Question

Say you have some tabular data where the datas length can vary, is there a provision with the Formatter class to auto adjust the padding?

So instead of this (note column A):

columnA    columnB     
1            34.34          
10            34.34
100            34.34          
1000            34.34

You get this (note column B):

columnA    columnB     
1            34.34          
10           34.34
100          34.34          
1000         34.34

Thus far, i’ve tried this which only simply includes the spaces between %5s %5s, but they are static and do not adjust to produce the results I want. I was under the impression that the 5 in %5s would auto pad 5 spaces

Formatter formatter = new Formatter();
formatter.format("%5s     %5s", columnAdata, columnBdata);

Answer 1

It’s definitely possible. The way I know off-hand is to configure a minimum width for data in your first column. To do this you want to make use of the width attribute in conjunction with left-justification (both documented in the Javadoc). Here’s a start for you:

System.out.printf("%-10d %d%n", 1, 100);
System.out.printf("%-10d %d%n", 10, 100);
System.out.printf("%-10d %d%n", 100, 100);

This prints:

1          100
10         100
100        100

The format %-10d %d%n can be explained as follows:

%-10d: first field

    %: start field
    -: left-justify
   10: output a minimum of 10 characters
    d: format as a decimal integer

%d: second field, using defaults for decimal integer
%n: newline