How To Parse A Double From Edittext To Textview? (android)

I'm realy beginning to learn Java. When I run this code everything works fine till I leave my EditText boxes in the from empty and hit the run button. Then I get: ERROR/AndroidRun

Solution 1:

Here is the JavaDoc for java.lang.Double class, parseDouble method:

/**
 * Parses the specified string as a double value.
 * 
 * @param string
 *            the string representation of a double value.
 * @return the primitive double value represented by {@code string}.
 * @throws NumberFormatException
 *             if {@code string} is {@code null}, has a length of zero or
 *             can not be parsed as a double value.
 * @since Android 1.0
 */

Empty values are not considered to be parseable. That's why you get this exception.

You can intoduce an additional check to your code to see if string in the noKids EditText is empty and if so, manually set the value to 0.0:

noKidsStr = noKids.getText().toString();

if(noKidsStr == null || noKidsStr.isEmpty()) {

  etKids = 0.0;

} else {

  etKids = Double.parseDouble(noKids.getText().toString());

}

I suggest writing some sort of convenience utility method that you can re-use for all similar situations in the future.

Solution 2:

you should wrap the Double.parseDouble.. statements in a try/catch clause, to catch any NumberFormatExceptions, and set other values where they fail

edit:

try{
    etKids = Double.parseDouble(noKids.getText().toString());
} catch (final NumberFormatException e) {
    etKids = 1.0;
}
try{
    etGumballs = Double.parseDouble(noGumballs.getText().toString());
} catch (final NumberFormatException e) {
    etGumballs = 1.0;
} 

Solution 3:

Two things you can do: First, only allow numeric data in your EditText field. Actually, I see you already did that. I usually use android:numeric - this is the first I've seen of android:inputType. Thanks for that. =)

Second, ensure that you have text in your EditText with a simple check.

if(noKids.getText().length() > 0)
{
    etKids = Double.parseDouble(noKids.getText().toString());
}

Solution 4:

This is a java question, not an android question.

You should handle the NumberFormat exception in your code. What happens if somebody enters "abc" into the text box? What do you want your app to do? You handle exceptions using try/catch blocks: http://tutorials.jenkov.com/java-exception-handling/basic-try-catch-finally.html

You might also want to check if noKids.getText().toString() is empty before trying to convert it. It might make sense for there to be a different feedback to the user if the string is "" vs if the string is "abc".

Solution 5:

privatevoid calculate() {
         try{
            etKids = Double.parseDouble(noKids.getText().toString());
            etGumballs = Double.parseDouble(noGumballs.getText().toString());
            tvSumIn = etGumballs / etKids; 
          }catch(exception e)
          {
            e.printStackTrace():
          }    
        String thisIsIt = newDouble(tvSumIn).toString();

            if(tvSumIn < 2){
                noSum.setText(thisIsIt + " This is it ");
            }else{
                noSum.setText("This is else");
            }

        }