Materialize class="validate" property is not validating field in React

Question

I am creating Materialize Form with React js, to ensure fields are not empty I am using materialize class="validate" property. Even I used required="" and aria-required="true" but while clicking on Submit button empty fields are not getting validate. I dont know why.

Please help me on this..

class ContactForm extends Component {

 render() {

 return (
 <div>
 <form onSubmit={this.handleSubmit}>

      <div className="input-field col s12 l10">
             <i className="material-icons prefix">text_format</i>
             <input type="text" id="name" ref="Name" class="validate" required="" aria-required="true"></input>
             <label htmlFor="name">Your Name</label>
      </div>

      <div className="input-field col s12 l10">
               <i className="material-icons prefix">phone</i>
               <input type="number" id="phone" ref="MobileNo" class="validate" required="" aria-required="true"></input>
               <label htmlFor="phone">Mobile No.</label>
       </div>

      <div className="input-field col s12 l10">
                <i className="material-icons prefix">email</i>
                <input type="email" id="email" ref="EmailId" class="validate" required="" aria-required="true"></input>
                <label htmlFor="email">Your Email</label>
       </div>

       <div className="center">
                <button className="btn" type="submit" >Submit</button>
        </div>

</form>
</div>
);
}
}

export default ContactUsForm;