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javajtextfieldvalidation

Check if a JTextField is a number

quick question: I have a JTextField for user input, in my focus listener, when the JTextField loses focus, how can I check that the data in the JTextField is a number? thanks

Solution

  • Try performing Integer.parseInt(yourString) and if it throws a NumberFormatException you'll know the string isn't a valid integer

    try {
     Integer.parseInt(myString);
     System.out.println("An integer"):
}
catch (NumberFormatException e) {
     //Not an integer
}

    Another alternative is Regex:

    boolean isInteger = Pattern.matches("^\d*$", myString);