Formatting with printf() and format

[harmeet saini]

Hi everyone,

i am beginner in java and preparing for SCJP 1.6, i am following K&B as a study guide , i got stuck in the topic formatted printf and format.

       int i1= -123;
		int i2= 12345;
		System.out.printf("%1$ (7d< \n" , i1);   //1
		System.out.printf(">%0, 7d< \n",i2);    //2
		System.out.format(">%+-7d< \n",i2);  //3
		System.out.format(">%2$b + %1$5d<  \n",i1, false);    

Output:
> (123)<
>012,345<
>+12345 <
>false + -123<


In the above code at line 1 what does 1$ refers to although we have only one argument i1, what does "7d" does eventhough changing the numeric value is not making any difference in the output

In line 2 how does %0 differs from %1$ and how does separator(,) works here

Line 3 giving both + and - results only in + as output

Thanks in advance

[Allain Walker]

Not to be too flippant about it, I think the answers you seek lie here, JavaDocs
Dealing with the Format String Syntax.