Source Code : A simple loan calculator applet

Java Is Open Source Programming Language You Can Download From Java and Java Libraries From http://www.oracle.com. Click Here to download
We provide this code related to title for you to solve your developing problem easily. Libraries which is import in this program you can download from http://www.oracle.com. Click Here or search from google with Libraries Name you get jar file related it

A simple loan calculator applet

   
/*
 * Chapter 9 - Financial Applets and Servlets The Art of Java by Herbert Schildt
 * and James Holmes McGraw-Hill/Osborne 2003
 *  
 */

import java.applet.Applet;
import java.awt.Button;
import java.awt.Graphics;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Label;
import java.awt.TextField;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.NumberFormat;

/*
 * <applet code="RegPay" width=280 height=200> </applet>
 */

public class RegPay extends Applet implements ActionListener {

  TextField amountText, paymentText, periodText, rateText;

  Button doIt;

  double principal; // original princial

  double intRate; // interest rate

  double numYears; // length of loan in years

  /*
   * Number of payments per year. You could allow this value to be set by the
   * user.
   */
  final int payPerYear = 12;

  NumberFormat nf;

  public void init() {
    // Use a grid bag layout.
    GridBagLayout gbag = new GridBagLayout();
    GridBagConstraints gbc = new GridBagConstraints();
    setLayout(gbag);

    Label heading = new Label("Compute Monthly Loan Payments");

    Label amountLab = new Label("Principal");
    Label periodLab = new Label("Years");
    Label rateLab = new Label("Interest Rate");
    Label paymentLab = new Label("Monthly Payments");

    amountText = new TextField(16);
    periodText = new TextField(16);
    paymentText = new TextField(16);
    rateText = new TextField(16);
    // Payment field for display only.
    paymentText.setEditable(false);

    doIt = new Button("Compute");

    // Define the grid bag.
    gbc.weighty = 1.0; // use a row weight of 1
    gbc.gridwidth = GridBagConstraints.REMAINDER;
    gbc.anchor = GridBagConstraints.NORTH;
    gbag.setConstraints(heading, gbc);

    // Anchor most components to the right.
    gbc.anchor = GridBagConstraints.EAST;

    gbc.gridwidth = GridBagConstraints.RELATIVE;
    gbag.setConstraints(amountLab, gbc);
    gbc.gridwidth = GridBagConstraints.REMAINDER;
    gbag.setConstraints(amountText, gbc);

    gbc.gridwidth = GridBagConstraints.RELATIVE;
    gbag.setConstraints(periodLab, gbc);
    gbc.gridwidth = GridBagConstraints.REMAINDER;
    gbag.setConstraints(periodText, gbc);

    gbc.gridwidth = GridBagConstraints.RELATIVE;
    gbag.setConstraints(rateLab, gbc);
    gbc.gridwidth = GridBagConstraints.REMAINDER;
    gbag.setConstraints(rateText, gbc);

    gbc.gridwidth = GridBagConstraints.RELATIVE;
    gbag.setConstraints(paymentLab, gbc);
    gbc.gridwidth = GridBagConstraints.REMAINDER;
    gbag.setConstraints(paymentText, gbc);

    gbc.anchor = GridBagConstraints.CENTER;
    gbag.setConstraints(doIt, gbc);

    // Add all the components.
    add(heading);
    add(amountLab);
    add(amountText);
    add(periodLab);
    add(periodText);
    add(rateLab);
    add(rateText);
    add(paymentLab);
    add(paymentText);
    add(doIt);

    // Register to receive action events.
    amountText.addActionListener(this);
    periodText.addActionListener(this);
    rateText.addActionListener(this);
    doIt.addActionListener(this);

    nf = NumberFormat.getInstance();
    nf.setMinimumFractionDigits(2);
    nf.setMaximumFractionDigits(2);
  }

  /*
   * User pressed Enter on a text field or pressed Compute.
   */
  public void actionPerformed(ActionEvent ae) {
    repaint();
  }

  // Display the result if all fields are completed.
  public void paint(Graphics g) {
    double result = 0.0;

    String amountStr = amountText.getText();
    String periodStr = periodText.getText();
    String rateStr = rateText.getText();

    try {
      if (amountStr.length() != 0 && periodStr.length() != 0
          && rateStr.length() != 0) {

        principal = Double.parseDouble(amountStr);
        numYears = Double.parseDouble(periodStr);
        intRate = Double.parseDouble(rateStr) / 100;

        result = compute();

        paymentText.setText(nf.format(result));
      }

      showStatus(""); // erase any previous error message
    } catch (NumberFormatException exc) {
      showStatus("Invalid Data");
      paymentText.setText("");
    }
  }

  // Compute the loan payment.
  double compute() {
    double numer;
    double denom;
    double b, e;

    numer = intRate * principal / payPerYear;

    e = -(payPerYear * numYears);
    b = (intRate / payPerYear) + 1.0;

    denom = 1.0 - Math.pow(b, e);

    return numer / denom;
  }
}



           
         
    
    
  

Thank with us