print spaces with String.format()

Question

You need to specify the minimum width of the field.

String.format("%" + numberOfSpaces + "s", "");

Why do you want to generate a String of spaces of a certain length.

If you want a column of this length with values then you can do:

String.format("%" + numberOfSpaces + "s", "Hello");

which gives you numberOfSpaces-5 spaces followed by Hello. If you want Hello to appear on the left then add a minus sign in before numberOfSpaces.