format query

[gunjan khanuja]

public class ProjectNew
{


public static void main(String[] args)
{
double d = 12.345;


System.out.printf("|%7f| \n", d);


System.out.printf("%02.2f%s%b",new Double(7),"gg",false);
}
}

According to my understanding the output should be |12.3450| but after running the code i get |12.345000| .Please explain why is this so??
Also in the second statement how is false related to %b.when should i get true and when should i get false as the output.Please explain with example?

[Md. Minhajur Rahman]

For float number, If the precision is not specified then the default value is 6. so the output is |12.345000|.
If the precision is specified, that is used. As your 2nd case, precision is 2. so output is 7.00ggfalse. false is printed as you pass false as argument. if you pass true, true will be printed.

[Tim McGuire]

you did not specify precision in your code:
you did "%7f"
so the following rule applies:
The number of digits in the result for the fractional part of m or a is equal to the precision. If the precision is not specified then the default value is 6. (from http://docs.oracle.com/javase/6/docs/api/java/util/Formatter.html)

if you specify precision:
%2.4f

you would get
12.3450


saying %b tells the formatter put a boolean there and you gave it false so it printed false as output. Instead of false you can give it any boolean expression and it will output it as your %b

for experiment, try

System.out.printf("%02.2f%s%b%b",new Double(7),"gg",false,true);

and

System.out.printf("%02.2f%s true or false: 5 is greater than 2 %b",new Double(7),"gg",5 > 2);