CalculatorGUI.java

package Practice;

import javafx.application.Application;
import javafx.event.ActionEvent;
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.stage.Stage;

public class CalculatorGUI extends Application{
    TextField num1,num2;
    Button add,sub,mul,div,clr;
    Label ans;
    @Override
    public void start(Stage primaryStage){
        //Making Controls
        num1=new TextField();
        num2=new TextField();
        add=new Button("+");
        sub=new Button("-");
        mul=new Button("x");
        div=new Button("/");
        clr=new Button("Clear");
        ans=new Label("?");
        ans.setAlignment(Pos.CENTER);
        ans.setStyle("-fx-border-color: #000; -fx-padding: 5px;");
        GridPane root=new GridPane();
        root.setAlignment(Pos.CENTER);
        //Set Spacing between Controls in Grid
        root.setHgap(10);
        root.setVgap(10);
        //adding to Grid
        root.add(add,0,0);
        root.add(sub, 1, 0);
        root.add(mul,0,1);
        root.add(div,1,1);
        root.add(num1,0,2);
        root.add(num2,1,2);
        // 2 Column Buttons
        root.add(ans,0,3,2,1);
        root.add(clr,0,4,2,1);
        setWidths();
        //attach buttons to code in separate method
        attachCode();
        //usual stuff
        Scene scene = new Scene(root, 300, 250);
        primaryStage.setTitle("Calculator");
        primaryStage.setScene(scene);
        primaryStage.show();
    }
    public void setWidths(){
        //set widths of all controls
        num1.setPrefWidth(70);
        num2.setPrefWidth(70);
        add.setPrefWidth(70);
        sub.setPrefWidth(70);
        mul.setPrefWidth(70);
        div.setPrefWidth(70);
        clr.setPrefWidth(150);
        ans.setPrefWidth(150);

    }
    public void attachCode()
    {
        //have each button run BTNCODE when clicked
        add.setOnAction(e -> btncode(e));
        sub.setOnAction(e -> btncode(e));
        mul.setOnAction(e -> btncode(e));
        div.setOnAction(e -> btncode(e));
        clr.setOnAction(e -> btncode(e));
    }
    public void btncode(ActionEvent e)
    {
        int anum1, anum2, answer;
        char symbol;
        //e tells us which button was clicked
        if(e.getSource()==clr)
        {
            num1.setText("");
            num2.setText("");
            ans.setText("?");
            num1.requestFocus();
            return;
        }
        //read numbers in from textfields
        anum1=Integer.parseInt(num1.getText());
        anum2=Integer.parseInt(num2.getText());
        if(e.getSource()==add)
        {
            symbol='+';
            answer=anum1+anum2;

        }
        else if(e.getSource()==sub)
        {
            symbol='-';
            answer=anum1-anum2;
        }
        else if(e.getSource()==mul)
        {
            symbol='x';
            answer=anum1*anum2;
        }
        else
        {
            symbol='/';
            answer=anum1/anum2;
        }
        //display answer
        ans.setText("" + anum1 + symbol + anum2 + "=" + answer);
    }
    public static void main(String[] args) {
        launch(args);

    }


}