Calculator

package com.company;
import java.awt.Color;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextArea;


public class Calculator {


    private JFrame frame = new JFrame("GUI Calculator by Java Coding Community - v.1.0"); // set the title

    private JTextArea txtScreen = new JTextArea(); // this is the screen where the user types numbers from the calc
    private JTextArea outputScreen = new JTextArea(); // this is the screen to present the output / invalid values

    private ImageIcon image = new ImageIcon("src\\javacodingcommunity.png"); // icon in top left




    // creating number buttons;
    // *NOTE: button 1 stands for number 0
    private JButton button1 = new JButton("0");
    private JButton button2 = new JButton("1");
    private JButton button3 = new JButton("2");
    private JButton button4 = new JButton("3");
    private JButton button5 = new JButton("4");
    private JButton button6 = new JButton("5");
    private JButton button7 = new JButton("6");
    private JButton button8 = new JButton("7");
    private JButton button9 = new JButton("8");
    private JButton button10 = new JButton("9");


    // creating operator numbers
    private JButton divideButton = new JButton("/");
    private JButton multiplyButton = new JButton("*");
    private JButton addButton = new JButton("+");
    private JButton substractButton = new JButton("-");
    private JButton powerOf = new JButton("**");
    private JButton root = new JButton("sqrt");
    private JButton clears = new JButton("clr");
    private JButton parenthesis_left = new JButton("(");
    private JButton parenthesis_right = new JButton(")");
    private JButton back = new JButton("←");


    // equals button is more special
    private JButton equals = new JButton("=");



    public Calculator() {
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // default close operation
        frame.setSize(400,550); // calculator size
        frame.setResizable(false); // can't resize it
        frame.setLayout(null); // default layout
        Color customBlue = new Color(133,220,186); // custom colors
        Color customGray = new Color(232,232,232); // custom colors
        frame.getContentPane().setBackground(customBlue);
        // set background


        //editing the txtScreen
        txtScreen.setSize(380,50);
        txtScreen.setLocation(7,5);

        //editing the output screen
        outputScreen.setSize(380,50);
        outputScreen.setLocation(7,70);
        outputScreen.setBackground(customGray);

        // button equals;
        // it is more special than the others :P
        equals.setSize(100,50);
        equals.setLocation(270,450);
        equals.addActionListener(new ActionListener() {
            //this happens when the button is clicked

            @Override
            public void actionPerformed(ActionEvent e) {
                try {
                    // we try to evaluate the text from the text screen
                    // using eval function from Evaluation.java
                    double x = Evaluation.eval(txtScreen.getText());

                    if(x == (1.0/0.0) || x ==(-1.0/0.0) || x == (0.0/0.0)) {
                        // just forbidding the division by 0 as it is Infinity in Java
                        System.out.println("Division by 0 is NOT allowed!");
                        outputScreen.setText("Division by 0 is NOT  allowed.");
                    }
                    else {
                        // if it works then it is printed on the screen
                        outputScreen.setText(Double.toString(x));
                        System.out.println(x);

                    }
                } catch (Exception e1) {
                    // catching any exception
                    // printing it on the screen
                    // and console
                    outputScreen.setText("Invalid Input, Please Try Again!");
                    outputScreen.append("\n"+e1.getMessage());
                    e1.printStackTrace();
                }

            }
        });


        createButtons(); // method that creates buttons

        createActionListeners(); // method that creates  Action Listeners that add numbers

        addObjectsToScreen(); // method that adds objects to screen



        frame.setVisible(true); // this goes after adding elements
        // so it repaints normally


    }

    private void addObjectsToScreen() {

        // function to add all objects to screen
        // it is here to make the code more readable
        frame.add(txtScreen);
        frame.add(outputScreen);
        frame.add(clears);
        frame.add(equals);
        frame.add(button1);
        frame.add(button2);
        frame.add(button3);
        frame.add(button4);
        frame.add(button5);
        frame.add(button6);
        frame.add(button7);
        frame.add(button8);
        frame.add(button9);
        frame.add(button10);
        frame.add(divideButton);
        frame.add(multiplyButton);
        frame.add(addButton);
        frame.add(substractButton);
        frame.add(powerOf);
        frame.add(root);
        frame.add(parenthesis_left);
        frame.add(parenthesis_right);
        frame.add(back);
        frame.setIconImage(image.getImage());

    }

    private void createButtons() {

        // creates buttons
        // it is here to make the program more readable

        //button 1;
        button1.setSize(100,50);
        button1.setLocation(169,299);


        // button 2;
        button2.setSize(100,50);
        button2.setLocation(169,450);


        // button 3;
        button3.setSize(100,50);
        button3.setLocation(69,450);


        // button 4;
        button4.setSize(100,50);
        button4.setLocation(270,399);



        // button 5;
        button5.setSize(100,50);
        button5.setLocation(169,399);



        // button 6;
        button6.setSize(100,50);
        button6.setLocation(69,399);




        // button 7;
        button7.setSize(100,50);
        button7.setLocation(270,349);



        // button 8;
        button8.setSize(100,50);
        button8.setLocation(169,349);



        // button 9;
        button9.setSize(100,50);
        button9.setLocation(69,349);


        //button 10;
        button10.setSize(100,50);
        button10.setLocation(270,299);




        //button clr
        clears.setSize(100,50);
        clears.setLocation(69, 299);

        // button divide
        divideButton.setSize(100,50);;
        divideButton.setLocation(270,220);

        // multiply button
        multiplyButton.setSize(100,50);
        multiplyButton.setLocation(169,220);

        // addition button
        addButton.setSize(100,50);
        addButton.setLocation(69,220);

        // substract button
        substractButton.setSize(100,50);
        substractButton.setLocation(270,170);

        //to the power of
        powerOf.setSize(100,50);
        powerOf.setLocation(169,170);

        // square root button
        root.setSize(100,50);
        root.setLocation(69,170);

        // ( button
        parenthesis_left.setSize(50,50);
        parenthesis_left.setLocation(9,170);

        // ) button
        parenthesis_right.setSize(50,50);
        parenthesis_right.setLocation(9,220);


        // back button
        back.setSize(50,50);
        back.setLocation(9,300);

    }

    private void createActionListeners() {

        // creates action listeners that add text to screen
        // it is here to make the program more readable

        button10.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                txtScreen.append("9");
            }
        });


        button9.addActionListener(new ActionListener() {


            public void actionPerformed(ActionEvent e) {
                txtScreen.append("8");
            }
        });


        button8.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                txtScreen.append("7");
            }
        });


        button7.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                txtScreen.append("6");
            }
        });

        button6.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                txtScreen.append("5");
            }
        });

        button5.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                txtScreen.append("4");
            }
        });


        button4.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                txtScreen.append("3");
            }
        });


        button3.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                txtScreen.append("2");
            }
        });

        button2.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                txtScreen.append("1");
            }
        });

        button1.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                txtScreen.append("0");
            }
        });


        divideButton.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                txtScreen.append("/");
            }
        });


        multiplyButton.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                txtScreen.append("*");
            }
        });


        addButton.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                txtScreen.append("+");
            }
        });


        substractButton.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                txtScreen.append("-");
            }
        });


        powerOf.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                txtScreen.append("^");
            }
        });


        root.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                txtScreen.append("sqrt(");
            }
        });


        clears.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                txtScreen.setText("");
            }
        });

        parenthesis_left.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                txtScreen.append("(");
            }
        });

        parenthesis_right.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                txtScreen.append(")");
            }
        });


        back.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                if(txtScreen.getText().length() != 0) {
                    String text = txtScreen.getText().substring(0,txtScreen.getText().length()-1);
                    txtScreen.setText(text);
                }
                else {
                    outputScreen.setText("There is nothing to remove!");

                }

            }
        });

    }

    public static void main(String[] args) {

        new Calculator(); // we call the Calculator constructor and start the program.

    }

}