The SystemLog class represents a list of LogMessage objects and provides a method that removes and returns a list of all log messages (if any) that properly contain a given keyword. The messages in the returned list appear in the same order in which they originally appeared in the system log. If no message properly contains the keyword, an empty list is returned. The declaration of the SystemLog class is shown below.
public class SystemLog
{
/** Contains all the entries in this system log.
* Guaranteed not to be null and to contain only non-null entries. */
private List<LogMessage> messageList;
/** Removes from the system log all entries whose descriptions properly
* contain keyword, and returns a list (possibly empty) containing the removed entries.
* Postcondition:
* -Entries in the returned list properly contain keyword and
* are in the order in which they appeared in the system log.
* -The remaining entries in the system log do not properly contain
* keyword and are in their original order.
* -The returned list is empty if no messages properly contain keyword.
**/
public List<LogMessage> removeMessages(String keyword)
{ /* to be implemented in part (c) */ }
// There may be instance variables, constructors, and methods that are not shown.
}
Write the SystemLog method removeMessages, which removes from the system log all entries whose descriptions properly contain keyword and returns a list of the removed entries in their original order. For example, assume that theLog is a SystemLog object initially containing six LogMessage objects representing the following list of log messages.
CLIENT3:security alert – repeated login failures Webserver:disk offline
SERVER1:file not found
SERVER2:read error on disk DSK1
SERVER1:write error on disk DSK2
Webserver:error on /dev/disk
The call theLog.removeMessages("disk") would return a list containing the LogMessage objects representing the following log messages.
Webserver:disk offline
SERVER2:read error on disk DSK1
SERVER1:write error on disk DSK2
After the call, theLog would contain the following log messages.
CLIENT3:security alert – repeated login failures
SERVER1:file not found
Webserver:error on /dev/disk
