CODEWITHSUNDEEP
android
Hagogs
Hagogs

Reputation: 53

Number Format Exception "Invalid Double"

I have to build a calculator and i am making some validations, the code is kinda long so i will only put the part that is breaking it.

It is a validation that makes the multiplication, it breaks when trying to multiply a negative number, every other operation is done correctly but the multiplication:

else if(resulttxt.getText().toString().contains("*")){

                String resultarray=resulttxt.getText().toString();
                String[] split=resultarray.split("\\*");
                finalresult = Double.valueOf(split[0]) * Double.valueOf(split[1]);

                if (finalresult<0){
                    negative=true;
                }else{
                    negative=false;
                }
                resulttxt.setText(String.valueOf(finalresult));

resulttxt is received from a TextView that gets it's data from cliking on the numbers or the signs which are also TextViews (not buttons but they do have the On click listener)the operation is done when ciclking on the = sign.

This throws an error if for example i try to do -6*45:

java.lang.NumberFormatException: Invalid double: "6*45"

Like i said everything works with the addition,substraction and division it is only the multiplication that breaks.

Upvotes: 1

Views: 7389

Answers (3)

Benkerroum Mohamed
Benkerroum Mohamed

Reputation: 1936

Try this instead :

 String s1 = resultarray.substring(0,resultarray.indexOf("*"));
 String s2 = resultarray.substring(resultarray.indexOf("*")+1,resultarray.length());

 double d1= Double.valueOf(s1);
 double d2= Double.valueOf(s2);

Hope this helps

Upvotes: 0

Hagogs
Hagogs

Reputation: 53

OMG dudes... this is what was the problem:

I had this validation at the end of the other operations, so BEFORE even going to the multiplication part it entered the "-" validation when it checks 

if(resulttxt.contains("-")){

because it is a negative value so it does have a "-"... so it entered as a substraction instead as a multiplication because of that...

To solve it i had to put the substraction validation at the bottom of all of them.

So thank you for the guys who suggested me to check the line where the error was thrown i wouldn't have known logcat actually tells you were the mistake is and to my surprise it was on the substraction validation which to me was a "WTF" moment and then i realized what i just told you.

Upvotes: 1

Ashray P. Shetty
Ashray P. Shetty

Reputation: 700

I tried executing your code in the compiler :

String resulttxt = "-6*45";
     boolean negative = false;
     if(resulttxt.contains("*")){

            String resultarray=resulttxt;
            String[] split=resultarray.split("\\*");
            double finalresult = Double.valueOf(split[0]) * Double.valueOf(split[1]);

            if (finalresult<0){
                negative=true;
            }else{
                negative=false;
            }
    System.out.println(finalresult);
     }

Every thing worked fine for, please verify datatype used in your program.

addition, multiplication and division works fine. "-6+45, -6*45 and -6/45"(any other combination. I just used the same)

However for subtraction as the pattern is "-6-45" the above logic will fail and throw number format exception. This is because if you split "\-", the "-" is first character in string and there is nothing before it.

Thus your split will fail. So to avoid this you can always take last index of character to split using substring function.

Upvotes: 2

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