CSC 211 -- ANSWERS FOR PRACTICE FINAL B

1. a. An instance variable is declared outside of any 
      method in the class and is global for the class.
      A local variable is declared inside a method and
      can only be used inside that method.

   b. Space for the array must be initialized with a
      statement such as
      a = new int[10];

   c. public static void main(String[] args)
      {
          int i;
          for(i = 0; i <= args[0].length(); i++)
              System.out.println(args[0].charAt(i));
      }

2.  Let w, d, l, o, and g be abbreviations for the
    strings in the a array.  Then we have
 a[0] a[1] a[2] a[3] a[4] temp  i  a[i].charAt(i)
+----+----+----+----+----+----+---+--------------+
  w    d    l    o    g    d    1
  d    w    l    o    g    l    2
  d    l    w    o    g    o    3
  d    l    o    w    g    g    4
  d    l    o    g    w    g    5

  i     a[i]    a[i].charAt(i)      Output:
+---+----------+--------------+     deapr
  0  date             d
  1  lemon            e
  2  orange           a
  3  grapefruit       p
  4  watermelon       r


3.     a[0]   a[1]   a[2]
     +------+------+------+
     |  o   |  o   |  o   |
     +--|---+--|---+--|---+   
        |       \    /
        |        \  /
        |         \/
        |         /\
        |        /  \
        |       /    \
        |      /      \
        |     /        \
        |    |          |
        V    V          V
    +---+---------+  +---+-----------+  Output:
    | a |    b    |  | a |     b     |  20 ssfoxuuuu
    +---+---------+  +---+-----------+  24 ttgoose2
    | 10|ssfox    |  | 22|ttgoose    |  20 ssfoxuuuu
    | 15|ssfoxuu  |  | 24|ttgoose2   |
    | 20|ssfoxuuuu|  +---+-----------+
    +---+---------+


4a. public class GroceryItem
    {
        private String name;
        private int barCode;
        private double price;

        public GroceryItem(String aName, int aBarCode, 
            double aPrice)
        {
            name = aName;
            barCode = aBarCode;
            price = aPrice;
        }

        public String toString()
        {
            return name + " " + barCode + " " + price;
        }

        public double getPrice()
        {
            return price;
        }

        public void setPrice(double newPrice)
        {
            price = newPrice;
        }
    }

4b. public class Main
    {
        public static void main(String[] args)
        {
            FileReader fr = new FileReader(
                "c:\\GroceryInfo.txt");
            BufferedReader br = new BufferedReader(fr);
            GroceryItem x = new GroceryItem(
                br.readLine(),
                Integer.parseInt(br.readLine()),
                Double.parseDouble(br.readLine()));
            System.out.println(x);
            System.out.println(x.getPrice());
            x.setPrice(2.95);
            System.out.println(x);
            System.out.println(x.getPrice());
        }
    }


5.  public static void main(String[] args)
    {
        int[] a = new double[100];
        int i, max = 0.0;
        for(i = 0; i <= 99; i++)
            a[i] = Math.random();
        for(i = 0; i <= 99; i++)
            if (a[i] > max)
                max = a[i];
        System.out.println(
            "Largest random number is " + max);
    }


6.  public class Main
    {
        public static void main(String[] args)
        {
            StringChecker x = new StringChecker();
        }
    }

    public class StringChecker extends JFrame
    {
        JTextField t;
        JButton b;
        ClickDetector c;

        public StringChecker()
        {
            super("StringChecker");
            t = new JTextField(15);
            b = new JButton("Submit");
            p = new JPanel();
            c = new ClickDetector();
            p.add(t);
            p.add(b);
            b.addActionListener(c);
            setContentPane(p);
            setSize(100, 100);
            show();
        }

        private class ClickDetector implements ActionListener
        {
            public void actionPerformed(ActionEvent e)
            {
                String word;
                word = t.getText();
                if (word.length() >= 2 && (word.charAt(0) == 'a' ||
                    pword.charAt(1) == 'a'))
                       t.setText("yes");
                else
                       t.setText("no");
            }
        }
    }