class Decimal Format

1
class Decimal Format

• Import package java.text
• Create DecimalFormat object and initialize
• Use method format
• Example
• import java.text.DecimalFormat
• DecimalFormat twoDecimal new
  DecimalFormat("0.00")
• twoDecimal.format(56.379)
• Result 56.38

2
File Input/Output

• File area in secondary storage used to hold
  information
• class FileReader is used to input data from a
  file
• class FileWriter and class PrintWriter send
  output to files

3
File Input/Output

• Java file I/O process
• Import classes from package java.io
• Declare and associate appropriate variables with
  I/O sources
• Use appropriate methods with declared variables
• Close output file

4
Reading from System.in

• System.in is a predefined input data stream that
  is by default assigned to the keyboard
• System.in is an object of type InputStream
• Remember to import necessary java.io classes
• BufferedReader keyboard
• new BufferedReader( new InputStreamReader(System.
  in) )
• Note that
• BufferedReader( Reader inputReader)
• InputStreamReader( InputStream inputStream)

5
Inputting (Reading) Data from a File

• Import Necessary classes from java.io
• Declare and associate variables with the input
  sources Create BufferedReader Object to read
  entire line
• Use class FileReader
• Specify file name and location
• Use appropriate method to input data
• ReadLine()

BufferedReader inFile new BufferedReader(new
FileReader("a\\prog.dat"))
6
Writing to System.out

• System.out is a predefined output data stream
  object that is by default assigned to the console
• System.out is an object of type PrintStream
• Information is printed to the console using the
  methods below (associated with System.out)
• System.out.println( stringExp )
• System.out.print( stringExp )
• System.out.flush( stringExp )

7
Outputting (Printing) Data to a File

• Import Necessary classes from java.io
• Declare and associate variables with the output
  sources Create PrintWriter Object
• Use classes FileWriter and PrintWriter
• Specify file name and location
• Use appropriate methods to input data
• outFile.println, outFile.print, outFile.flush
• Close output file
• outFile.close()

PrintWriter outFile new PrintWriter(new
FileWriter("a\\prog.out"))
8
Skeleton of I/O Program