Hi I just started to use java from using other programming languages and decided to convert one of my old projects' it a Reverse Polish notation class to do calculations very basic but works hope you find it useful comments welcome.

jrpn class

Code:
import java.util.Stack;

public class jrpn {
    private double m_result;

    private double max(double value1, double value2){
        if(value1 > value2){
            return value1;
        }
        else{
            return value2;
        }
    }
    private double min(double value1, double value2){
        if(value1 < value2){
            return value1;
        }
        else{
            return value2;
        }
    }

    private Boolean isNum(String value){
        try {
            double N;
            N = Double.parseDouble(value);
            return true;
        }catch (NumberFormatException E){
            return false;
        }
    }

    private boolean isOperator(String value){
        return value.equals("+") || value.equals("-")
                || value.equals("*") || value.equals("/")
                || value.equals("%");
    }

    public jrpn(String expression){
        this.m_result = 0.0;
        Stack<Double>stack = new Stack<>();
        String[]tokens = expression.split(" ");
        String S0;
        Double A;
        Double B;

        label:
        for (String S : tokens) {
            S0 = S.trim().toUpperCase();
            if (S0.length() > 0) {
                if (isNum(S0)) {
                    //Push numbers onto stack.
                    stack.push(Double.parseDouble(S));
                } else {
                    if (isOperator(S0)) {
                        A = stack.pop();
                        B = stack.pop();

                        switch (S0) {
                            case "+":
                                stack.push(B + A);
                                break;
                            case "*":
                                stack.push(B * A);
                                break;
                            case "-":
                                stack.push(B - A);
                                break;
                            case "/":
                                if (A == 0) {
                                    System.out.println("Division by zero.");
                                    stack.push(0.0);
                                    break label;
                                } else {
                                    stack.push(B / A);
                                }
                                break;
                            case "%":
                                stack.push(B % A);
                                break;
                            default:
                                stack.push(0.0);
                                break;
                        }
                    }
                    else{
                        A = stack.pop();

                        switch (S0){
                            case "SIN":
                                stack.push(Math.sin(A));
                                break;
                            case "COS":
                                stack.push(Math.cos(A));
                                break;
                            case "LOG":
                                stack.push(Math.log(A));
                            case "SQR":
                                stack.push((A * A));
                                break;
                            case "EXP":
                                stack.push(Math.exp(A));
                                break;
                            case "MIN":
                                B = stack.pop();
                                stack.push(min(A,B));
                                break;
                            case "MAX":
                                B = stack.pop();
                                stack.push(max(A,B));
                                break;
                        }
                    }
                }
            }
        }
        this.m_result = stack.pop();
    }
    
    public double getResult(){
        return this.m_result;
    }
}
Main example using the class.



Code:
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        String exp;

        System.out.print("Enter Expression : ");
        Scanner scan = new Scanner(System.in);
        exp = scan.nextLine();

        jrpn rpn = new jrpn(exp);
        System.out.print(rpn.getResult());
        scan.close();
    }
}