Question

There is iOS US2FormValidator library for user input validation (see the picture below). I think that library is better than the default of just popping an alert when something doesn’t validate.

I’m looking for how to do such things on Android. Are there some Android analogs of US2FormValidator?

Answer 1

The pop-up effect you have shown on your screenshot can be achieved using Android’s built-in setError(String) method on EditText widgets.

Also, you can leverage the power of annotations using the Android Saripaar library that I’ve authored.

first add the library:

compile 'com.mobsandgeeks:android-saripaar:2.0.2'

The library is very simple to use. In your activity annotate the View references you would like to validate as in the following example.

@Order(1)
private EditText fieldEditText;

@Order(2)
@Checked(message = "You must agree to the terms.")
private CheckBox iAgreeCheckBox;

@Order(3)
@Length(min = 3, message = "Enter atleast 3 characters.")
@Pattern(regex = "[A-Za-z]+", message = "Should contain only alphabets")
private TextView regexTextView;

@Order(4)
@Password(min = 6, scheme = Password.Scheme.ALPHA_NUMERIC_MIXED_CASE_SYMBOLS)
private EditText passwordEditText;

@Order(5)
@ConfirmPassword
private EditText confirmPasswordEditText;

The order attribute specifies the order in which the fields have to be validated.

In your onCreate() method instantiate a new Validator object. and call validator.validate() inside any of your event listeners.

You’ll receive callbacks on onSuccess and onFailure methods of the ValidationListener.

If you want to show a pop-up as show in the image above then do the following,

public void onValidationFailed(View failedView, Rule<?> failedRule) {
    if (failedView instanceof Checkable) {
        Toast.makeText(this, failedRule.getFailureMessage(), Toast.LENGTH_SHORT).show();
    } else if (failedView instanceof TextView) {
        TextView view = (TextView) failedView;
        view.requestFocus();
        view.setError(failedRule.getFailureMessage());
    }
}