Java Cart Phone java

package cart;

import cart.utils.ValidationUtils;

//Phone - has methods to store phone numbers
//author - Lawrence Truett - FluffyCat.com
//date - August 12, 2003 - San Diego, CA
public class Phone {
    private String rawPhone = null;
    private String errorString = null;
    
    public Phone() {}
    
    public Phone(String phoneIn) {
        this.setPhone(phoneIn);
    }
    
    public static String getElement() {
        return "Phone Number";
    }
    
    //for now just store raw phone number as passed in
    public String getPhone() {return rawPhone;}
    private void setPhone(String phoneIn) {
        this.rawPhone = phoneIn;
    }
    
    private String getErrorString() {return errorString;}
    private void setErrorString(String errorStringIn) {
        this.errorString = errorStringIn;
    }
    
    //very basic phone edits - how should phone be edited?
    public boolean isValid() {
        if (this.getPhone().trim().length() > 7) {
            this.setErrorString("phone must be greter than 7 digits");
            return true;
        } else {
            return false;
        }
    }
    //method used for data input
    public boolean isValidOrNull() {
        if ((ValidationUtils.isStringBlank(this.getPhone()))) {
            return true;
        } else {
            return this.isValid();
        }
    }
    public String getErrorMessage() {
        if (this.isValid()) {
            return " ";
        } else {
            return this.getErrorString();
        }
    }
    
    public String getErrorOrNullMessage() {
        if  (ValidationUtils.isStringBlank(this.getPhone())) {
            return "Phone Number Is Blank";
        } else {
            return this.getErrorMessage();
        }
    }
    
    public String toString() {return ("phone: " + this.getPhone());}
}