Beginning help with Java

darin3200 · 07-01-2003, 09:28 PM

Currently I am try to write a simple program and I am getting some trouble from the complier. Here is what I have

Code:

class moon {
	public static void main(String args[]) {
int normal;
int moon;
int counter;
counter = 0;
for(normal = 0; normal <= 250; normal = normal+5) {
moon = normal * .17;
System.out.println( + normal + " pounds on earth would be " + moon + " pounds on the moon " );
counter++;
if(counter == 10) {
System.out.println();
counter = 0;
}
}
}
}

now the program will work great when I replace int normal and int moon with double normal and double moon but the problem is i don't want the really long decimals, just rounded numbers. When I try to complie with int instead of double I get this from the complier

Code:

moon.java:8: possible loss of precision
found   : double
required: int
moon = normal * .17;
              ^
1 error

Is there anyway around this?

Tinkster · 07-01-2003, 10:16 PM

Quote:

Originally posted by darin3200

Code:

moon = normal * .17;

I'm not too good with Java, but try:
moon = intValue( normal * .17);

Cheers,
Tink

jpbarto · 07-01-2003, 11:00 PM

Take a look at the Integer and Double classes. I don't have my references with me right now (I usually leave them at work). But the Double class has all kinds of formatting capaiblities.

Such as if you have a double value called dblVal then you could use code such as this...

double dblVal;
int intVal;

*** code to set value of dblVal ***

Double dblClassInstance = new Double (dblVal);
intVal = dblClassInstance.intValue ();

however this WILL cause loss of precision. such that if dblVal = 3.12159 then the resulting intVal may be just 3.

perhaps a better option would be to print a rounded value of 3.12?
or perform some type of formatting in the print statement... while I'm not certain I think I remember reading somewhere that Java println functions can handle to some extent formatting like what is available in C's printf statements.

Check out the class definition / descriptions here:
http://java.sun.com/j2se/1.3/docs/ap...ng/Double.html

here's a link about formatting strings in Java:
http://developer.java.sun.com/develo...mming/sprintf/

hth,
jpbarto

AlaskaLinux · 09-11-2003, 07:54 PM

Java can't put a decimal value into an int ever, so you have to set your normal and moon for double and then at the end convert them to int

Looking_Lost · 09-11-2003, 08:34 PM

As an example this will round my double to 212.24
I

Code:

import java.text.DecimalFormat;

public class dec
{
  public static void main(String args[])
  {


   double myDouble=212.235566;

   DecimalFormat myformat=new DecimalFormat("0000.00");

   String temp=myformat.format(myDouble);

   myDouble=Double.parseDouble(temp);

   System.out.println("My Double is now :" + myDouble);
   }
}