formatter

Formatter

Formatting Numbers

• Two classes can be used to format and parse numbers,

  • java.text.NumberFormat:

    • Used to format a number in a particular locale’s predefined format,

  • java.text.DecimalFormat:

    • Used to format a number in a format of your choice in a particular locale,
    • Provides advanced formatting,
• Ex(NumberFormat): see numberFormat() in Test.java,

  private static void numberFormat(){
  
      //------------   default locale USA -----------
      NumberFormat format = NumberFormat.getNumberInstance();
  
      double num = 175570;
      String sn = format.format(num);
      System.out.println(sn); // 175,570
  
      NumberFormat format1 = NumberFormat.getCurrencyInstance();
  
      double num1 = 175570;
      String st = format1.format(num1);
      System.out.println(st); // $175,570.00
  
      //-------------------   BD locale --------------
      NumberFormat format2 = NumberFormat.getNumberInstance(new Locale("en","BD"));
  
      double num2 = 175570;
      sn = format2.format(num2);
      System.out.println(sn); // 175,570
  
      NumberFormat format3 = NumberFormat.getCurrencyInstance(new Locale("en","bd"));
      st = format3.format(num);
      System.out.println(st); // BDT175,570.00
  }

• Ex(DecimalFormat): see decimalFormat() in Test.java,

  private static void decimalFormat(){
      double num = 175.570354;
  
      String pattern = "####.####"; // my custom pattern
      DecimalFormat format = new DecimalFormat();
      format.applyPattern(pattern); // applying my pattern
  
      String sn = format.format(num);
      System.out.println(sn); // 175.5704
  
      pattern = "0000.0000";
      format.applyPattern(pattern);
  
      sn = format.format(num);
      System.out.println(sn); // 0175.5704
  
  
      num = -125.53;
      pattern = "#.##";
      format.applyPattern(pattern);
  
      sn = format.format(num);
      System.out.println(sn);// -125.53
  
  
      num = 12.53;
      pattern = "#.##;(#.##)"; // left part of semicolon is for positive number, right part for negative number
      format.applyPattern(pattern);
      sn = format.format(num); System.out.println(sn); // 12.53
  
      num = -12.53;
      sn = format.format(num); System.out.println(sn); // (12:53)
  }

Printf-style Formatting

• java.util.Formatter class supports printf-style formatting,
• Similar to printf() in C,
• Ex: See printfStyleFormatting() in Test.java,

  private static void printfStyleFormatting(){
      // Formatting strings
      System.out.printf("%1$4s, %2$4s, and %3$6s %n", "Fu", "Hu", "Lo"); //  Fu,   Hu, and     Lo
  
      //formatting numbers
      //takes space on left side
      System.out.printf("%1$4d, %2$4d, %3$4d %n", 10, 100, 1000); //  10,  100, 1000
  
      //takes space on right side
      System.out.printf("%1$-4d, %2$-4d, %3$-4d %n", 1, 10, 100); //1   , 10  , 100
  }

• %1$4s:
  • 1 means it will use the first string provided by user. "Fu" for 1st println(),
  • 4 means total 4 character will be taken.
    • Space will be added on left(4),
    • Space will be added on right( if negative is used),
  • s means String,

It's disturbing. Learn yourself if you want more. Not really useful.