This lab will introduce you to how Java programs work with numbers and expressions.
As you should know from your reading, numbers in Java come in six different categories which differ in range and precision. But just in can you can't remember the details, here's a little table to help you out.
Type  What it Holds 

byte  Holds a whole number from 128 to 127. 
short  Holds a whole number from 32,768 to 32,767. 
int  Holds a whole number from 2,147,483,648 to 2,147,483,647. 
long  Holds an whole integer from 9,223,372,036,854,775,808 to 9,223,372,036,854,775,807. 
float  Holds a decimal number with a range of about 10^{38} to 10^{38} and a precision of about seven decimal digits. 
double  Holds a decimal number with a range of about 10^{308} to 10^{308} and a precision of about fifteen decimal digits. 
In the table below, you see four range testers written as a Java applet. The four buttons for these applets can be used to modify the displayed numbers. For example, when you press the * 10 button, the number is multiplied by 10. The number is stored in six different ways. Originally all six numbers are the same, but with additions and multiplications the numbers will start to differ.
Below each tester is a short little exercise we'd like you to try out. Read the description with each exericse to increase your understanding of the limitations of computer arithmetic.
Try to set this number to 1000. Notice that the byte
has already execeeded its maximum capacity. It is now displaying
a negative number very different from 1000.

Try to set this one to 1000000050. Notice that the byte
and short have been long exhausted. However, there's
something interesting about the float . Although a
float can hold a number as large as 10^{38},
it can only hold seven significant decimal places. So, it
can't distinguish between 1000000000 and 1000000050.

Try to set this one to 1000000000000000050, 10^{18} + 50.
This number is near the top of the range for a long .
Notice that the double can't hold this precise value.

Patiently go up 10^{40}. Everything but the double
is in trouble. The float even holds a special value
corresponding to positive infinity.

Show the instructor your numbers.
Programmers need to understand a bit about how different data types are stored in the computer. Here we are going to look at how integers are stored in the computer. We've written a Java applet to give you a little practice in converting decimal numbers to their binary representations.
In the table below, you'll see some decimal numbers in the left hand side. These are your targets. In the middle of the table, you see a row of black and red dots. These represent bits or binary numbers. Red means binary 1. Black means binary 0. Go ahead and mash one of the dots. It changes state  0 becomes 1, 1 becomes 0. Notice that the rightmost number also changes. It is the decimal number corresponding to the binary number.
Your job is to set the binary bits so that the right column matches the left column, if possible. This can be a little tricky for negative numbers as they are encoded in twos complement notation as required by the Java virtual machine specification. In this case, first find the positive number number that is one less than the absolute value of the negative number and then reverse all the bits. For example, if the goal is to find 127, first find 126 and then reverse all the bits.
Start off with eight bit numbers. These correspond to the
Java byte
type.
Target  Your guess 

20  
43  
66  
99  
127  
128 
Now try out binary representations using 16 bits.
These correspond to Java short
integers.
Target  Your guess 

128  
201  
201  
32767  
32768  
1 
Ask your lab instructor to verify that you've pushed all the right buttons.
Begin by using the following link to download a ZIP file called Expr.zip. Then extract the directory Expr into your csci/201 directory.
Next start up NetBeans and open the project you now have stored in your csci/201/Expr directory.
If you do not remember how to do this, you may go back to the introductory NetBeans lab. Your lab insructor may be willing to help you with the extraction this week, but by next week this activity needs to be on autopilot.
Java executes expressions according to the order of operations you learned in high school algebra. We hope you know this by heart, but if you've forgotten, just remember that expressions inside of parenthesis are evaluated first, and that the operators multiplication, division and remainder are evaluated before the operators addition and subtraction.
An expression contains operators that must be evaluated.
Usually expressions appear in assignment statements of the form:
Variable = Expression
In such statements, the expression is
evaluated and the result of the evaluation is then
assigned to the variable. This process is illustrated in the
following Stack N' Heap simulation:
Study, build, and run the Expr
class.
Presently, this program uses a random number generator
(edu.unca.cs.LabAids.TestValues
)
to generate four numbers, two integers i
and j
and two doubleprecision floating point numbers
y
and z
,
and then displays the result of evaluating
expression 1 in the table below.
Your job is to modify the main
method to print
all of the
ten expressions listed in the table below.
Notice that the first expression is already done for you. You can use the Java applet on the right to check out your solutions.
Expression Number 
Expression  

1  Average of y and z 

2  Average of i and j
as a decimal number 

3  The remainder when i is
divided by j 

4  y^{2} +
4 j z 

5  (y^{2}  z^{3}) 

6  (y + z)
/ (y  z) 

7  i / (i + 1) 

8  i / (i + 1.0) 

9  (i / j) * j 

10  i^{y}
Hint: Use the pow method of the Math class. 
After you have thoroughly tested your code, and you understand why the expressions print as they do, ask your instructor to test your code.