If I have the following decimal point numbers:
Double[] numbers = new Double[] {1.1233, 12.4231414, 0.123, 123.3444, 1.1}; for (Double number : numbers) { System.out.println(String.format("%4.3f", number)); } Then I get the following output:
1.123 12.423 0.123 123.344 1.100 What I want is:
1.123 12.423 0.123 123.344 1.100 The part that can be a bit confusing is that String.format("4.3", number)
the 4 represents the length of the entire number(including the decimal), not just the part preceding the decimal. The 3 represents the number of decimals.
So to get the format correct with up to 4 numbers before the decimal and 3 decimal places the format needed is actually String.format("%8.3f", number).
You can write a function that prints spaces before the number.
If they are all going to be 4.3f, we can assume that each number will take up to 8 characters, so we can do that:
public static String printDouble(Double number) { String numberString = String.format("%4.3f", number); int empty = 8 - numberString.length(); String emptyString = new String(new char[empty]).replace('\0', ' '); return (emptyString + numberString); } Input:
public static void main(String[] args) { System.out.println(printDouble(1.123)); System.out.println(printDouble(12.423)); System.out.println(printDouble(0.123)); System.out.println(printDouble(123.344)); System.out.println(printDouble(1.100)); } Output:
run: 1,123 12,423 0,123 123,344 1,100 BUILD SUCCESSFUL (total time: 0 seconds) Here's another simple method, user System.out.printf();
Double[] numbers = new Double[]{1.1233, 12.4231414, 0.123, 123.3444, 1.1}; for (Double number : numbers) { System.out.printf("%7.3f\n", number); } 
%8.3f, at least on my computer.
123.344 its length is about 7, it's the minimum you should reserve in your printf format.