How to center string output using printf() and variable width?

Question

I'm creating an output in Java using printf() to create table headers. One of the columns needs variable width.

Basically it should look like this:

//two coords
Trial    Column Heading
1        (20,30)(30,20)
//three coords
Trial        Column Heading
1        (20,40)(50,10)(90,30)

I tried to use:

int spacing = numCoords * 7; //size of column
printf("Trial    %*^s", column, "Column Heading");

But I keep getting output errors when I try to use * or ^ in the conversion statement.

Does anyone have any idea what the correct formatting string should be?

Answer 1

Use StringUtils.center from the Commons Lang library:

StringUtils.center(column, "Column Heading".length());

Answer 2

Java does not support the "*" format specifier. Instead, insert the width directly into the format string:

int spacing = numCoords * 7; //size of column
System.out.printf("Trial    %" + spacing + "s", "Column Heading");