Java charAt() String index out of range: 0

Question

I have this code :

private void submitPstart() {

    if (tStock.getText().charAt(0)>='A' && tStock.getText().charAt(0)<='Z'){


    }else {
        errorBox ("Uppercase A-Z");
    }

    tStock.setText("");
    tStock.setFocus();
}

THis is working but when I try not to put anything on the textbox and press the OK button it crashes. It says:

java.lang.StringIndexOutOfBoundsException: String index out of range: 0

and it pointed out to this part: if (tStock.getText().charAt(0)>='A' && tStock.getText().charAt(0)<='Z')

Any help is appreciated. Thanks

Answer 1

You need to check if getText() returns a 0-length (i.e. empty) string.

If it does, then don't try to pull the first character out! (via charAt())

Note that your commented-out check for length() should occur prior to the existing character check.

You may want to check for a null string being returned as well, depending on your framework/solution etc. Note the Apache Commons StringUtils.isEmpty() method, which performs this check concisely.

Answer 2

you must check null and length greater than 0.

 if (tStockPIStart!=null && tStockPIStart.getText().length()>0 && tStockPIStart.getText().charAt(0)>='A' && tStockPIStart.getText().charAt(0)<='Z'){