Completed Code (Calculator)

package nebulous.tutorial;

import java.awt.EventQueue;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JTextField;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

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

import javax.swing.JRadioButton;
import javax.swing.JLabel;
import javax.swing.JButton;
import javax.swing.JFormattedTextField;
import java.awt.Color;

public class Calculator extends JFrame {

    /*    Completed Calculator Code
     *     By: Ben Ratcliff
     *     
     *     A simple calculator
     * 
     */

    private static final long serialVersionUID = 1L;        // Serial ID Code for JFrame (ignore this)

    // Vars for Jframe (Buttons, textfields, etc)

    private JPanel contentPane;
    private static JTextField answer;
    private static JFormattedTextField input1;
    private static JFormattedTextField input2;
    private static JRadioButton add;
    private static JRadioButton sub;
    private static JRadioButton dev;
    private static JRadioButton mul;
    private static JButton calc;

    // Main function

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {                    // Sets up thread
            public void run() {                                    // Runs thread
                try {
                    Calculator frame = new Calculator();        // New instance of Calculator
                    frame.setVisible(true);                        // Sets frame to visable
                    logic();                                    // Starts logic code
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    // Vars for calculation (inputs / calculations)

    public static float in1 = 0.0f;
    public static float in2 = 0.0f;
    public static float out = 0.0f;

    // Logic method
    // Calls logic functions for calculation

    public static void logic(){

        add.setSelected(true);                                    // Sets add option to enabled by default

        calc.addActionListener(new ActionListener() {            // Adds action listener to calculate button

            @Override
            public void actionPerformed(ActionEvent e) {

                in1 = Float.parseFloat(input1.getText());        // Parses first number to a float, then sets in1 to that number
                in2 = Float.parseFloat(input2.getText());        // Parses second number to a float, then sets in2 to that number

                if(add.isSelected()) out = in1 + in2;            // Sets output to sum
                if(sub.isSelected()) out = in1 - in2;            // Sets output to difference
                if(dev.isSelected()) out = in1 / in2;            // Sets output to quotient
                if(mul.isSelected()) out = in1 * in2;            // Sets output to product

                answer.setText(Float.toString(out));            // Sets answer field to the output
            }

        });

    }


    // Calculator (constructor)
    // Most of this code is generated by WindowBuilder

    public Calculator() {

        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        try {
            UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        } catch (Exception e){
            e.printStackTrace();
        }

        setBounds(100, 100, 390, 400);
        setResizable(false);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        setContentPane(contentPane);
        contentPane.setLayout(null);

        input1 = new JFormattedTextField();
        input1.setFont(new Font("Tahoma", Font.PLAIN, 16));
        input1.setBounds(73, 52, 251, 40);
        contentPane.add(input1);
        input1.setColumns(10);

        input2 = new JFormattedTextField();
        input2.setFont(new Font("Tahoma", Font.PLAIN, 16));
        input2.setColumns(10);
        input2.setBounds(73, 103, 251, 40);
        contentPane.add(input2);

        add = new JRadioButton(" + ");
        add.setBounds(330, 45, 44, 23);
        contentPane.add(add);
        add.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                sub.setSelected(false);
                dev.setSelected(false);
                mul.setSelected(false);
            }

        });

        sub = new JRadioButton(" - ");
        sub.setBounds(330, 69, 44, 23);
        contentPane.add(sub);
        sub.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                add.setSelected(false);
                dev.setSelected(false);
                mul.setSelected(false);
            }

        });

        dev = new JRadioButton(" / ");
        dev.setBounds(330, 95, 44, 23);
        contentPane.add(dev);
        dev.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                sub.setSelected(false);
                add.setSelected(false);
                mul.setSelected(false);
            }

        });

        mul = new JRadioButton(" * ");
        mul.setBounds(330, 120, 44, 23);
        contentPane.add(mul);
        mul.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                sub.setSelected(false);
                dev.setSelected(false);
                add.setSelected(false);
            }

        });

        answer = new JTextField();
        answer.setFont(new Font("Tahoma", Font.PLAIN, 16));
        answer.setBackground(Color.WHITE);
        answer.setBounds(17, 299, 341, 40);
        answer.setEditable(false);
        contentPane.add(answer);
        answer.setColumns(10);

        JLabel lblNum = new JLabel("Num 1");
        lblNum.setFont(new Font("Tahoma", Font.PLAIN, 16));
        lblNum.setBounds(18, 52, 93, 40);
        contentPane.add(lblNum);

        JLabel lblNum_1 = new JLabel("Num 2");
        lblNum_1.setFont(new Font("Tahoma", Font.PLAIN, 16));
        lblNum_1.setBounds(18, 103, 93, 40);
        contentPane.add(lblNum_1);

        JLabel lblBasicCalculator = new JLabel("BASIC CALCULATOR");
        lblBasicCalculator.setFont(new Font("Tahoma", Font.PLAIN, 18));
        lblBasicCalculator.setBounds(18, 5, 286, 41);
        contentPane.add(lblBasicCalculator);

        calc = new JButton("CALCULATE");
        calc.setFont(new Font("Microsoft Sans Serif", Font.BOLD, 16));
        calc.setBounds(18, 158, 342, 89);
        contentPane.add(calc);

        JLabel lblAnswer = new JLabel("Answer:");
        lblAnswer.setFont(new Font("Tahoma", Font.PLAIN, 16));
        lblAnswer.setBounds(16, 253, 93, 40);
        contentPane.add(lblAnswer);
    }
}