A brief in Java string format

When to format a Java String using System.out.printf or System.out.format, The syntax for the format is :

1	%[arg_index$][flags][width][.precision]<conversion_char>

Here are more explanation:

• arg_index    An integer with suffix '$'. begin with 1, not 0. The position of the args.
  
• flags 
  - Left-align, default is right-aligned
  + Include +/-before number
  0 Pad with zeros before number
  , User comma to separate number
  ( Enclose negative numbers in parentheses. '-' will not display
  
• width  The width of the printed String, very useful to get table like output
• precision  For float/double, specify the digits after "."
  
• Conversion_char
  b boolean
  c char
  d integer
  f float/double
  s string

Below is a simple example for demostration

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System.out.printf("<%-3s><%6s><%10s><%10s>\n","Id","Gender","Name","Balance"); System.out.printf("<%3$03d><%2$6s><%1$10s><%4$+10.2f>\n", "Tom","M",1,688.972); // arg_indx System.out.printf("<%03d><%6s><%10s><%+10.2f>\n", 2,"M","Jerry",-12.345); System.out.printf("<%03d><%6s><%10s><%(10.2f>\n", 3,"F","Rose",-12.345);

The "<"  and ">" are added to make the border visible. The outputs are:

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<Id ><Gender><      Name><   Balance> <001><     M><       Tom><   +688.97> <002><     M><     Jerry><    -12.35> <003><     F><      Rose><   (12.35)>