Announcements

1
Announcements

• Quiz 2 Grades Posted on blackboard

2
Files

• Data in Main Memory is volatile
• File Place for permanent data storage
• C drive, A drive, Flash drive, etc.

Main Memory
File
main() int num string firstname
Disk
3
Scanner Input

• Scanner scan new Scanner(System.in)
• while (scan.hasNextInt())
• i scan.nextInt()
• // System.in is the keyboard file

4
Input Files
data.txt file

• import java.io.
• import java.util.Scanner
• class FileInput
• public static void main(String args) throws
  IOException
• File ifile new File("data.txt")
• Scanner scan new Scanner(ifile)
• while (scan.hasNextInt())
• i scan.nextInt()

17 6 432
5
Display Output

• for (i0i lt 100 i i 2)
• System.out.println(i)
• // System.out is the display window file

6
Output File Streams
data2.txt
0 2 98

• import java.io.
• class FileOutput
• public static void main(String args) throws
  IOException
• int i
• FileOutputStream ofile new FileOutputStream("da
  ta2.txt",false) //trueAPP
• PrintWriter pw new PrintWriter(ofile)
• for (i0i lt 100 i i 2)
• pw.println(i)
• pw.close() // Writes data to file on disk

7

• import java.util.Scanner
• import java.io.
• class FormatFileData
• public static void main(String args) throws
  IOException
• int loops, integer, i
• float decimal
• String name
• File ifile new File("mydata.txt")
• Scanner scan new Scanner(ifile)
• loops scan.nextInt()
• for(i 0 i lt loops i)
• integer scan.nextInt()
• decimal scan.nextFloat()
• name scan.next()

mydata.txt file 5 8 9.3 Jon 6 14.335 Bill 0
35.67e9 Mary -23 -4.55 Smith -3 -4e3 xyz
Output
8 9.3 Jon 6 14.335 Bill 0 3.567E10 Mary -23
-4.55 Smith -3 4000.0 xyz