Using Javas System.out.format to align integer values

问题

I am trying to produce right aligned numbers looking a bit like this:

  12345
   2345

but I clearly does not understand the syntax. I have been trying to follow these instructions. and Come up with the following attempt (it is integers so d and I want width 7 and 0 decimals):

public class test {

    public static void main( String[] args ) {
        System.out.format("%7.0d%n", 12345);
        System.out.format("%7.0d%n",  2345);
    }
}

but no matter what I do I seem to end up with IllegalFormatPrecisionException. Is there a way to do this using this tool? If not how else would you do it?

回答1:

You can do something like this:

public class Test {
    public static void main( String[] args ) {
        System.out.format("%7d%n", 12345);
        System.out.format("%7d%n",  2345);
    }
}

Essentially this code asks Java to pad the string with spaces so that the output is exactly 7 characters.

回答2:

Do it like this:

public class test {

    public static void main( String[] args ) {
        System.out.format("%7d%n", 12345);
        System.out.format("%7d%n",  2345);
    }
}

回答3:

From the linked page, it shows this:

System.out.format("%,8d%n", n); // --> " 461,012"

You can omit the comma, and change the 8 to a 7

回答4:

converter %d is for integers and %f is for float. "%7.0d%n" is used with a float(i.e., as %7.0f%n) and "%7d%n" is used for integer representation.this is the reason for IllegalFormatPrecisionException exception.

Reference link http://docs.oracle.com/javase/tutorial/java/data/numberformat.html

来源：https://stackoverflow.com/questions/8215282/using-javas-system-out-format-to-align-integer-values

标签

java

string-formatting