Javafx eclipse Text Input Validate when numeric or Mixed and reject when Non-numeric

Question

In JavaFx eclipse application, before saving the data in SQL data base, it is required to verify following conditions: Either Numeric Value or Mixed. But,reject if purely non-numeric with(out) special characters like JHGYyree. Allowed text: 1234, A1254, b64A8 (Ignore Case) Not Allowed: aasdrgf, ASDSA, Asxss, @#vdvd, @33KJJJ, #@878sasa.

The data entered is to be checked after pressing Enter key or Mouse click on Save Button. How to write such a function in JavaFX ?

     @FXML
     private Label lblOffName;

     Boolean static input_validation == false;
     String id = txtOffName.getText();

     if(validate_text(id) == true){

    }
    public Boolean validate_text(String str){
    // validation code here ...
   return input_validation;
   }

Answer 1

Example

An example solution using a loop (assumes a basic English character set). You could use regex instead, but I leave that as an exercise for the reader.

package application;

public class InputValidator {

    public static void main(String[] args) {
        String[] testData = {
                // valid 
                "1234", "A1254", "b64A8",
                // invalid
                "aasdrgf", "ASDSA", "Asxss", "@#vdvd", "@33KJJJ", "#@878sasa"
        };

        for (String input: testData) {
            validate(input);
        }
    }

    /**
     * Either Numeric Value like or Mixed. 
     * But, to reject if purely non-numeric with(out) 
     * special characters like JHGYyree.
     *
     * @param input string to validate
     * @return true if the input string is value.
     */
    private static boolean validate(String input) {
        boolean hasDigit = false;
        boolean hasAlpha = false;
        boolean hasSpecial = false;

        for (int i = 0; i < input.length(); i++) {
            char c = Character.toLowerCase(input.charAt(i));

            if (isDigit(c)) {
                hasDigit = true;
            }

            if (isAlpha(c)) {
                hasAlpha = true;
            }

            if (!isDigit(c) && !isAlpha(c)) {
                hasSpecial = true;
            }
        }

        boolean isValid =
                (hasDigit && !hasAlpha && !hasSpecial) || (hasDigit && hasAlpha && !hasSpecial);

        System.out.println(input + " > " + isValid);

        return isValid;
    }

    private static boolean isDigit(char c) {
        return '0' <= c && c <= '9';
    }

    private static boolean isAlpha(char c) {
        return 'a' <= c && c <= 'z';
    }
}

Output

1234 > true
A1254 > true
b64A8 > true
aasdrgf > false
ASDSA > false
Asxss > false
@#vdvd > false
@33KJJJ > false
#@878sasa > false

Integration with JavaFX

I will also leave this as an exercise for the reader.

Either you can write the integration code yourself, or leverage a validation framework such as:

• ControlsFX Validation
• MaterialFX validation