Question

I am trying to find a form validation library in android. Is there such a thing ?

I have a registration form that I want to validate its fields. If the user enters an invalid data, I want to put a red warning mark at the right of the field and pop up a tooltip that he entered an invalid data.

I know about the android:inputType but this is not what I want

Answer 1

I don’t know about any such libraries. But if you are working with EditTexts, then your best option is to use a custom TextWatcher:

class TextCheck implements TextWatcher
{
    private EditText editor;

    public TextCheck(EditText editor)
    {
        this.editor = editor;
    }

    @Override
    public void onTextChanged(CharSequence arg0, int arg1, int arg2, int arg3)
    {
        // check the text, and if the user entered 
        // something wrong, change your edittext
        if(something wrong)
        {
            editor.setBackgroundColor(Color.RED); //for example
        }
    }

    @Override
    public void afterTextChanged(Editable arg0){}

    @Override
    public void beforeTextChanged(CharSequence arg0, int arg1, int arg2, int arg3){}


}

And then you can use it on all your EditTexts like

EditText editor = (EditText) findViewById(...your id...);
editor.addTextChangedListener(new TextCheck(editor));