Java The Complete Reference, Seventh Edition

948 Part IV: Applying Java

whererateOfRetspecifies the rate of return,regWDcontains the desired regular withdrawal,

wdPerYearspecifies the number of withdrawals per year, andnumYearsspecifies the length

of the annuity in years.

TheAnnuityapplet shown here computes the initial investment required to produce

the desired annuity. The applet produced by this program is shown in Figure 32-4.

/* Compute the initial investment necessary for

a desired annuity. In other words, it finds

the initial amount needed to allow the regular

withdrawals of a desired amount over a period

of time. */

import java.awt.*;

import java.awt.event.*;

import javax.swing.*;

import java.text.*;

/*

<applet code="Annuity" width=340 height=260>

</applet>

*/

public class Annuity extends JApplet

implements ActionListener {

JTextField regWDText, initialText, periodText,

rateText, numWDText;

JButton doIt;

double regWDAmount; // amount of each withdrawal

double rateOfRet; // rate of return

double numYears; // length of time in years

int numPerYear; // number of withdrawals per year

NumberFormat nf;

public void init() {

try {

SwingUtilities.invokeAndWait(new Runnable () {

FIGURE 32-4

TheAnnuityapplet