GUI Interest calculator in Java

Problem:

Create a GUI interest calculator in java.

Output:

Solution:

import java.awt.Container;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.DecimalFormat;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JScrollPane;
import javax.swing.JSpinner;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.SpinnerNumberModel;

public class Calculator extends JFrame{

 private JLabel amountLabel, rateLabel, yearsLabel, outputLabel;
 private JTextField amountTextField, rateTextField;
 private JButton calculateButton; 
 private JSpinner durationSpinner;
 private JTextArea outputTextArea;
 private JScrollPane scrollPane;
 private JButton clearButton;

 public Calculator() {
  createGUI();
 }
 
 private void createGUI() {
 
  Container contentPane = getContentPane();
  contentPane.setLayout(null);
  
  
  amountLabel = new JLabel();
  amountLabel.setText("Principal");
  amountLabel.setBounds(16, 16, 76, 24);
  contentPane.add(amountLabel);
  
  amountTextField = new JTextField();
  amountTextField.setBounds(108, 16, 100, 24);
  amountTextField.setHorizontalAlignment(JTextField.RIGHT);
  contentPane.add(amountTextField);
  
  calculateButton = new JButton("Calculate");
  calculateButton.setBounds(224, 16, 100, 24);
  calculateButton.addActionListener(new ActionListener() {
  

   @Override
   public void actionPerformed(ActionEvent e) {
    processData();
   }

   private void processData() {
   
    if (amountTextField.getText().length()!=0 && 
      rateTextField.getText().length()!=0) { 
     double principal = 
       Double.parseDouble(amountTextField
       .getText());
     double rate = 
       Double.parseDouble(rateTextField.getText());
     Integer yearsInteger = (Integer) durationSpinner.getValue();
     int yearsint = yearsInteger.intValue();

     DecimalFormat fmt = new DecimalFormat("$#.##");
     double amount;
     outputTextArea.setText("Year\tAmount");

     for (int i = 1; i <= yearsint; i++) {
      amount = principal * Math.pow(1 + rate / 100, i);
      outputTextArea.append("\n" + i + "\t" + fmt.format(amount));
     }
     outputTextArea.setCaretPosition(0);
    }
    
    
   }
  });
  

  contentPane.add(calculateButton);
  
  rateLabel = new JLabel("Interest rate");
  rateLabel.setBounds(16, 56, 76, 24);
  contentPane.add(rateLabel);
  
  rateTextField = new JTextField();
  rateTextField.setBounds(108, 56, 100, 24);
  rateTextField.setHorizontalAlignment(JTextField.RIGHT);
  contentPane.add(rateTextField);
   
  clearButton = new JButton("Clear Data");
  clearButton.setBounds(224, 56, 100, 24);
  clearButton.addActionListener(new ActionListener() {
  
  
   @Override
   public void actionPerformed(ActionEvent arg0) {
    clearData();
   }

   private void clearData() {
    outputTextArea.setText("");
    amountTextField.setText("");
    rateTextField.setText("");
    
    durationSpinner.setValue(new Integer(1));
   }
   
  });
  contentPane.add(clearButton);
  
  
  yearsLabel = new JLabel("Years:");
  yearsLabel.setBounds(16, 96, 76, 24);
  contentPane.add(yearsLabel);
  
  durationSpinner = new JSpinner(new SpinnerNumberModel(1, 1, 10, 1));
  durationSpinner.setBounds(108, 96, 100, 24);
  contentPane.add(durationSpinner);
  
  outputLabel = new JLabel();
  outputLabel.setText("Yearly Account Balance:");
  outputLabel.setBounds(16, 136, 250, 24);
  contentPane.add(outputLabel);
  
  outputTextArea = new JTextArea();
  outputTextArea.setEditable(false);
  scrollPane = new JScrollPane(outputTextArea);
  scrollPane.setBounds(16, 165, 300, 90);
  scrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
  contentPane.add(scrollPane);
  
  
  
  setSize(340 , 300);
  setVisible(true);
  setResizable(false);
  setLocationRelativeTo(null);
 }
 
 public static void main(String[] args) {
   
  Calculator demoFrame = new Calculator();
  demoFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  
 }

}