Calculator.

//Calculator.java

package net.discfiresoftworks.calculator;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;

import javax.swing.BorderFactory;
import javax.swing.BoxLayout;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class Calculator extends JFrame
{
    private static final long serialVersionUID = 1L;

    public JPanel wrapper = new JPanel();
    public static JTextField calc = new JTextField();
    public JPanel buttons = new JPanel();
    public JPanel funcs = new JPanel();
    public JPanel nums = new JPanel();
    public JPanel bln1 = new JPanel();
    public JPanel bln2 = new JPanel();
    public JPanel bln3 = new JPanel();
    public JPanel bln4 = new JPanel();

    public static ArrayList<String> calculate = new ArrayList<String>();

    public static void main(String[] args)
    {
        new Calculator();
    }

    public Calculator()
    {
        this.setSize(200, 220);
        this.setResizable(false);
        this.setTitle("Calculator");
        this.setDefaultCloseOperation(3);
        this.setLocationRelativeTo(null);
        this.setLayout(new BorderLayout());

        wrapper.setBorder(BorderFactory.createLineBorder(Color.WHITE, 5));
        wrapper.setLayout(new BorderLayout());

        calc.setBorder(BorderFactory.createEtchedBorder());

        StyledButton point = new StyledButton(".");
        point.addActionListener(new ActionListener(){
            @Override
            public void actionPerformed(ActionEvent e)
            {
                calc.setText(calc.getText() + ".");
            }
        });

        bln1.add(new NumButton(calc, 7));
        bln1.add(new NumButton(calc, 8));
        bln1.add(new NumButton(calc, 9));

        bln2.add(new NumButton(calc, 4));
        bln2.add(new NumButton(calc, 5));
        bln2.add(new NumButton(calc, 6));

        bln3.add(new NumButton(calc, 1));
        bln3.add(new NumButton(calc, 2));
        bln3.add(new NumButton(calc, 3));

        bln4.add(new NumButton(calc, 0));
        bln4.add(point);

        nums.setLayout(new BoxLayout(nums, BoxLayout.Y_AXIS));
        nums.add(bln1);
        nums.add(bln2);
        nums.add(bln3);
        nums.add(bln4);

        StyledButton clear = new StyledButton("C");
        clear.addActionListener(new ActionListener(){
            @Override
            public void actionPerformed(ActionEvent e)
            {
                calculate.clear();
                calc.setText(null);
            }
        });

        StyledButton equals = new StyledButton("=");
        equals.addActionListener(new ActionListener(){
            @Override
            public void actionPerformed(ActionEvent e)
            {
                ans();
            }
        });

        funcs.setLayout(new GridLayout(4, 2));
        funcs.add(clear);
        funcs.add(new FuncButton("%", calc));
        funcs.add(new FuncButton("*", calc));
        funcs.add(new FuncButton("÷", calc));
        funcs.add(new FuncButton("√", calc));
        funcs.add(new FuncButton("-", calc));
        funcs.add(new FuncButton("+", calc));
        funcs.add(equals);

        buttons.setLayout(new BorderLayout());
        buttons.add(nums, "West");
        buttons.add(funcs, "East");

        calc.setEditable(false);

        wrapper.add(calc, "North");
        wrapper.add(buttons, "Center");

        this.add(wrapper, "Center");

        this.setVisible(true);
    }

    public static void ans()
    {
        Double cV = Double.parseDouble(calculate.get(0));

        System.out.println("Hi");

        for(int i = 1; i < calculate.size(); i += 2)
        {
            System.out.print(calculate.get(i) + ", " + calculate.get(i + 1) + ", ");

            switch(calculate.get(i))
            {
                case "+":
                    cV += Double.parseDouble(calculate.get(i + 1));
                    break;
                case "-":
                    cV -= Double.parseDouble(calculate.get(i + 1));
                    break;
                case "*":
                    cV *= Double.parseDouble(calculate.get(i + 1));
                    break;
            }
        }

        calc.setText("= " + cV);
    }

    public static void addTo(String toAdd)
    {
        try{
            if(!isNumeric(toAdd))
            {
                if(!isNumeric(calculate.get(calculate.size() - 1)))
                {
                    calculate.set(calculate.size() - 1, toAdd);
                }
            }else{
                calculate.add(toAdd);
            }
        }catch(Exception e){ }
    }

    public static boolean isNumeric(String str)
    {
        try{
            Double.parseDouble(str);
        }catch(NumberFormatException nfe){
            return false;
        }
        return true;
    }
}


//NumButton.java

package net.discfiresoftworks.calculator;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JTextField;

public class NumButton extends StyledButton
{
    private static final long serialVersionUID = 1L;

    public NumButton(final JTextField f, final int num)
    {
        super("" + num);

        this.addActionListener(new ActionListener(){

            @Override
            public void actionPerformed(ActionEvent arg0)
            {
                f.setText(f.getText() + num);
            }

        });
    }
}

//FuncButton.java

package net.discfiresoftworks.calculator;

import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JTextField;
import javax.swing.border.Border;

public class FuncButton extends JButton
{
    private static final long serialVersionUID = 1L;

    public FuncButton(final String func, final JTextField f)
    {
        super(func);

        this.setSize(15, 15);

        Border c = null;

        if(!func.equals("-"))
        {
             c = BorderFactory.createCompoundBorder(BorderFactory.createEtchedBorder(), BorderFactory.createLineBorder(Color.WHITE, 6));
        }else{
            c = BorderFactory.createCompoundBorder(BorderFactory.createEtchedBorder(), BorderFactory.createLineBorder(Color.WHITE, 7));
        }

        this.setBorder(BorderFactory.createCompoundBorder(BorderFactory.createLineBorder(Color.white, 1), c));

        this.addActionListener(new ActionListener(){

            @Override
            public void actionPerformed(ActionEvent e)
            {
                Calculator.addTo(func);
                Calculator.addTo(f.getText());
                f.setText(func + " ");
            }

        });
    }
}

//StyledButton.java

package net.discfiresoftworks.calculator;

import java.awt.Color;

import javax.swing.BorderFactory;
import javax.swing.JButton;

public class StyledButton extends JButton
{
    private static final long serialVersionUID = 1L;

    public StyledButton(String str)
    {
        super(str);

        this.setBorder(BorderFactory.createCompoundBorder(BorderFactory.createEtchedBorder(), BorderFactory.createLineBorder(Color.WHITE, 5)));
    }
}