printf, multiple flags

[Paul Stat]

So the format of a printf argument is like so

%[arg_index$][flags][width][.precision]conversion char

"-" left justify
"+" include a sign
"(" put negative numbers in parentheses
"0" pad with zeroes
"," include locale specific seperators

b: boolean
c: character
d: digit
f: float
s: string

the flags seems to imply you can have multiple flags, if however I try the following it causes an exception. Can only one flag be set at a time?

System.out.printf("%1$-010.2f",12.50); //left justify, pad with zeroes, width of 10, precision of 2

[M Srilatha]

Hi,

It seems the combination of '-' and '0' is illegal.
Got to know from the API documentation.

Its given:
If both the '-' and '0' flags are given then an IllegalFormatFlagsException will be thrown.

Even i am not sure why this combination is illegal.

Refer to java API doc of Formatter class for more info!

Hope this helps!

[Sagar Rohankar]

Paul Stat wrote:
the flags seems to imply you can have multiple flags, if however I try the following it causes an exception. Can only one flag be set at a time?

System.out.printf("%1$-010.2f",12.50); //left justify, pad with zeroes, width of 10, precision of 2

It throws "IllegalFormatFlagsException: Flags = '-0'", and what are you doing, is something illogical and can't be used, like the flag "0", padded with zeroes, fills the empty left hand side space with zeroes and at the same time you are telling JVM, to display that numbers from left.. How can this two things possible at the same time, that's why "IllegalFormatFlagsException: Flags = '-0'" exception..

When I tried the other flag combination, It works..

 System.out.printf(">>%+010.2f<<",12.50);
//  left justify, add '=' sign, width of 10, precision of 2  

[Wrong exception written]

[Sagar Rohankar]

M Srilatha wrote:
Its given:
If both the '-' and '0' flags are given then an IllegalFormatFlagsException will be thrown.

Particularly, its written here in JavaDocs.

[Aakash Goel]

In printf, does the does width have any significance?

        System.out.printf("%1.3f\n",7654321.23456789);
        System.out.printf("%2.3f\n",7654321.23456789);
        System.out.printf("%3.3f\n",7654321.23456789);
        System.out.printf("%1f\n",7654321.23456789);
        System.out.printf("%2f\n",7654321.23456789);
        System.out.printf("%3f\n",7654321.23456789);

output:

7654321.235
7654321.235
7654321.235
7654321.234568
7654321.234568
7654321.234568

[Aakash Goel]

for floats, that is.

[Michael Angstadt]

Aakash Goel wrote:In printf, does the does width have any significance?

System.out.printf("%1.3f\n",7654321.23456789);
output:
7654321.235

If the length of your number exceeds the specified width, then it's the number's length that takes importance. So even though the first printf() statement specifies a width of 1, the number itself takes up 11 characters, so the width is ignored.

[Aakash Goel]

Michael Angstadt wrote:
If the length of your number exceeds the specified width, then it's the number's length that takes importance. So even though the first printf() statement specifies a width of 1, the number itself takes up 11 characters, so the width is ignored.

Thanks a lot Michael. This happens with integers too!

Now I get the point.