Tweak to the "Sup" Java FX App

Question

Hi all,
So I made a little tweak to the JavaFX app.  Just a simple if statement that attempts to force the user to add something to the text field.  Only no matter what I try, i always get the same (succesful) message that would come if something was typed.
Here's my code, any ideas?  Thanks  :)
```java
package sample;
import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Group;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.TextField;
import javafx.scene.layout.VBox;
import javafx.scene.text.Text;
import javafx.stage.Stage;
public class Main extends Application {
@Override
public void start(Stage primaryStage) throws Exception{
    //Parent root = FXMLLoader.load(getClass().getResource("sample.fxml"));
    Group root = new Group();

//Set up new child nodes
    Text txt = new Text("Hello I'm a JavaFX Text node");
    TextField userName = new TextField();
    VBox box = new VBox();
    Button btn = new Button();

//run methods on nodes
    btn.setText("Click Me!");
    if(userName.getText() == " ") {
        btn.setOnAction(evt -> System.out.printf("Error: You need to enter something in this box for this program to work"));
    } else {
        btn.setOnAction(evt -> System.out.printf("Good job, %s.  Sup was clicked%n", userName.getText()));

}
    root.getChildren().add(box);
    box.getChildren().addAll(txt, userName, btn);   //new layout
    txt.setY(50);  //place text node.

primaryStage.setTitle("Whaddup, Java");
    primaryStage.setScene(new Scene(root, 300, 275));
    primaryStage.show();
}

public static void main(String[] args) {
    launch(args);
}
}
```

Brendon Butler · Accepted Answer

From the looks of things, you have a space character inside this if statement
java
if(userName.getText() == " ");

this means that the user would have to type the space character into the TextField. If you changed that, your code might work, but it might not as well. 
Whenever comparing Strings you should use ".equals()" or ".equalsIgnoreCase()" instead of "==". I don't know the exact reasoning behind it. I know that about half of the time, it could cause an issue.
Your new if statement should look like this
java
if (userName.getText().equals("");

I also took a look at the source code (http://grepcode.com/file/repo1.maven.org/maven2/net.java.openjfx.backport/openjfx-78-backport/1.8.0-ea-b96.1/javafx/scene/control/TextInputControl.java) for the getText() method. And it looks like it is possible to return null.
So another possible if statement could be
java
if (userName.getText() == null);

EDIT:
If you want to include the space character in your check, (so people can't have a space as their name) use this
java
if (userName.getText().trim().equals(""));

Hopefully this helps. Happy coding! :)

Boban Talevski · Answer

Is it really working though? Tried to do the same thing, but it seems that if check is done only once when the application starts and at the time the text field is empty, so the button action is set according to the empty text field and there's no way to change it. Even if you write something inside the text field, the action is already set when the app was initialized, a button click isn't going to change the action, it will always print whatever you set it out to print if the name field was empty.
The if check probably needs to be done inside the button action. We need to use the longer lambda form, i.e., not a one liner. Also, this condition seems to work for both an empty field and one or more spaces, which is just a basic check for something entered in the field. This is what I'm talking about.
java
btn.setOnAction(event -> {
            if ((nameFld.getText() + " ").trim().equals("")){
                System.out.println("Error: You need to enter something in this box for this program to work");
            } else {
                System.out.printf("Sup %s! %n", nameFld.getText());
            }
        });

Welcome to the Treehouse Community

Looking to learn something new?

Jonathan Grieve

Jonathan Grieve

Tweak to the "Sup" Java FX App

2 Answers

Brendon Butler

Brendon Butler

Jonathan Grieve

Jonathan Grieve

Boban Talevski

Boban Talevski

<noob />

<noob />

Brendon Butler

Brendon Butler

Boban Talevski

Boban Talevski