Java: Double % formatting question for printf

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\n", bal, nm);

..an exception is thrown telling me that %d != lang.double. Ideas?

Answer 1

%d is for integers use %f instead, it works for both float and double types:

double d = 1.2;
float f = 1.2f;
System.out.printf("%f %f",d,f); // prints 1.200000 1.200000

Answer 2

Yes, %d means decimal, but it means decimal number system, not decimal point.

Further, as a complement to the former post, you can also control the number of decimal points to show. Try this,

System.out.printf("%.2f %.1f",d,f); // prints 1.20 1.2

For more please refer to the API docs.