CODEWITHSUNDEEP
java
user3516525
user3516525

Reputation: 43

Changed the element of a LinkedList - Need to change the rest

My program is a train schedule showing cities and arrival and departure times. In the program you can type "Delay" and then type the city name and #ofminutes to add a delay in minutes to that cities arrival time. This information is all stored in a LinkedList

Station        Arrival        Departure      Day            
Vancouver      -----          20:30          1              
Kamloops       06:00          06:35          2              
Jasper         16:00          17:30          2              
Edmonton       23:00          23:59          2              
Saskatoon      08:00          08:25          3              
Winnipeg       20:45          22:30          3

My output starts off like this ^^^

So in my 'delay' method I am able to bring up the city specified and add the minutes to the arrival time and everything works great. Code for this is below:

public void delay(String station,int minute){
    String cityDelay=station;
    int timeDelay=minute;
    for(Station list: schedule){
        if (cityDelay.equalsIgnoreCase(list.getCity())){                    
            Calendar c = list.getArrivalDate();                 
            c.add(Calendar.MINUTE, timeDelay);              
            System.out.println(list.getArrival());  //to see if it updated             
        }           
    }               
}

However, it is this point where I have to add those same minutes to the rest of the times on the list but not have it apply those changes to cities before the delay was implemented.

For example, if I type in "Edmonton" and "30", the output should look like this:

Station        Arrival        Departure      Day            
Vancouver      -----          20:30          1              
Kamloops       06:00          06:35          2              
Jasper         16:00          17:30          2              
Edmonton       23:30          00:29          2              
Saskatoon      08:30          08:55          3              
Winnipeg       21:15          23:00          3

(I will figure out how to update the day after I get times working)

I have no idea how to loop through this and apply the update of minutes to the remainder of the list while excluding the elements prior to the selected city. Any looping ideas I can think of would just go through the entire list. Thoughts? Concepts I should look up/google? Thanks in advance.

Upvotes: 2

Views: 136

Answers (3)

Greg Witczak
Greg Witczak

Reputation: 1684

I believe you can use boolean flag to achieve that.

boolean edmontonUpdated = false;
for(Station list: schedule) {
  if ("Edmontion".equals(list.getCity()) || edmontonUpdated == true) {
    Calendar c = list.getArrivalDate();                 
    c.add(Calendar.MINUTE, timeDelay); 
    edmontonUpdated = true;
  }
}

That's just a sample code, you should use some variable instead of "Edmontion" and call boolean edmontonUpdated variable better - but you can do it on your own :)

Upvotes: 0

dvelopp
dvelopp

Reputation: 4295

If you have appache commons collection library or you have own implementation to found element index by predicate, you can make it like this: 

public void delay(String station, int minute) {
    int index = ListUtils.indexOf(schedule, object -> object.getCity().equals(station));
    if (index == -1) {
        return;
    }
    List<Station> updatedStations = schedule.subList(index, schedule.size() - 1);
    updatedStations.forEach(s -> s.getArrival().add(MINUTE, minute));
}

Upvotes: 2

Chetan Jadhav CD
Chetan Jadhav CD

Reputation: 1146

You can use the following modified code to update the arrival times of the cities/stations coming after the city/station for which the delay was added:

public void delay(String station,int minute){
String cityDelay=station;
int timeDelay=minute;
boolean updateRest = false;
for(Station list: schedule){
    if (cityDelay.equalsIgnoreCase(list.getCity())){                    
        updateRest = true;          
    }
    if(updateRest){
        Calendar c = list.getArrivalDate();                 
        c.add(Calendar.MINUTE, timeDelay);              
        System.out.println("City: "+list.getCity()+"Updated Arrival time: "+ list.getArrival());  //to see if it updated   
    }
}
updateRest = false;
}

You can also insert the logic to update the day in the if(updateRest) block if you want to change that too. Hope this helps.

Upvotes: 1

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