How to limit decimal places... ...Math.round()??

[MissouriTiger]

How can I limit the fractional decimal places of a double? I found an old post on this forum which suggests Math.round(). But that returns a long, which isn't even a floating point type. As a simple example, how might I limit the following output to 1 fractional decimal place?

System.out.print
(absoluteError = Math.abs(guessWt - realWt));

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[Targol]

May be the best way to achieve is to build your own function combining the Double.toString method and a stringTokenizer like this :

public String cutDecimals(Double dblValue, int nbDecimals) {
  String tmp = Double.toString(dblValue);
  StringTokenizer st = new StringTokenizer(tmp, ".", true); 
  // or "," (in function of your locals settings)
  String returnStr = st.nextToken() + st.nextToken() + st.nextToken().subString(0, nbDecimals - 1);
  return returnStr;
}

Beware : I didn't put any exception trap in this code. Water is not bad as soon as it stays out human body ;-)

 

[Otto]

Try this:
System.out.print(absoluteError=
((double) Math.round(Math.abs(guessWt-realWt)*10))/10));

If you want other than 1 dec, change the constants (10) into a variable.

Otto

 

[MissouriTiger]

Actually I already discovered a diferent way:

Declare-
DecimalFormat df1 = new DecimalFormat("####.00"

Then,

df1.format(arrayGuessWt)


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