Question

nToThePowerOfN calculator Enter a positive number (n): Compute n to the power n 3 to the power of 3 27.0

Examine the following code and complete missing parts:

import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;
import javafx.scene.layout.HBox;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

 
public class NtoThePowerOfN extends Application{

    @Override
    public void start(Stage primaryStage) throws Exception {

        TextField inputField; 
        TextField outputField;
        VBox base = new VBox(10);
        
        base.setPadding(new Insets(10));
        base.setAlignment(Pos.CENTER);


        //
        //  A:  input components - label and text field
        //


        //
        //  B:  button - to compute the value
        //

        //
        
        //  C: output components - label and textfield
        //      Make sure the output field cannot be changed by the user

        //


        //  D: event handler for button goes here - try and use a lambda expression
        //


        Scene sc = new Scene(base);
        primaryStage.setScene(sc);
        primaryStage.setTitle("Square root calculator");
        primaryStage.show();
    }

public static void main(String[] args) {

launch(args);

}

}

Answer 1

import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.HPos;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;
import javafx.scene.layout.GridPane;
import javafx.scene.layout.HBox;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class NtoThePowerOfN extends Application {

   @Override
   public void start(Stage primaryStage) throws Exception {

       final TextField inputField = new TextField();
       final TextField outputField = new TextField();
       final Label outputLabel = new Label();
      
       VBox base = new VBox(10);
      
       base.setPadding(new Insets(10));
       base.setAlignment(Pos.CENTER);

       HBox firstRow = new HBox();
       firstRow.getChildren().add(new Label("Enter a positive number(n):\t"));
       firstRow.getChildren().add(inputField);
       firstRow.setAlignment(Pos.CENTER);
      
       base.getChildren().add(firstRow);

       Button computeButton = new Button("Compute n to the power of n");
       base.getChildren().add(computeButton);

       computeButton.setOnAction(new EventHandler<ActionEvent>() {
           @Override
           public void handle(ActionEvent event) {
               try {
                   int n = Integer.parseInt(inputField.getText());
                   outputLabel.setText(n + " to the power of " + n+"\t");
                   outputField.setText(String.valueOf(n * n));
               } catch (NumberFormatException e) {
               }
           }
       });

       HBox secondRow = new HBox();
       secondRow.getChildren().add(outputLabel);
       outputField.setEditable(false);
       secondRow.getChildren().add(outputField);
       secondRow.setAlignment(Pos.CENTER);
      
       base.getChildren().add(secondRow);

       Scene sc = new Scene(base);
       primaryStage.setScene(sc);
       primaryStage.setTitle("Square root calculator");
       primaryStage.show();
   }

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

Square root calculator Enter a positive number(n):6 Compute n to the power of rn 6 to the power of 6 36