((newAge <= 0) || (newWeight <= 0))
        {
            System.out.println("Error: invalid age or weight.");
            System.exit(0);
        }
        else
        {
            age = newAge;
            weight = newWeight;
        }
    }
    
    public String getName( )
    {
        return name;
    }

    public int getAge( )
    {
        return age;
    }
    
    public double getWeight( )
    {
        return weight;
    }
}