1. Explain the difference between an object and a class.

2. If a and b are declared as
   String a, b;
   explain the difference between a == b and a.equals(b);.

3. Write a main program that accepts an arbitrary number of command line arguments that represent integers. Print the sum of these integers.

public static void main(String[] args)
{
    String[] a = {"grapefruit", "orange", "lemon",
         "date", "watermelon"};
    String temp, k;
    int i, j, m;
    int[] c = {2, 1, 2, 3, 1, 3, 4, 4};
    int[] d = {0, 0, 4, 0, 4, 1, 2, 1};
    temp = a[4];
    a[4] = a[2];
    a[2] = temp;
    for(i = 0; i <= 7; i++)
    {
       j = c[i];
       k = a[j];
       m = d[i];
       System.out.print(k.charAt(m));
    }
}

public class A
{
    int a;
    String b;

    public A(int intVal, String strVal)
    {
       a = intVal + 10;
       b = "xxx" + strVal;
    }

    public A(String strVal, int intVal)
    {
       a = intVal + 20;
       b = "yyy" + strVal;
    }

    public void update()
    {
       a += 5;
       b += "zzz";
    }

    public void update(int intVal)
    {
       a += intVal;
       b += String.valueOf(intVal);
    }

    public String toString()
    {
       return a + " " + b;
    }

}

public class Main
{
    public static void main(String[] args)
    {
       int i;
       A[] x = new A[3];
       x[0] = new A(5, "dog");
       x[1] = new A("cat", 7);
       x[2] = x[0];
       x[0].update();
       x[1].update(2);
       x[2].update();
       for(i = 0; i <= 2; i++)
          System.out.println(x[i]);
    }
}

1. Write code for a Student class. The private instance variables are name, id, totalHours, and totalGradePoints. Write code for a parameterized constructor that initalizes the instance variables, a toString method, and a getGpa method that returns the student's GPA, equal to totalGradePoints divided by totalHours.

2. Write a main method that creates one Student object using data read from the text file c:\StudentInfo.txt. You may assume one item of data per line, for example:
   Rogers, William
   3453426576
   85
   326