前置き

今回作る電卓は前回作った初心者向けのアップグレード版みたいなものです。
初心者向けの方を作りたい方は以下のリンクから飛んでください。
https://qiita.com/Puroguramingu_Bennkyoutyuu/items/5a6f93a53ba7fffb110f
サンプルコード

電卓.java
//インポート
import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.TextField;
import javafx.scene.layout.GridPane;
import javafx.stage.Stage;
import java.util.Stack;

public class AdvancedCalculator extends Application {
    private TextField display;
    private StringBuilder input;

    @Override
    public void start(Stage primaryStage) {
        primaryStage.setTitle("Advanced Calculator");

        input = new StringBuilder();
        display = new TextField();
        display.setEditable(false);

        GridPane grid = new GridPane();
        grid.setPadding(new Insets(10, 10, 10, 10));
        grid.setVgap(8);
        grid.setHgap(8);

//ボタン配置
        String[][] buttonLabels = {
                {"7", "8", "9", "/"},
                {"4", "5", "6", "*"},
                {"1", "2", "3", "-"},
                {"0", ".", "=", "+"},
                {"sqrt", "C", "^", "("},
                {")", "sin", "cos", "tan"},
                {"log", "exp", "!", "π"}
        };

        for (int row = 0; row < buttonLabels.length; row++) {
            for (int col = 0; col < buttonLabels[row].length; col++) {
                Button button = new Button(buttonLabels[row][col]);
                button.setMinSize(50, 50);
                button.setOnAction(e -> buttonClicked(button.getText()));
                grid.add(button, col, row);
            }
        }

        grid.add(display, 0, 7, 4, 1);

        Scene scene = new Scene(grid, 250, 400);
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    private void buttonClicked(String buttonText) {
        switch (buttonText) {
            case "=":
                try {
                    double result = evaluateExpression(input.toString());
                    display.setText(Double.toString(result));
                    input.setLength(0);
                    input.append(result);
                } catch (Exception e) {
                    display.setText("Error");
                    input.setLength(0);
                }
                break;
            case "C":
                input.setLength(0);
                display.clear();
                break;
            default:
                input.append(buttonText);
                display.appendText(buttonText);
        }
    }

    private double evaluateExpression(String expression) {
        String[] tokens = expression.split("(?<=op)|(?=op)".replace("op", "[-+*/^()]"));
        Stack<Double> values = new Stack<>();
        Stack<String> operators = new Stack<>();

        for (String token : tokens) {
            if (token.matches("-?\\d+(\\.\\d+)?")) {
                values.push(Double.parseDouble(token));
            } else if (token.matches("[+\\-*/^()]")) {
                while (!operators.isEmpty() && hasPrecedence(token, operators.peek())) {
                    applyOperator(values, operators.pop());
                }
                operators.push(token);
            }
        }

        while (!operators.isEmpty()) {
            applyOperator(values, operators.pop());
        }

        return values.pop();
    }

    private boolean hasPrecedence(String op1, String op2) {
        return getPrecedence(op1) <= getPrecedence(op2);
    }

    private int getPrecedence(String operator) {
        switch (operator) {
            case "+":
            case "-":
                return 1;
            case "*":
            case "/":
                return 2;
            case "^":
                return 3;
            default:
                return 0;
        }
    }

    private void applyOperator(Stack<Double> values, String operator) {
        if (operator.equals("(") || operator.equals(")")) {
            return;
        }

        double operand2 = values.pop();
        double operand1 = values.pop();

        switch (operator) {
            case "+":
                values.push(operand1 + operand2);
                break;
            case "-":
                values.push(operand1 - operand2);
                break;
            case "*":
                values.push(operand1 * operand2);
                break;
            case "/":
                values.push(operand1 / operand2);
                break;
            case "^":
                values.push(Math.pow(operand1, operand2));
                break;
            default:
                break;
        }
    }

    public static void main(String[] args) {
        launch(args);
    }
}
コードはこんな感じです。
なんか間違ってたらコメントしてください。
以上です。