How to clear textfield value

I want to clear textfield value dynamically

textField.setValue("")

we have done this but it not working it throws “NULL POINTER EXCEPTION” and below is our code

package com.company.sample.web.customer;

import com.haulmont.cuba.core.global.Metadata;
import com.haulmont.cuba.gui.components.AbstractEditor;
import com.company.sample.entity.Customer;
import com.haulmont.cuba.gui.components.FieldGroup;
import com.haulmont.cuba.gui.components.LookupField;
import com.haulmont.cuba.gui.components.TextField;
import com.haulmont.cuba.gui.data.Datasource;
import com.haulmont.cuba.gui.xml.layout.ComponentsFactory;

import javax.inject.Inject;
import javax.inject.Named;
import java.util.Map;

public class CustomerEdit extends AbstractEditor<Customer> {

           @Named("fieldGroup.age")
           private TextField age;



    @Override
    public void init(Map<String, Object> params) {
     

        age.addTextChangeListener(event -> {
           if(event.getText().matches("[A-Za-z]+")) {
               System.out.println("CHECKING...............................");
               age.setValue("");
              // showNotification(event.getText(),NotificationType.HUMANIZED);
           }


        });
    }
}

Is there a reason you don’t have age as an integer in the entity? If you do, CUBA will stop you putting non-numeric characters in the field by default.

It can be null, and you should check it first.

We have checked that but it is not working