Using Collections and Strings in a Reusable Class - Java Programming: Comprehensive Concepts and Techniques - page 570

134 // Sets password to a new value; keeps current & previous values in history up to max

number

135 public void set ( String pswd ) throws Exception

136 {

137 String encryptPswd;

138 boolean pswdAdded = true ;

139
140 pswd = pswd.trim () ; // remove any leading, trailing white space

141 verifyFormat ( pswd ) ; // verify password was entered properly

142 encryptPswd = encrypt ( pswd ) ; // convert to encrypted form

143
144 if ( !pswdHistory.contains ( encryptPswd )) // if pswd not in recently used list

145 {

146 if ( pswdHistory.size () == maxHistory ) // if list is at max size

147 pswdHistory.remove ( 0 ) ; // remove 1st, oldest, pswd from list

148
149 pswdAdded = pswdHistory.add ( encryptPswd ) ; // add new pswd to end of ArrayList

150
151 if ( !pswdAdded ) // should never happen

152 throw new Exception ( "Internal list error - Password not accepted" ) ;

153
154 if ( expired ) // if pswd has expired,

155 expired = false ; // reset to not expired

156
157 if ( autoExpires ) // if pswd auto expires,

158 remainingUses = maxUses; // reset uses to max

159 }

160 else

161 throw new Exception ( "Password recently used" ) ;

162 }

FIGURE 9-31

164 // Validates entered password against most recently saved value

165 public void validate ( String pswd ) throws Exception

166 {

167 String encryptPswd;

168 String currentPswd;

169 int currentPswdIndex;

170
171 verifyFormat ( pswd ) ; // verify password was entered properly

172 encryptPswd = encrypt ( pswd ) ; // convert to encrypted form

173
174 if ( !pswdHistory.isEmpty ()) // at least one password entry is in history

175 {

176 currentPswdIndex = pswdHistory.size () -1;

177 currentPswd = ( String ) pswdHistory.get ( currentPswdIndex ) ;

178
179 if ( !encryptPswd.equals ( currentPswd )) // if not most recent pswd

180 throw new Exception ( "Password is invalid" ) ;

181
182 if ( expired )

183 throw new Exception ( "Password has expired - please change" ) ;

184
185 if ( autoExpires )

186 {

187 --remainingUses;

188 if ( remainingUses <= 0 )

189 expired = true ;

190 }

191 }

192 else

193 throw new Exception ( "No password on file - list corrupted!" ) ; // should never

happen

194
195
196 }

FIGURE 9-32