Form Validator Library for Android
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Form Validator Library for Android


Form Validator Library for Android is based on Zend_Validator coded in PHP. This library is intended to simplify and streamline the code to validate a form Android. For the moment, the form can just handle the EditText. Other elements will emerge in future versions.



With Android 4.2, the error display has undergone a display bug. Sometimes, the error fields do not appear in the display. I hope that Google will repair this problem quickly due to Android in itself and not the library.


Form Validator Library is composed of 3 members :

  • Form : Contains all beings validates to treat. This is the Form that manages the display of error messages in the various elements.
  • Validate : Contains all the validators to be treated for a given element.
  • Validator : Can define a validation rule.


The validator is basic class for this library. It contains specific validation rules. To instanciate validator, you just have to do this (EmailValidator for example):

new EmailValidator(context);

For some validators, functions can change the validation rules. The validator currently contains three basic validation rules:

  • EmailValidator : Ensures that the field does contain a email address. You can also define a regex to check for a particular domain name with the function setDomainName(DomainRegexp). Example for domain : setDomainName("gmail\\.com").
  • NotEmptyValidator : Ensures that the field is not empty.
  • UrlValidator : Ensures that the field is a valid url.
  • AlnumValidator : Ensure that the feld has Alnum characters.
  • HexValidator : Ensure that the field has Hex characters.
  • RegExpPattern : Ensure that the field does match setted Pattern.
  • Custom Validator : You can create your own Validator. To do this, you can just create class extends AbstractValidator :
public class CustomValidator extends AbstractValidator
    private int mErrorMessage = R.string.validator_custom; // Your custom error message

    public CustomValidator(Context c) {

    public boolean isValid(Object value) {
        // Your validation Test is here.
        // Retour true if it's correct, false if it's incorrect
        return true;

    public String getMessage() {
        return mContext.getString(mErrorMessage);


The pure Validate class is a FIFO validator. It's test a list of AbstractValidator for specific EditText. For some special cases, Validate is not enough. This is why there are specific validates. This is why there are two individuals with a Validate operation different from that base :

  • ConfirmValidate : Can check whether a value is identical between the two fields. Can be used to confirm the entry of a password.
  • OrTwoRequiredValidate : If one of the two target fields has a value, then it is valid. Can be used if a user must give his phone or fax.
  • Validate : The base Validate. It creates his validators stack.

Basicly, Validate can only handle a single EditText. If you want to manage several at the same time, see if **ConfirmValidate ** or **OrTwoRequiredValidate ** match your problem. If this is not the case, you may need to create your own Validate. To instantiate a Validate, you just have to do this:

Validate emailField = new Validate(email);

And to add Validator stack, for example to add a required Email field, you have to do this:

emailField.addValidator(new NotEmptyValidator(mContext));
emailField.addValidator(new EmailValidator(mContext));


The Form class is the class teacher of the whole Library. It is this which manages the processing of each Validate, Validator and displays the error on the EditText automatically. The Form class stores a Validate stack and then you just have to run the validation with the validate() function. To instanciate Form and add Validates, you have to do this :

Form mForm = new Form();

// ...

// Launch Validation
    // success statement
    // error statement like toast, crouton, ...


  • 0.1 : Create library
  • 0.2 : Add ConfirmValidate and OrTwoRequiredValidate
  • 0.3 : Extends EmailValidator with setDomainName()
  • 0.4 : Replace Validator by AbstractValidator
  • 0.5 : Fix bug in UrlValidator
  • 1.0 : Add AlnumValidator, HexValidator, RegExpValidator, ValidatorException. Fix Validate class.