Double % formatting question for printf in Java

Question

%s is a string in printf, and %d is a decimal I thought...yet when putting in

writer.printf(\"%d dollars is the balance of %s\\r\\         


        

Answer 1

Yes, %d is for decimal (integer), double expect %f. But simply using %f will default to up to precision 6. To print all of the precision digits for a double, you can pass it via string as:

System.out.printf("%s \r\n",String.valueOf(d));

or

System.out.printf("%s \r\n",Double.toString(d));

This is what println do by default:

System.out.println(d) 

(and terminates the line)