要转换的字符串

Question

I need to convert a string with value 12.10 to a float value without losing the zero. How can I achieve this in Java.

Answer 1

if you aren't worried about memory then

    String str = "12.00";
    BigDecimal bd=  new BigDecimal(str);
    System.out.println(bd);//12.00

Answer 2

a) It makes no sense to store trailing zeroes in a float.

b) 12.1 will not map precisely to a floating point value (although this may not be immediately apparent)

Answer 3

From Bloch, J., Effective Java, 2nd ed, Item 48:

The float and double types are particularly ill-suited for monetary calculations because it is impossible to represent 0.1 (or any other negative power of ten) as a float or double exactly.

For example, suppose you have $1.03 and you spend 42c. How much money do you have left?

 System.out.println(1.03 - .42); 

prints out 0.6100000000000001 .

The right way to solve this problem is to use BigDecimal , int or long for monetary calculations.

Example:

BigDecimal price =  new BigDecimal("12.10");

Answer 4

Use a java.text.DecimalFormat :

DecimalFormat fmt = new DecimalFormat("0.00");
double floatval = fmt.parse("12.10").doubleValue();
String sval = fmt.format(floatval);