Java-Input/Output&Streams

• two way to store data
  • text format
    • human-readable
    • sequence of characters
  • binary format
    • data item represent as bytes
• 
• Scanner Class can read input from File or stdin
  • File inFile = new File(“input.txt”);
  • Scanner in = new Scanner(inFile);
  • in.useDelimiter()
    • exp.
      • “[^A-Za-z]+”    ->     al chracter neither capital letter or lower letter will work as delimiter
  • while(in.haveNextLine()){String a = in.nextLine; ….}
    • next(); -> read a word each time, seperate by white space
      • white Spaces
        • ” ” simple space
        • \n newLine
        • \r
        • \t
        • \f
    • nextLine();
      • read entire line and use \n as Delimiter
      • combine with charAt(int) to get sepcific character at a position
      • (!Character.isXX(line.charAt(k))) used to control input as a specific type only each line
      • break string with String.substring(int,int) to get specific part of string
      • remove white space with string.trim
    • hasNextLine();
    • hasNext();
    • nextDouble();
    • nextInt();
  • in.close()
  • control inut type with Character.
    • isDigit -> number
    • isLetter -> upper and lower case letter
    • isUpperCase -> upper case letter
    • isLowerCase -> lower case letter
    • ise WhiteSpace -> ” “, \n, \t…….
• PrintWriter class can used to write text files
  • PrintWriter out =new PrintWriter(“out.txt”)
    • if out.txt exist, it will cleared
    • if not, create a new
    • out.
      • print(“”) int,double,char…
      • println(“”) only to string
      • printf(format,””) control format of output
    • out.close();
  • System.out is a PrintStream object