How to check a text field

lad12

I want to check to see if the data entered in a text field is a double..if it is i want to write to the file..if it is a string den i want the program to catch the error and not write any data to the file.

at the moment this is what i have written

try{
setMinimumLevel((double)makeDouble(minimumLevelField.getText()));
}
catch(NumberFormatException exp)
{
stockMinimumLevelField.setText("");
a = ("Please enter double in Minimum Level. ");
}

how can i check on this line
setMinimumLevel((double)makeDouble(minimumLevelField.getText()));

aidan_walsh

C++, C#, Java, none of the above?

lad12

sorry java

mr_angry

IIRC there's an "IsDouble()" method on the double class itself.

I could be wrong though.

aidan_walsh

If you can, use Double.parseDouble(String s) which will return a double value to you.

But, as I suspect that this is an assiagnment on method writing more than anything else, just return the double value back out. If an exception this thrown, you'll jump to that, but if not just continue to write the value to file.

scojones

Go to http://www.javadoconline.com and search for "java.lang.Double". Happy reading.

lad12

But, as I suspect that this is an assiagnment on method writing more than anything else, just return the double value back out. If an exception this thrown, you'll jump to that, but if not just continue to write the value to file

I already have created a method called make double..this changes the text to a double..but i want to check to see if 4 of the text fields are doubles..if they aint then i dont want to write anything to the file..how can i exit after the exception has been caught without exiting the program altogether.
I created a blank method(blanks the text fields) so i can call this when the exception is caught but it writes 0's to the file.

aidan_walsh

Ok, here are a few hints... Boolean returns, if, loop.

scojones

Another way of doing this http://java.sun.com/j2se/1.4.2/docs/api/java/lang/Character.html#getType(char)

GreeBo

lad12 wrote:

I already have created a method called make double..this changes the text to a double..but i want to check to see if 4 of the text fields are doubles..if they aint then i dont want to write anything to the file..how can i exit after the exception has been caught without exiting the program altogether.
I created a blank method(blanks the text fields) so i can call this when the exception is caught but it writes 0's to the file.

so you want to loop 4 times while some check is true
if its false then you want to stop and set an error message

Always try to think these things out in your head first and then "just" code it..