How to check if a tab is already opened in TabPane in JavaFX

Question

I'm adding tabs dynamically from fxml files by clicking a button. Is there a way to check to see if that tab is already opened in TabPane in JavaFX and switch to that Tab instead of adding the same Tab to TabPane.

Here is my controller class:-

    package application;

import java.io.IOException;
import java.net.URL;
import java.util.ResourceBundle;

import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.fxml.Initializable;
import javafx.scene.control.Button;
import javafx.scene.control.Tab;
import javafx.scene.control.TabPane;
import javafx.scene.layout.AnchorPane;

public class MainController implements Initializable{

    @FXML
    public TabPane myTabPane ;
    public AnchorPane myAnchorPane;

    @FXML
    public Button btnTab1 = new Button();
    @FXML
    public Button btnTab2 = new Button();
    @FXML
    public Button btnTab3 = new Button();

    @Override
    public void initialize(URL location, ResourceBundle resources) {

        btnTab1.setOnAction(e -> {
            //System.out.println("Clicked");            
            try {
                Tab myNewTab = FXMLLoader.load(this.getClass().getResource("MyTestTab.fxml"));
                myTabPane.getTabs().add(myNewTab);
            } catch (IOException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            }
        });

        btnTab2.setOnAction(e -> {
            try {               
                Tab myNewTab = FXMLLoader.load(this.getClass().getResource("MyTestTab2.fxml"));
                myTabPane.getTabs().add(myNewTab);
            } catch (IOException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            }           
        });
    }
}

Here is my Main FXML File:-

    <?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.control.Button?>
<?import javafx.scene.control.SplitPane?>
<?import javafx.scene.control.TabPane?>
<?import javafx.scene.control.ToolBar?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.layout.BorderPane?>

<BorderPane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/8.0.60" xmlns:fx="http://javafx.com/fxml/1" fx:controller="application.MainController">
   <top>
      <ToolBar prefHeight="40.0" prefWidth="200.0" BorderPane.alignment="CENTER">
        <items>
          <Button fx:id="btnTab1" mnemonicParsing="false" text="Tab1" />
            <Button fx:id="btnTab2" mnemonicParsing="false" text="Tab2" />
            <Button fx:id="btnTab3" mnemonicParsing="false" text="Tab3" />
        </items>
      </ToolBar>
   </top>
   <center>
      <SplitPane dividerPositions="0.29797979797979796" prefHeight="160.0" prefWidth="200.0" BorderPane.alignment="CENTER">
        <items>
          <AnchorPane fx:id="myTabAnchPane" minHeight="0.0" minWidth="0.0" prefHeight="160.0" prefWidth="100.0">
               <children>
                  <TabPane fx:id="myTabPane" layoutX="-12.0" layoutY="34.0" prefHeight="358.0" prefWidth="175.0" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="0.0" />
               </children></AnchorPane>
          <AnchorPane fx:id="myAnchorPane" minHeight="0.0" minWidth="0.0" prefHeight="160.0" prefWidth="100.0" />
        </items>
      </SplitPane>
   </center>
</BorderPane>

And here is my FXML File for one of the Tab (Tab2):-

    <?xml version="1.0" encoding="UTF-8"?>

<?import javafx.geometry.Insets?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.control.Tab?>
<?import javafx.scene.control.TextArea?>
<?import javafx.scene.control.TextField?>
<?import javafx.scene.layout.HBox?>
<?import javafx.scene.layout.Pane?>
<?import javafx.scene.layout.VBox?>

<Tab fx:id="tab2" text="My Profile" xmlns="http://javafx.com/javafx/8.0.60" xmlns:fx="http://javafx.com/fxml/1">
         <content>
            <VBox prefHeight="200.0" prefWidth="100.0">
               <children>
                  <HBox spacing="10.0">
                     <children>
                        <Label text="Bank Statement File" />
                        <TextField prefHeight="25.0" prefWidth="288.0" />
                        <Button mnemonicParsing="false" text="Browse" />
                     </children>
                     <VBox.margin>
                        <Insets left="20.0" top="20.0" />
                     </VBox.margin>
                  </HBox>
                  <HBox VBox.vgrow="ALWAYS">
                     <children>
                        <Pane prefHeight="200.0" prefWidth="135.0" />
                        <TextArea HBox.hgrow="ALWAYS" />
                        <Pane prefHeight="200.0" prefWidth="200.0" />
                     </children>
                     <padding>
                        <Insets top="50.0" />
                     </padding>
                  </HBox>
                  <Pane prefHeight="64.0" prefWidth="600.0" />
               </children>
            </VBox>
         </content></Tab>

Answer 1

Just have the controller track which FXML files you have opened (I refactored the code slightly to get rid of all the repetition).

As an aside, never, ever initialize @FXML-annotated fields. I.e. never do @FXML private Button btnTab1 = new Button();.

package application;

import java.io.IOException;
import java.net.URL;
import java.util.Map ;
import java.util.HashMap ;
import java.util.ResourceBundle;

import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.fxml.Initializable;
import javafx.scene.control.Button;
import javafx.scene.control.Tab;
import javafx.scene.control.TabPane;
import javafx.scene.layout.AnchorPane;

public class MainController implements Initializable{

    private Map<String, Tab> openTabs = new HashMap<>();

    @FXML
    private TabPane myTabPane ;
    @FXML
    private AnchorPane myAnchorPane;

    @FXML
    private Button btnTab1 ;
    @FXML
    private Button btnTab2 ;
    @FXML
    private Button btnTab3 ;

    @Override
    public void initialize(URL location, ResourceBundle resources) {
        btnTab1.setOnAction(e -> openTab("MyTestTab.fxml"));
        btnTab2.setOnAction(e -> openTab("MyTestTab2.fxml"));
    }

    private void openTab(String fxmlFile) {
        if (openTabs.containsKey(fxmlFile)) {
            myTabPane.getSelectionModel().select(openTabs.get(fxmlFile));
        } else {
            try {               
                Tab myNewTab = FXMLLoader.load(this.getClass().getResource(fxmlFile));
                myTabPane.getTabs().add(myNewTab);
                openTabs.put(fxmlFile, myNewTab);
                myNewTab.setOnClosed(e -> openTabs.remove(fxmlFile));
            } catch (IOException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            }           
        }
    }
}