New to JAVA: Trying to learn on my own.

import java.math.*;
import java.text.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.JOptionPane;
//import javax.swing.JRadioButton;
//import javax.swing.JRadioButtonMenuItem;
//import java.awt.Graphics;
 
 
 
public class mortgageCalc_v5 extends JFrame implements ActionListener
{
	//Declare buttons and text fields for GUI
	private boolean correct = false;
	private JPanel panel, label;
	private JLabel labelA, labelD, labelF;
	private JTextField textFieldLoanAmount, textFieldLoanTerm;
   private JTextField textFieldInterestRate, textFieldMonthPayment;
	private JTextArea textFieldSched;
   private JButton buttonCalcs;
	private JButton resetCalcs;
	//private JButton exitProgram;
	private JRadioButton yrButton, yr7Button, yr15Button, yr30Button;
 
 
	//Declare variables for calculation
	java.text.DecimalFormat two = new java.text.DecimalFormat("###,###.00");
	NumberFormat currency = NumberFormat.getCurrencyInstance();
	String userChoice;
	int choice;
   double mortgagedAmount, round, count;
	double monthlyPayment, currentBalance, monthlyInterestPaid;
   double loanAmount = mortgagedAmount;
   int result = 0;
	int[] months = {84, 180, 360};
	//double months = 84;
	double[] interestRate = {5.35, 5.5, 5.75};
	//double interestRate = 5.3;
	double intRates = interestRate[choice-1];
	double monthlyInterest = (intRates/100)/12;
	int length = months[choice-1]; 
 
 
public static void main (String[] args)
{
	//Sets the location and title of the panel
   mortgageCalc_v5 label = new mortgageCalc_v5();
   label.setVisible(true);
   label.setTitle("Mortgage Calculator");
	label.setBounds(250,250,415,445);
	label.setResizable(false);
	label.setLocation(600, 300);
	label.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
 
public mortgageCalc_v5()
{
	//Initialize Components
 	panel = new JPanel();
 
 	labelA = new JLabel("Principal ($)");
 	textFieldLoanAmount = new JTextField();
 
	labelD = new JLabel("Monthly Payment");
	textFieldMonthPayment = new JTextField();
	
	labelF = new JLabel("Your Amortization Schedule");
	textFieldSched = new JTextArea();
	
	buttonCalcs = new JButton("Calculate");
	buttonCalcs.setActionCommand ("Calc");
 
	resetCalcs = new JButton("Reset");
	resetCalcs.setActionCommand ("resetCalcs");
 
	//exitProgram = new JButton("Exit");
	
	yrButton = new JRadioButton("");
	
	yr7Button = new JRadioButton("7 years at 5.35% interest");
	yr7Button.setActionCommand ("Case 1");
	
	yr15Button = new JRadioButton("15 years at 5.50% interest");
	yr15Button.setActionCommand ("Case 2");
	
	yr30Button = new JRadioButton("30 years at 5.75% interest");
	yr30Button.setActionCommand ("Case 3n");
	
	textFieldSched = new JTextArea();
	
	
	//Add Listener for calculate, reset and year/interest buttons
	buttonCalcs.addActionListener(this);
	resetCalcs.addActionListener(this);	
	//exitProgram.addActionListener(this);
	yrButton.addActionListener(this);
	yr7Button.addActionListener(this);
	yr15Button.addActionListener(this);
	yr30Button.addActionListener(this);
	
	JScrollPane scrollPane = new JScrollPane (textFieldSched, JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
	JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
 
 
 	//Set Object Attributes
 	textFieldLoanAmount.setEditable(true);
 
   textFieldMonthPayment.setColumns(10);
   textFieldMonthPayment.setEditable(false);
	
	textFieldSched.setEditable(false);
 	textFieldSched.setColumns (200);
 
 
 	//Adds the labels, text fields, and buttons to the panel
 	setContentPane(panel);
	panel.setLayout(null);
 
 	panel.add(labelA);
	labelA.setBounds(10, 10, 140, 25);
 	panel.add(textFieldLoanAmount);
	textFieldLoanAmount.setBounds(115, 10, 90, 25);
 
   panel.add(yrButton);
	yrButton.setBounds(0, 0, 0, 0);
	
	panel.add(yr7Button);
	yr7Button.setBounds(225, 5, 175, 25);
 
	panel.add(yr15Button);
	yr15Button.setBounds(225, 30, 175, 25);
	
	panel.add(yr30Button);
	yr30Button.setBounds(225, 55, 175, 25);
	
	//panel.add(scrollPane);
 
	panel.add(labelD);
	labelD.setBounds(10, 60, 140, 25);
	panel.add(textFieldMonthPayment);
	textFieldMonthPayment.setBounds(115, 60, 90, 25);
	
	panel.add(labelF);
	labelF.setBounds(10, 125, 160, 25);
	panel.add(textFieldSched);
	textFieldSched.setBounds(10, 150, 390, 260);
	
	panel.add(buttonCalcs);
	buttonCalcs.setBounds(228, 95, 88, 25);
	
	panel.add(resetCalcs);
	resetCalcs.setBounds(330, 95, 68, 25);
	
	//panel.add(exitProgram);
	
	
	/***
		This section is used to synch radio buttons so only one is 
		selected at a time.
	***/
	
	ButtonGroup year = new ButtonGroup();
	
	year.add(yrButton);
	year.add(yr7Button);
	year.add(yr15Button);
	year.add(yr30Button);
	
	yrButton.setSelected(true);	
	//year.setSelected(null, true);
}
 
 
public void actionPerformed(ActionEvent event)
{
 
	//Action event for User input of Loan Amount, Years and Interest Rate
	if ("Calc".equals(event.getActionCommand()))
		{
			double monthlyPayment = Calc();
    	}
 
	else if ("resetCalcs".equals(event.getActionCommand()))
        {
            ClearFields ();
        }
}
            public double Calc ()
            //Check for valid numeric imput
			{
				result = 0;
				correct = false;
				while (!correct)
				{
					try
					{
						mortgagedAmount = Double.parseDouble(textFieldLoanAmount.getText());
						if (mortgagedAmount <= 0) throw new NumberFormatException();
						else correct = true;
					}
					catch (NumberFormatException event)
					{
						//Pop-up message indicating error message
						JOptionPane.showMessageDialog(null, "Invalid Entry ... The principal amount must be a positive value and greater than zero!", "Warning!", JOptionPane.ERROR_MESSAGE);
						result = 1;
						correct = true;
			    	}
				}
				
				correct = false;
				while (!correct)
				{
					try
					{
						if (yrButton.isSelected()) throw new NumberFormatException();
						else correct = true;
					}
					catch (NumberFormatException event)
					{
						//Pop-up message indicating error message
						JOptionPane.showMessageDialog(null, "Invalid Entry ... A Year / Interest Rate option needs to be selected!", "Warning!", JOptionPane.ERROR_MESSAGE);
						result = 1;
						correct = true;
			    	}
				} //end While loop
 
				if (result <1)
			    {
				 	for (int i=0; i<1; i++)
					{
						//Calculation for monthly payment
        				monthlyPayment = (mortgagedAmount * monthlyInterest) / (1 - 1 /Math.pow((1 + monthlyInterest), length));
        				currentBalance = mortgagedAmount;  	
			    		textFieldMonthPayment.setText("" + (currency.format(monthlyPayment)));
						
						//User choice code
 
						switch(choice)
							{	
							case 1:
							
							//Format column headers for results to be displayed
										
								textFieldSched.append ("Payment #  \t  Mortgage Payment  \t  Balance Remaining  \t  Interest Payment\n");
						
							//for loop to display Amortization Schedule
 
							for (int month=0; month< length; month++)
								{
							
							//Initialze Variables
 
							monthlyInterestPaid = currentBalance * monthlyInterest;
							currentBalance = (currentBalance - monthlyPayment) + monthlyInterestPaid;
 
							//if statement to set how many lines it should display
 
							if (((month+1) %20) == 0)
							{
 
							try
							{
								Thread.currentThread().sleep(2000);
							}
							catch (InterruptedException e)
							{
								e.printStackTrace();
							}
						
							//Format column headers for results to be displayed
							
							textFieldSched.append ("Payment #  \t  Mortgage Payment  \t  Balance Remaining  \t  Interest Payment\n");
							}
						
							//if statement to print out each monthly payment
 
							if (monthlyPayment <= currentBalance)
								{
									textFieldSched.append ("month  \t  monthlyPayment  \t  currentBalance  \t  monthlyInterestPaid\n");
								}
						
							//if statement to print out the final monthly payment
 
							if (monthlyPayment >= currentBalance)
								{
									textFieldSched.append ("month  \t  monthlyPayment  \t  currentBalance  \t  monthlyInterestPaid\n");
								}
							}
							break;
 
 
							case 2:
							
							//Format column headers for results to be displayed
								
								textFieldSched.append ("Payment #  \t  Mortgage Payment  \t  Balance Remaining  \t  Interest Payment\n");
						
							//for loop to display Amortization Schedule
 
							for (int month=0; month< length; month++)
								{
							
							//Initialze Variables
 
							monthlyInterestPaid = currentBalance * monthlyInterest;
							currentBalance = (currentBalance - monthlyPayment) + monthlyInterestPaid;
 
							//if statement to set how many lines it should display
 
							if (((month+1) %20) == 0)
							{
 
							try
							{
								Thread.currentThread().sleep(2000);
							}
							catch (InterruptedException e)
							{
								e.printStackTrace();
							}
						
							//Format column headers for results to be displayed
							
							textFieldSched.append ("Payment #  \t  Mortgage Payment  \t  Balance Remaining  \t  Interest Payment\n");
							}
						
							//if statement to print out each monthly payment
 
							if (monthlyPayment <= currentBalance)
								{
									textFieldSched.append ("month  \t  monthlyPayment  \t  currentBalance  \t  monthlyInterestPaid\n");
								}
						
							//if statement to print out the final monthly payment
 
							if (monthlyPayment >= currentBalance)
								{
									textFieldSched.append ("month  \t  monthlyPayment  \t  currentBalance  \t  monthlyInterestPaid\n");
								}
							}
							break;
 
 
							case 3:
							
							//Format column headers for results to be displayed
									
									textFieldSched.append ("Payment #  \t  Mortgage Payment  \t  Balance Remaining  \t  Interest Payment\n");
						
							//for loop to display Amortization Schedule
 
							for (int month=0; month< length; month++)
								{
							
							//Initialze Variables
 
							monthlyInterestPaid = currentBalance * monthlyInterest;
							currentBalance = (currentBalance - monthlyPayment) + monthlyInterestPaid;
 
							//if statement to set how many lines it should display
 
							if (((month+1) %20) == 0)
							{
 
							try
							{
								Thread.currentThread().sleep(2000);
							}
							catch (InterruptedException e)
							{
								e.printStackTrace();
							}
						
							//Format column headers for results to be displayed
							
							textFieldSched.append ("Payment #  \t  Mortgage Payment  \t  Balance Remaining  \t  Interest Payment\n");
							}
						
							//if statement to print out each monthly payment
 
							if (monthlyPayment <= currentBalance)
								{
									textFieldSched.append ("month  \t  monthlyPayment  \t  currentBalance  \t  monthlyInterestPaid\n");
								}
						
							//if statement to print out the final monthly payment
 
							if (monthlyPayment >= currentBalance)
								{
									textFieldSched.append ("month  \t  monthlyPayment  \t  currentBalance  \t  monthlyInterestPaid\n");
								}
							}
							break;
						}					
					}
				}
				return mortgagedAmount;
			} // end actionPerformed method
 
			public void ClearFields ()
			{
			    //Set all text fields to blank
			    textFieldLoanAmount.setText ("");
			    //textFieldLoanTerm.setText ("");
			    //textFieldInterestRate.setText ("");
			    textFieldMonthPayment.setText ("");
				 textFieldSched.setText ("");
				 yrButton.setSelected(true);
    		}
}

                                              

1:
2:
3:
4:
5:
6:
7:
8:
9:
10:
11:
12:
13:
14:
15:
16:
17:
18:
19:
20:
21:
22:
23:
24:
25:
26:
27:
28:
29:
30:
31:
32:
33:
34:
35:
36:
37:
38:
39:
40:
41:
42:
43:
44:
45:
46:
47:
48:
49:
50:
51:
52:
53:
54:
55:
56:
57:
58:
59:
60:
61:
62:
63:
64:
65:
66:
67:
68:
69:
70:
71:
72:
73:
74:
75:
76:
77:
78:
79:
80:
81:
82:
83:
84:
85:
86:
87:
88:
89:
90:
91:
92:
93:
94:
95:
96:
97:
98:
99:
100:
101:
102:
103:
104:
105:
106:
107:
108:
109:
110:
111:
112:
113:
114:
115:
116:
117:
118:
119:
120:
121:
122:
123:
124:
125:
126:
127:
128:
129:
130:
131:
132:
133:
134:
135:
136:
137:
138:
139:
140:
141:
142:
143:
144:
145:
146:
147:
148:
149:
150:
151:
152:
153:
154:
155:
156:
157:
158:
159:
160:
161:
162:
163:
164:
165:
166:
167:
168:
169:
170:
171:
172:
173:
174:
175:
176:
177:
178:
179:
180:
181:
182:
183:
184:
185:
186:
187:
188:
189:
190:
191:
192:
193:
194:
195:
196:
197:
198:
199:
200:
201:
202:
203:
204:
205:
206:
207:
208:
209:
210:
211:
212:
213:
214:
215:
216:
217:
218:
219:
220:
221:
222:
223:
224:
225:
226:
227:
228:
229:
230:
231:
232:
233:
234:
235:
236:
237:
238:
239:
240:
241:
242:
243:
244:
245:
246:
247:
248:
249:
250:
251:
252:
253:
254:
255:
256:
257:
258:
259:
260:
261:
262:
263:
264:
265:
266:
267:
268:
269:
270:
271:
272:
273:
274:
275:
276:
277:
278:
279:
280:
281:
282:
283:
284:
285:
286:
287:
288:
289:
290:
291:
292:
293:
294:
295:
296:
297:
298:
299:
300:
301:
302:
303:
304:
305:
306:
307:
308:
309:
310:
311:
312:
313:
314:
315:
316:
317:
318:
319:
320:
321:
322:
323:
324:
325:
326:
327:
328:
329:
330:
331:
332:
333:
334:
335:
336:
337:
338:
339:
340:
341:
342:
343:
344:
345:
346:
347:
348:
349:
350:
351:
352:
353:
354:
355:
356:
357:
358:
359:
360:
361:
362:
363:
364:
365:
366:
367:
368:
369:
370:
371:
372:
373:
374:
375:
376:
377:
378:
379:
380:
381:
382:
383:
384:
385:
386:
387:
388:
389:
390:
391:
392:
393:
394:
395:
396:
397:
398:
399:
400:
401:
402:
403:
404:
405:
406:
407:
408:
409:
410:
411:
412: