如何在Java字符串中定义是否大于

Question

In the following method I need to define that only set the value if its not null and if the value is greater than "0.00" How do I define that.

 String postagePaid1 = trackInfo.getPostage();
                    if(postagePaid1 != null && ????) {
                        claim.setClPtsPostageFee(new BigDecimal(postagePaid1));
                    }

Answer 1

You can't do numeric comparisons with Strings as it doesn't make sense in the String world, only with numbers. So first check that it's not null, and if not, convert it to a double via Double.parseDouble(...)

if (someStr != null && !someStr.trim().isEmpty()) {
  try {
    double someNumber = Double.parseDouble(someStr.trim());
    if (someNumber > 0.0) {
       // ***** here you are ****
    }
  } catch (NumberFormatException nfe) { 
      // some action if String is not numeric
  }
}

Answer 2

Don't use String values as doubles during comparison. String comparison is done in natural order , so "1111" will be lesser than "9" .

In your case, use Double.parseDouble(doubleString) and then compare values.

Answer 3

if postagePaid1 contains only double type value ,you have to convert the string to double type by using following code in order to be able to do comparison

Double.parseDouble(postagePaid1)

so if statement become :

 if(postagePaid1 != null && Double.parseDouble(postagePaid1)>0.00) {