Chapter 3 InputOutput 2 Objectives Apply formats currency

Chapter 3 Input/Output

2 Objectives • Apply formats (currency and percentages) to output. • Use keyboard input in Java program to create interactivity. • Use dialog box input/output in Java program to create interactivity. • Associate import statements with corresponding input/output/format classes/packages. Copyright © 2018 Daly & Wrigley

3 Scanner Class Input data from the Java console: Value Returned Method Returns… byte next. Byte() Input as a byte. short next. Short() Input as a short. int next. Int() Input as an integer. long next. Long() Input as a long. float next. Float() Input as a float. double next. Double() Input as a double. boolean next. Boolean() Input as a boolean. String next() Next word as a String next. Line() Input line as a String. Note: In order to use this class, you must use the following import statement: import java. util. Scanner; Copyright © 2018 Daly & Wrigley

4 Scanner Age Example: Copyright © 2018 Daly & Wrigley

5 Scanner Addition Example: Copyright © 2018 Daly & Wrigley

6 Input Dialog Boxes An input dialog box asks a question and uses a box for entering a response. String response = JOption. Pane. show. Input. Dialog(null, "Enter Fahrenheit"); If this data is to be used in a calculation, it will need to be converted from String data to double data or integer data with one of the following statements: double fahrenheit = Double. parse. Double(response); Note: In order to use this class, you must use the following import statement: import javax. swing. JOption. Pane; Copyright © 2018 Daly & Wrigley

7 Message Dialog Boxes Uses a simple window to display (output) information. JOption. Pane. show. Message. Dialog(null, "Fahrenheit: " + fahrenheit + "n. Celsius: " + celsius); Note: In order to use this class, you must use the following import statement: import javax. swing. JOption. Pane; Copyright © 2018 Daly & Wrigley

8 JOption. Pane Addition Example Copyright © 2018 Daly & Wrigley

9 JOption. Pane Addition Output Copyright © 2018 Daly & Wrigley

10 Number. Format Class • Used to format output as currency. • Currency Example: Number. Format currency. Formatter = Number. Format. get. Currency. Instance( ); System. out. println(currency. Formatter. format(20. 5) ); Output: $20. 50 Note: In order to use this Number. Format class, you must use the import statement: import java. text. Number. Format; Copyright © 2018 Daly & Wrigley

11 Decimal. Format Class Used to format output with a specific number of digits before and after the decimal point. Character 0 #. , % Meaning Required digit. Print 0 if there isn’t a digit in this place. Optional digit. Leave blank if there isn’t a digit in this place. Decimal point separator. Comma separator. Multiplies the result by 100 and displays a percent sign. double fahrenheit = 212. 5; Decimal. Format pattern. Formatter = new Decimal. Format ("#, ###. 00"); System. out. println(“The temperature is “ + pattern. Formatter. format(fahrenheit)); Output: The temperature is 212. 50 Note: In order to use this Number. Format class, you must use the following import statement: import java. text. Decimal. Format; Copyright © 2018 Daly & Wrigley