How to append a + sign before positive numeric values?

Adding the + flag appends a + sign before positive numeric values.

For example,

import java.util.Formatter;
public class Main {
public static void main(String args[]) {
Formatter fmt = new Formatter();
// Right justify by default
fmt.format("%+d", 100);
System.out.println(fmt);
}
}
The output:

100