• Quiz Today
• Read Chapter 3

• Primitive types int and double
• What is a double?
• Need something similar to TextField

public class IntField extends TextField
{
    public IntField();
    public IntField(int size);
    public void setInt(int number);
    public int getInt();
}
public class DoubleField extends TextField
{
    public DoubleField();
    public DoubleField(int size);
    public void setDouble(double num);
    public Double getDouble();
}

• need a precise notation
• more formal method

1. <identifier> -> //a sequence of letters and/or digits that begin with a letter//
   where // indicates italics in textbook
   read: an object called an 'identifier' can be ...

could have used:
1. <identifier> -> a sequence of letters and/or digits that begin with a letter
   but will use // notation.
   
   Example:
   <identifier> -> msg42
   <identifier> -> PigLatin

2. <expression> -> <str expression>

3. <expression> -> <int expression>

4. <str expression> -> <identifier>

5. <str expression> -> "//any string of printable chars//"

6. <str expression> -> <str expression> + <str expression>

7. <int expression> -> //any sequence of digits//

8. <int expression> -> <identifier>

9. <int expression> -> <int expression> <int op> <int expression>

10. <int op> -> + | - | * | / | %

11. <statement> -> <identifier> = <expression>;

12. <compound statement>	->	{
    		//a sequence of <statements>s
    		each followed by a semicolon//
    		}