Questions

• Reading?
• Quiz?
• Homework?

Concept - Getting input with Scanner

• Programs are more interesting if we can get user input.
• We will use Scanner class located in java.util.Scanner to get keyboard input
• Must put this statement at the top of your code

  import java.util.Scanner;

• To create a Scanner object

  Scanner scan = new Scanner(System.in);

• You need to prompt the user to tell him what to enter before calling a Scanner method to read input from the keyboard: For eample

  System.out.print("Please enter your name: ");

Concept - Getting input with Scanner

• Scanner has methods to read input
  

  Method name	What it does
  next()	gets the next token in the input stream as a String
  nextInt()	gets the next token in the input stream as a int
  nextDouble()	gets the next token in the input stream as a double
  nextLine()	gets the entire line in the input stream

  
  

Activity - Input

Record your participation in Piazza clicker question Lesson8 Q1

Java Factory is having a sale where everything is being sold at 2/3 of its original cost. Write a program to read price from the keyboard and then calculate and print the new price (Call the new price discountedPrice). Do not use .67. Let Java do the division to get a more acurrate answer

What do you need to do? Here is pseudocode

  create a Scanner
  prompt for a price
  get the next double from the keyboard
  calculate 2/3 of the price 
  print it

 

Here is the skeleton of a project you can use for getting input

Concept - Formatting output

• System.out.printf (param1, param2 ...)
• param1 is a format string that tells how to format the rest of the parameters
• Format string contains a format specifier % followed by other symbols
• Format Specifier Examples
  
  

 

Activity - Formatted Output

Record your participation in Piazza clicker question Lesson8 Q2

Our boss is not happy with the way output looks in the last activity. It looks messy. The boss wants us to modify the previous program to format the discountedPrice with a dollar sign and 2 decimal places. Which of the following statements will do that?

1. System.out.printf("$%10.2f", discountedPrice);
2. System.out.printf("%$.2f", discountedPrice);
3. System.out.printf("$.2f", discountedPrice);
4. System.out.printf("$%10.2d", discountedPrice);
5. System.out.printf("$%.2f", discountedPrice);

 

Activity - Strings

Record your participation in Piazza clicker question Lesson8 Q3

Look at this string:

String city = "San Jose";

S	a	n		J	o	s	e
0	1	2	3	4	5	6	7

• How many characters are in the String? (Count them)
• What is the index of the first character in the String?
• What is the index of the last character in the String.
• What is the first character of the string?
• What is the last character of the string?
• At what index is the first space?

Concept - substring

Often you want just a portion of a string, called a substring. To get a substring, use the following code

str.substring(start, pastEnd)

Given this string:

String str = "Udacity";

U	d	a	c	i	t	y
0	1	2	3	4	5	6

look at these substring examples:

substring	code to extract the substring
U	str.substring(0,1) str.charAt(0)
y	str.substring(6) str.substring(str.length() -1) str.charAt(6) str.charAt(str.length() -1)
Uda	str.substring(0, 3)
city	str.substring(3,7) str.substring(3)

 

Activity - Substrings

Record your participation in Piazza clicker question Lesson8 Q4

Given this declaration:

String word = "University";

What is returned by word.substring(1, 5);

1. Unive
2. Univ
3. nive
4. niver

Activity - Strings

Record your participation in Piazza clicker question Lesson8 Q5

Now assume we have a string of unknown length called text. We know it contains more than one word.

• What code would you use to find out how many characters are in the String text?
• What code would you use to get the first character of a string?
• What code would you use to get the index of the last character in the String.
• What code would you use to get the last character of a string?
• What code would you use to find the index of the first space in the String. That will be the index of the character after the end of the first word (try indexOf)
• What code would you use to get the first word?

 

 

Activity - Program using substring

Record your participation in Piazza clicker question Lesson8 Q6

Write a program that asked the user to enter a String from the keyboard. Print the string and then print the first and last characters. Test using the Strings hello and San Jose

Here is the skeleton of a project to get input

Activity - indexOf

Record your participation in Piazza clicker question Lesson8 Q7

Write a program that asked the user to enter a phrase of 3 words. Print the phrase and then print just the first word and finally print the length of the first word.

The first word is the letters up to the space. You can find the position of the space by using this statement

int indexOfSpace = pharse.indexOf(" ");