Question

Java:

In this assignment, you will create an accumulator accumulator-calculator that displays a sad face “ :-( “ whenever the number displayed by the calculator is negative and a happy face “ :-) ” whenever the number displayed is positive.
The calculator responds to the following commands: num + , num - , num * , num / and C ( Clear ).

After initial run, if the user clicks 8 and then presses the “+” button for example, the accumulator value displays 8 in one field and a happy face in the other. If the second number entered by the user is 9 followed by “-“ button, the accumulator displays -1 and the face changes to the sad mode. If the next command is C, the accumulator will be initialized back to zero and the two Text Fields will be cleared

Notice also that, this kind of calculator accepts only single digit numbers as input at any given time. (i.e. Single digit number followed by an operation).

import javax.swing.JOptionPane;
import javafx.application.Application;
import javafx.stage.Stage;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.TextField;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.GridPane;
import javafx.scene.layout.HBox;

public class StartupAccumulatorCalculator_JavaFX extends Application {

private TextField txtOutput = new TextField();
TextField txtFace = new TextField();

private float inputValue;

private Calculator calculator = new Calculator();
private Face face = new Face();

public static void main(String[] args) {
launch(args);
}
@Override // Override the start method in the Application class
public void start(Stage primaryStage) {
// Create a scene by calling the getPane() method and place it in the stage
Scene scene = new Scene(getPane(), 200, 250);
primaryStage.setTitle("Fun Calculator"); // Set the stage title
primaryStage.setScene(scene); // Place the scene in the stage
primaryStage.show(); // Display the stage
}

/**
* getPane() returns a pane to be used with the scene of this calculator.
* In this method, you will need to generate the GUI of this calculator. Use different kinds of panes for alignment
* This method will also implement the event handlers for each button press. You may elect to divide the load among multiple methods if you prefer.
*/
protected BorderPane getPane() {

   BorderPane mainPane = new BorderPane();
   //Your code goes here .....
  
  
  
  
  
  
  
  
  
  
  
  
return mainPane;
}
//----------------------------------------------------------
/**
* This method checks the accumulator value and by calling getAccumValue(). based on this value it either calls the
* face.makeHappy() or face.makeSad() and sets the face to happy/sad in txtFace
* Will be called whenever one of the operation buttons is pressed
*/
public void display(){

   //Your code goes here .....
     
     
     
     
     
     
   }
}
//*********************************************************
class Calculator
{
private float currentAccumValue;
public Calculator (){
       currentAccumValue = 0.0f;
}

public void add(float inputValue){
currentAccumValue+= inputValue;
}

public void subtract(float inputValue){
currentAccumValue-= inputValue;
}

public void multiply(float inputValue){
currentAccumValue*= inputValue;
}

public void divide(float inputValue){
   if(inputValue == 0) {
JOptionPane.showMessageDialog(null, "Error: You cannot divide by 0!", "Error",
JOptionPane.INFORMATION_MESSAGE);
   } else {
   currentAccumValue /= inputValue;
   }
}

public void clearAccum(){
currentAccumValue = 0;
}
public float getAccumValue(){
return currentAccumValue;
}
}
//*********************************************************

class Face
{
private boolean faceState;

public Face(){
   makeHappy();
}

public void makeHappy(){
faceState = true;
}

public void makeSad(){
faceState = false;
}

public boolean getFaceState(){
return faceState;

}
}

Answer 1

Here is the completed code for this problem. Comments are included, go through it, learn how things work and let me know if you have any doubts or if you need anything to change. If you are satisfied with the solution, please rate the answer. Thanks

// StartupAccumulatorCalculator_JavaFX.java

import javax.swing.JOptionPane;

import javafx.application.Application;

import javafx.geometry.Insets;

import javafx.stage.Stage;

import javafx.scene.Scene;

import javafx.scene.control.Button;

import javafx.scene.control.TextField;

import javafx.geometry.Pos;

import javafx.scene.control.Label;

import javafx.scene.layout.BorderPane;

import javafx.scene.layout.GridPane;

import javafx.scene.layout.HBox;

public class StartupAccumulatorCalculator_JavaFX extends Application {

    private TextField txtOutput = new TextField();

    TextField txtFace = new TextField();

    private float inputValue;

    private Calculator calculator = new Calculator();

    private Face face = new Face();

    public static void main(String[] args) {

       launch(args);

    }

    @Override // Override the start method in the Application class

    public void start(Stage primaryStage) {

        // Create a scene by calling the getPane() method and place it in the stage

        Scene scene = new Scene(getPane(),300,300);

        primaryStage.setTitle("Fun Calculator"); // Set the stage title

        primaryStage.setScene(scene); // Place the scene in the stage

        primaryStage.show(); // Display the stage

    }

    /**

     * getPane() returns a pane to be used with the scene of this calculator. In

     * this method, you will need to generate the GUI of this calculator. Use

     * different kinds of panes for alignment This method will also implement

     * the event handlers for each button press. You may elect to divide the

     * load among multiple methods if you prefer.

     */

    protected BorderPane getPane() {

        BorderPane mainPane = new BorderPane();

        //setting some padding

        mainPane.setPadding(new Insets(20));

        //creating an HBox to include output text and face text

        HBox hbox = new HBox(txtOutput, txtFace);

        hbox.setSpacing(10);

        //aligning center

        hbox.setAlignment(Pos.CENTER);

        //creating a 2D array containing the value needs to be displayed on buttons

        //in that order

        Object buttons[][] = new Object[][]{{7, 8, 9, "/"}, {4, 5, 6, "*"}, {1, 2, 3, "-"}, {null, 0, "C", "+"}};

        //creating a grid for the buttons, adjusting attributes

        GridPane buttonsPane = new GridPane();

        buttonsPane.setHgap(10);

        buttonsPane.setVgap(10);

        buttonsPane.setAlignment(Pos.CENTER);

        buttonsPane.setPadding(new Insets(20));

        //looping for each row and column

        for (int i = 0; i < 4; i++) {

            for (int j = 0; j < 4; j++) {

                //adding a Button to grid pane if element at i, j in buttons array

                //is not null, else a dummy label node

                if (buttons[i][j] != null) {

                    Button b = new Button(buttons[i][j].toString());

                    //adding action listener to call handleClick method,

                    //passing the text of button as argument

                    b.setOnAction(e -> handleClick(b.getText()));

                    //adding to grid at column j and row i

                    buttonsPane.add(b, j, i);

                } else {

                    //dummy node, just to fill vacant space

                    buttonsPane.add(new Label(""), j, i);

                }

            }

        }

       

        //adding hbox to top and buttons to center

        mainPane.setTop(hbox);

        mainPane.setCenter(buttonsPane);

        //Your code goes here .....

        return mainPane;

    }

//----------------------------------------------------------

    /**

     * This method checks the accumulator value and by calling getAccumValue().

     * based on this value it either calls the face.makeHappy() or

     * face.makeSad() and sets the face to happy/sad in txtFace Will be called

     * whenever one of the operation buttons is pressed

     */

    public void display() {

        if (calculator.getAccumValue() >= 0) {

            //happy

            face.makeHappy();

        } else {

            //sad

            face.makeSad();

        }

        if (face.getFaceState()) {

            //setting happy face

            txtFace.setText(":-)");

        } else {

            //setting sad face

            txtFace.setText(":-(");

        }

    }

   

    //event handler for button clicks

    private void handleClick(String str) {

        //getting the character on the label of clicked button

        char c = str.toUpperCase().charAt(0);

        //if it is a digit, parsing digit and assigning to inputValue

        if (Character.isDigit(c)) {

            inputValue = Character.digit(c, 10);

        } else {

            //if it is an operator, finding and performing the selected operation

          switch (c) {

                case '/':

                    //division

                    calculator.divide(inputValue);

                    txtOutput.setText("" + calculator.getAccumValue());

                    display();

                    break;

                case '+':

                    //addition

                    calculator.add(inputValue);

                    txtOutput.setText("" + calculator.getAccumValue());

                    display();

                    break;

                case '-':

                    //subtraction

                    calculator.subtract(inputValue);

                    txtOutput.setText("" + calculator.getAccumValue());

                    display();

                    break;

                case '*':

                    //multiplication

                    calculator.multiply(inputValue);

                    txtOutput.setText("" + calculator.getAccumValue());

                    display();

                    break;

                case 'C':

                    //reset/clear

                    calculator.clearAccum();

                    txtFace.setText("");

                    txtOutput.setText("");

                    break;

            }

        }

    }

}

//*********************************************************

class Calculator {

    private float currentAccumValue;

    public Calculator() {

        currentAccumValue = 0.0f;

    }

    public void add(float inputValue) {

        currentAccumValue += inputValue;

    }

    public void subtract(float inputValue) {

        currentAccumValue -= inputValue;

    }

    public void multiply(float inputValue) {

        currentAccumValue *= inputValue;

    }

    public void divide(float inputValue) {

        if (inputValue == 0) {

            JOptionPane.showMessageDialog(null, "Error: You cannot divide by 0!", "Error",

                    JOptionPane.INFORMATION_MESSAGE);

        } else {

            currentAccumValue /= inputValue;

        }

    }

    public void clearAccum() {

        currentAccumValue = 0;

    }

    public float getAccumValue() {

        return currentAccumValue;

    }

}

//*********************************************************

class Face {

    private boolean faceState;

    public Face() {

        makeHappy();

    }

    public void makeHappy() {

        faceState = true;

    }

    public void makeSad() {

        faceState = false;

    }

    public boolean getFaceState() {

        return faceState;

    }

}

/*OUTPUT*/