Thread: Decimals going too far

I had to make a table showing different values for converting kg to lbs and I'm confused because when it compiles, some of the decimals show correctly and some of them show with several 0's added on with another number on the end. Please help, I've tried to do math.random, but I'm not sure how to tie it in with my program. Please help.

//1 kg = 2.2 lbs
public class kg_to_lbs {
	public static void main(String[] args) {
//not sure if values are needed..
	int kg = 1;
	double lbs = 2.20; 
 
//Table title
	System.out.println("   Kilograms to Pounds");
 
//First line headings
	System.out.println("  Kilograms   |   Pounds  ");
//do-while loop	
do {
		System.out.println("      " + kg + "       |    " + (kg * lbs) + "  ");
		kg++;
	}
while (kg <= 199);
//end loop
	}	
}

and this is some of the results I get

      1       |    2.2  
      2       |    4.4  
      3       |    6.6000000000000005  
      4       |    8.8  
      5       |    11.0  
      6       |    13.200000000000001

show with several 0's added on with another number on the end.

There are many ways to get rid of that.

One way
Is to use DecimalFormat class.
There are API that can help you with your error
(see the link: http://docs.oracle.com/javase/7/docs...malFormat.html)

Other way
Convert/Cast your answer to float.
it's either store your answer into float type variable,
or if your variable is in double type variable, just cast it to float when printing:
example:

double answer = 3 * 2.20;
System.out.println((float) answer);

I think float data type has only one decimals.

Other way
you can also use substring. Just convert you decimal result to
String and used substring, you can use the index of dot ( . )
as reference on how many decimals you want to get.

And there are other ways,

I put converted to float, but sadly, I was unable to get the decimals all the way down to 1 decimal point. And the DecimalFormat class won't work for me, might've been the way I was putting it though. Thanks anyway!

Instead of println method to print your output, format your output using printf method like this,

System.out.printf("%d  | %.2f\n",kg,kg*lbs);