JFXComboBox does not show default set value - javafx

Question

I am using a JFXComboBox to show user group a user can be allocated to. The roles are fetched from the DB. Fetching of the rolelist is done by getRoleNameList(). I populate the JFXComboBox as below:
Populate userGroup JFXComboBox
// Populate userGroup JFXComboBox
ObservableList<Role> roles = rdc.getRoleNameList();
roles.sort(Comparator.comparing(Role::getCode)); // Sort the list
uGroupComboBox.getItems().setAll(roles);
uGroupComboBox.setVisibleRowCount(5);
JFXCombobox FXML:
<JFXComboBox id="userGroup" fx:id="uGroupComboBox" focusColor="#07595a"
layoutX="245.0" layoutY="256.0" prefHeight="30.0" prefWidth="148.0"
promptText="Select User Group" styleClass="jfx-combo-box"
unFocusColor="#48aaad">
The model below is for Roles:
package records.models;
import javafx.beans.property.SimpleStringProperty;
import javafx.beans.property.StringProperty;
import org.apache.commons.lang3.StringUtils;
public class Role {
private final StringProperty code;
private final StringProperty name;
public Role() {
this.name = new SimpleStringProperty();
this.code = new SimpleStringProperty();
}
public Role(String name) {
String codename = StringUtils.capitalize(name.toLowerCase().trim());
this.code = new SimpleStringProperty(codename);
name = name.toLowerCase().trim();
this.name = new SimpleStringProperty(name);
}
// name
public String getName() {
return name.get();
}
public void setName(String name) {
if (name != null) {
name = name.toLowerCase().trim();
}
this.name.set(name);
}
public StringProperty nameProperty() {
return name;
}
// #return code
public String getCode() {
return code.get();
}
public void setCode(String code) {
if (code != null) {
code = StringUtils.capitalize(code.toLowerCase().trim());
}
this.code.set(code);
}
public StringProperty codeProperty() {
return code;
}
public Role getRole(){
return this;
}
#Override
public String toString(){
return this.code.get();
}
}
When I fetch from the DB the user group the user is assigned to, the data is not displayed:
String uRole = role.get("role") == null ? null :
role.get("role").toString();
user.setRole(uRole);
// Create the role that is fetched from DB
Role uGroup = new Role(uRole);
// uGroupComboBox.setValue(uGroup);
uGroupComboBox.getSelectionModel().select(uGroup);
This does not work. As you can see, the field is not null. If it were, I would show the prompt text
However, the JFXComboBox list is successfully populated:
If I do System.out.println(uGroupComboBox.getValue()); it shows the correct value eg. if the user group is Nurse, the statement returns Nurse
Why does the JFXComboBox not display the value?

Answer 1

The problem is in your Role object with its StringProperty properties. Let me explain myself.
if you just take :
static void main(String[] args){
StringProperty codeName = new SimpleStringProperty("codename");
StringProperty codeNameSameValue = new SimpleStringProperty("codename");
boolean isthesame = codeName.equals(codeNameSameValue);
System.out.println("isthesame:"+isthesame);
boolean isReallyTheSame = codeName.get().equals(codeNameSameValue.get());
System.out.println("isReallyTheSame:"+isReallyTheSame);
}
You will see on you console output
isthesame:false
isReallyTheSame:true
Ok it is still not the answer to your question but for you Role class default equals method that will be comparing object properties like my first comparison:
comparingStringProperty.equals(comparedStringProperty);
...
To solve the problem you need to override the equals method in the Role object. For example with something like that:
i
mport java.util.Objects;
import javafx.beans.property.SimpleStringProperty;
import javafx.beans.property.StringProperty;
import org.apache.commons.lang3.StringUtils;
public class Role {
private final StringProperty code;
private final StringProperty name;
/*Constructors, setters and getter are deleted for clarity */
....
#Override
public String toString() {
return this.code.get();
}
#Override
public boolean equals(Object o) {
// If the object is compared with itself then return true
if (o == this) {
return true;
}
/* Check if o is an instance of Role or not
"null instanceof [type]" also returns false */
if (!(o instanceof Role)) {
return false;
}
// typecast o to Role so that we can compare data members
Role r = (Role) o;
return (r.name.get() == this.name.get() || r.name.get() != null && r.name.get().equals(this.name.get()));
}
#Override
public int hashCode() {
return Objects.hash(name.get(), code.get());
}
}
This equals method will be use during the call :
uGroupComboBox.getSelectionModel().select(uGroup);
And voila!