QMCS 230

1
QMCS 230 Today in Class

• Getting Homework Back
• DecimalFormat class - recap
• the printf method
• Revision to Payroll - Lab 6

2
DecimalFormat class

• Convert numbers into strings NICELY
• Control decimal appearance
• Insert commas, force/suppress leading 0s
• import java.text.DecimalFormat
• DecimalFormat twoDecimals
• new DecimalFormat(0.00)

3
Decimal Format Options

• 0 where you ALWAYS want a digit
• Digits to the right indicate rounding
• . Decimal point, if any
• Optional leading digit
• , Comma, like between 3 0s
• ,0.00 commas, always one digit to
• the left of the decimal, exactly 2 digits to the
  right of the decimal
• at end makes percentage (x100)
• Lets do an example

4
the printf method

• A variant of println that does formatting
• Descended from an ill-behaved Unix feature
• I only like it because
• I know it
• Its easy to use
• Bad thing it only works on output
• DecimalFormat works for all strings

5
The printf secret code

• Make a text string
• Embed a code for each number inserted
• d integer decimal
• s string
• f double floating point
• Leading digit spaces to use
• Comma insert commas in a number
• Decimal followed by digit decimal places

6
Revision to Payroll

• Pick a version (Scanner version is best)
• If theres any overtime, ask for authorization
• ASK ONLY ONCE
• Remember the decision
• If not authorized, pay for first 8 hours
• Format the numbers nicely
• Calculate to cents
• Suppress ill-behaved decimal points

7
Creative Commons License

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