Recitation R2 - Java Expressions, Strings, and Scanners
The goals of this lab are as follows:
Learn about Java variables and expressions
Understand integer versus floating point math
See how the order of precedence affects expressions
Learn about calling methods on a String object
Learn how to use a Scanner object to read input
Find out the difference between println, print, and printf.
Learn how to format output using printf.
Getting Started
Create a new Java Project named R2, and make a class named R2.
Java Expressions
Your TA will help you to print out the values of the following mathematical expressions:
15 + 4
15 / 4
15.0 / 4.0
15.0 / 4
15 % 4
4 - 8 * 3
(4 - 8) * 3
0.1 + 0.2 - 0.3
Think about the above behavior and be prepared to answer the following questions:
Explain the difference (or lack of it) in the result of 15 / 4, 15.0 / 4.0 and 15.0 / 4.
Explain the difference (or lack of it) in the result of 4 - 8 * 3 and (4 - 8) * 3.
Explain the result of 0.1 + 0.2 - 0.3
Overview of Simple String Methods
You TA will discuss the follow String methods:
length() of the string
indexOf() the comma character
charAt() the first letter in the string
substring() containing the third up to (not including) the seventh characters
toUpperCase() of the string
toLowerCase() of the string
Today's assignment
IMPORTANT: This code is what will be graded. Comment out all previous work before
submitting (using: // or /* */). You are free to borrow code that you've already written.
If you have any doubts or questions, ask the TA:
A) Create a Scanner object.
B) Create an integer variable called i and initialize it to 0.
C) Create a double variable called d and initialize it to 0.0.
D) Do the following two things:
Print the prompt "Enter an integer: " using System.out.print().
Use the Scanner object you created to read in an integer to i.
E) Print "You entered: " followed by the value of the integer variable i.
F) Do the following two things:
Print the prompt "Now enter a double: " using System.out.print().
Use the Scanner object you created to read in a double to d.
G) Print "Now you entered: " followed by the value of d, formatted to two decimal places.
H) Create a String variable myString and initialize to "Babushka".
I) Print the result of calling length() on myString.
J) Print the result of calling charAt() on myString to print third character in myString.
K) Print the result of calling indexOf() on myString to print the index of 'k' in myString.
L) Print the result of calling toUpperCase() on myString.
Make sure your R2.java compiles and produces the correct output.
Check your R2.java using preliminary testing on the Checkin tab.
You must submit your R2.java program using the Checkin tab on the course website.
