String Math Expression Calculator

Use UI Component:

import com.programmisty.calc.*;

public class Sample1 {
    public static void main(String a[]) throws Exception {
       // Change UI Look And Feel (If needed)  //UIManager.setLookAndFeel("com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel");
        JFrame frame = new JFrame("Simple Calculator");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        // Important! ADD CALCULATOR PANEL
        frame.getContentPane().add(new CalculatorPanel());
        frame.pack();
        frame.setVisible(true);
    }
}

Use API :

import com.programmisty.calc.*;
import java.math.BigDecimal;
public class Sample2 {
    public static void main(String args[]) throws Exception {
           BigDecimal a = Calc.eval("100+100/5");
           double x = Calc.deval("100+100/4");
           int y = Calc.ieval("100+100/4");
    }
}