I dont want to save the field with null values in MongoDB using Morphia

I have a form with many fields, I want to save this fields in mongodb in a collection. I want if the user doesnt fill a textfield, then this field should not be saved in the collection.

I have an District Entity. This entity contains another two entities (contact and address).

The District class lokks like this:

public class District {
    @Id private ObjectId id;
    private String Type;
    private String Name;
    private Contact contact;
    private  Address address;

    /**
     * @return the Type
     */
    public String getType() {
        return Type;
        }
....

    /**
     * @param Type the Type to set
     */
    public void setType(String Type) {
        this.Type = Type;
    }

For contact I have this Java class:

@Embedded
public class Contact {
    private String email;
    private String fax;
    private String firstname;
    private String lastname;
    private String gender;
    private String telephone;
    private String title; 

    /**
     * @return the email
     */
    public String getEmail() {
        return email;
    }

    /**
     * @param email the email to set
     */
    public void setEmail(String email) {
        this.email = email;
    }

    /**
     * @return the fax
     */
    public String getFax() {
        return fax;
    }

    /**
     * @param fax the fax to set
     */
    public void setFax(String fax) {
        this.fax = fax;
    } 
...

and my form lokks like this:

private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {                                         
       Mongo mongo = null;
        try {
            mongo = new Mongo();
        } catch (UnknownHostException ex) {
            Logger.getLogger(TestForm.class.getName()).log(Level.SEVERE, null, ex);
        }
        Morphia morphia=new Morphia();
        morphia.map(District).map(Contact).map(Address);


      District district=new District();


      district.setName(jTextField2.getText());
      district.setType(jTextField3.getText());

      Address address=new Address();
      address.setCity(jTextField11.getText());
      address.setStreet(jTextField10.getText());
      address.setZipcode(jTextField9.getText());
....
 Datastore ds=morphia.createDatastore(mongo, "rcfdb");
      ds.save(district);

I want if the user doesnt fill the Name field in the Form, then this field is not written in the MongoDB.(now I see the field i.e Name with null value) I have tried to do that but that didnt help me:

....
if(jTextField4.getText()!="")
       {
         contact.setName(jTextField4.getText());
       }
....

could you please help me to do this job?

thanks

Use String#equals to compare String content. The == operator compares object references. JTextField#getText returns a different String object compared to the interned one "" being compared so the field value for the Entity contact is never set.

if (jTextField4.getText().equals("")) {
   contact.setName(jTextField4.getText());
}