I currently have an Android application that displays a schedule for a ferry boat. The application can display the full schedule (just a giant list), but the selling point in the application is it will display when the next two ferries are departing and how long from the current time that departure is.
I am relatively new to Java and currently use large Switch() statements in my code. Basically it gets the current phone time and compares it to all of the times in the schedule at which point it displays the next two departure times and then calculates the difference between current time and the departure times.
I am sure that a switch statement is not the best idea for speed purposes as well as code changing purposes. For example if one time changes its a bunch of lines of code to go in and fix for that one time change. Also if the entire schedule changes everyone has to update their app for the time change to take effect. My ideal situation would be to store a file somewhere on my webserver that could be downloaded and inserted into a hashmap (I think is the correct term) that would load the new schedule if there was a time change.
Not sure how confusing this is, but it would be greatly appreciated if someone could explain how I might use a hashmap or something else you might recommend to get this task accomplished. Currently the variables are the two ferry terminals as well as the day of the week since the schedule changes per day (monday, tues-friday, saturday, sunday).
Below is a screenshot of the application so you can understand it if my post wasn't clear. Thank you in advance.
Screenshot:
Store the schedule objects in a sorted array. You can then binary search the array for the first value greater than the current time. You'll probably use some parent array consisting of the location and applicable day of the week.
You can easily write that kind of data structure to a file that is read & parsed by the application for updates instead of being compiled into the code.
Details of this? First, understand resources in Android. If no updated schedule exists, fall back to the default resource.
Second, use an HTTP head request to check if a newer file exists. If it does, parse, download & save state. Saving Android Activity state using Save Instance State.
Finally, XML is handy for data distribution, even if it's not fast. Everybody understands it and it's easy to update or hand off.
<ferry location=0 time=2045>
<day>1</day>
<day>2</day>
<day>3</day>
<day>4</day>
<day>5</day>
</ferry>
<ferry location=0 time=0800>
<day>6</day>
</ferry>
You will need something like a database to hold the schedule data. That will help you to seperate code from data. I'm not familiar with Android but i think there is a interface to sqlite database on the device.
Further, as this is an application on a small device you may connect to the schedule database on a server thru the internet connection. That way you have to maintain schedule data only in one place (on the server) and clients will use always up to date data.
Related
I hope this makes a bit sense, basically, I have this feature in my app for tracking calories which consists of having this page that only appears the first time you use the feature and it asks you to add personal details (so it can make the right calculations), after that you get faced with a simple page that tracks your nutrition with a button for the user to insert the meals he has eaten, this page has to save the inserted data (via firebase) and then restart from 0 each and every day.
my first problem is I don't know how I make the page that only appears one time to save personal data(to be more precise I don't know how to make only appears the first time). and the second problem is how do I make the app automatically sends the given data at the end of each day?
interface in normal state, interface when adding the meals
hopefully, this 2 images will help you get a better grasp of what am trying to explain
don't worry am not looking for someone to straight up solve it all for me, I just need some orientation about what type of things/functions I need to do to solve these 2 problems
While #Narendra_Nath's answer might work, please note that is not a bulletproof solution. Why? Because a SharedPreferences doesn't persist across app uninstalls. This means that your user can install and uninstall the app and see the page as much as they want. So if you indeed want a user to see a screen only once, then you should consider storing that data in a database. Please note that SQLite isn't also a solution because when a user uninstalls the app, everything that is stored locally is wiped out. So what's the solution?
The best way to solve this would be to store the data in the cloud, either in Cloud Firestore or in the Realtime Database. So you can set a boolean variable and always check against it.
If you however intend to implement Firebase Authentication, then another solution would be to display the screen when your users are authenticated for the first time. So even if they will try to sign in on another device, install and uninstall the app, they won't be able to see the screen again.
Regarding the second problem, you should consider using Cloud Function for Firebase. It's the most elegant solution. If you want to somehow schedule an operation, then you should consider using Cloud Scheduler, as explained in my answer in the following post:
Is it not possible to have a code in the background who will be called every 24h?
Make the page that only appears one-time -> store a value in the shared preferences "isInfoShownToUser -> false" then do a check when the app starts to check if this value is false or true. If it is false show the "take the info" page .. then turn the value to false in the shared preferences.
How do I make the app automatically send data -> Use a Workmanager implementation to send data to the server (Firebase) at a particular time ..
Or use a implementation like the first one which uploads the data to the server just once everyday
I am using S3 Lifecycle Rule to move objects to Glacier. Since objects will be moved to glacier storage I need to make sure my application RDS is also
updated with similar details.
As per my discussion over this thread AWS Lambda for objects moved to glacier, there is no way currently to generate SQS notification to get notified about object being moved to glacier.
Also, as per my understanding currently Lifecycle rule will be evaluated once in a day, but there is not specific time when this will happen in a day. If there was i was planning to have a scheduler which will run after that and update status of archived objects in RDS.
Is there a way that you can suggest which will be close enough to sync this status changes between AWS & RDS?
Let me know your feedback or if you need more information on this to understand use case.
=== My Current approach is as per below.
Below is exact flow that I have implemented, please review and let me know if there is anything that could have been done in better way.
When object is uploaded to system I am marking it with status Tagged and also capturing creation date. My Lifecycle rule is configured with 30 days from creation. So, I have a scheduler which calculates difference between today's date and object creation date for all objects with status Tagged, and check if diff is greater than equal to 30. If so, it updates status to Archived.
If user performs any operation on object with status Archived, we explicitly check in s3 whether object is actually moved to glacier or not. If not we perform operation requested. If moved to glacier we initiate restore process and wait for restore to finish to initiate operation requred.
I appreciate your thoughts and would like to hear your inputs on above approach that i have taken.
Regards.
If I wanted to implement this, I would set the storage class of the object inside my database as "Glacier/Archived" at the beginning of the day it is supposed to transition.
You already know your lifecycle policies, and, as part of object metadata, you also know the creation time of each object. Then it becomes a simple query, which can be scheduled to run every night at 12:00 AM.
You could further enhance your application by defining an algorithm that checks if an object has transitioned to Glacier today, at the moment when object access is requested, it would go and explicitly check if it is actually transitioned or not. If it is marked as Glacier/Archive for more than a day, then checking is no longer required.
Of course, if for any reason, the above solution doesn't work for you, it is possible to write a scanner application to continuously check the status of those objects that are supposed to transition at "DateTime.Today" and are not marked as Glacier/Archive yet.
Trying to make an app in android studio that works as a fitness helper/tracker. On a daily basis and multiple times a day, the user enters data regarding their diet/exercise. Prior to doing so, the user selects which day they're currently on, making the data they input specific to the chosen date. I want to give users the ability to retrieve any available data for a specific day on demand.
I don't quite think sharedPreferences would work, so I was thinking about just saving to internal storage as a text file. The problem is that 1) with all the different files that would be created for even a single day, I feel that it would get messy and 2) I'm not sure how how to retrieve the specific file I'd need, parse it, then output the parsed data graphically if I'm only using a single constructor to make each text file.
I haven't yet delved deeply into using a SQLite DB, it seemed somewhat excessive for this, so I'm hoping someone can either help me figure out a better way to solve the problem or enlighten me as to a more efficient method.
Thanks in advance!
I wanted to learn more about the Android Services / Broadcasts, so I started a simple project, to create a battery monitoring app. It turned out pretty good, I'm using it for a few days now, but I want to add a new function: to show since when is the phone charging/discharging.
First I thought that I would create two static fields in my BoradcastReciever extension class, where I get and publish the data about the battery, one for the actual state (charging/discharging), and one for the time, when the change in state happened. This way, I could just subtract from the current time the last change, and know exactly since when is the phone charging/discharging.
But there is a problem with this solution: It won't show the correct data at first, when a user starts the app. I wouldn't make a big deal of it, but I saw that Android tracks this data somewhere, because inside my phone settings I found this information, so why take the hard way.
So my question is: is there an easy way to get from the Android system the date/time (no matter what format) of the last charging state change?
I looked at the BatteryManager reference but there are no constants named after what I seek, and which I could use, to get the information from the Intent of my receiver.
The Android OS tracks the connect/disconnect of a power source, but does not make this data accessible to apps. You have to record this all yourself, using intent filters.
The two intent filters to use are android.intent.action.ACTION_POWER_CONNECTED and android.intent.action.ACTION_POWER_DISCONNECTED; with these, you can monitor when the power source is connected and disconnected.
You can find information about this process explained incredibly clearly here. Another blog describing the process can be found here.
I finished first year comp sci. And i want to spend some time working on the things they have taught us in the first year (lot of java and a bit of C)...
Anyways as a project, i wanted to do something i need, and what i need is a program to run through my movie folder and get the ratings and some basic info from IMDB...
I'm not sure where to start, i think i can handle the parts about reading the folder names, getting rid of the junk from the name to get the actual name and stuff.. Also i can handle the GUI but i don't know how i can talk to IMDB... what steps should i take to complete this project. I have about a month before school starts and i want to finish it before then...Thanks for all the input
EDIT:
Also can you guys tell me what i should start with and then move on to what? As in should i start with the GUI first or have the code that reads in the folder names and filters the names... I only wrote one program as an assignment in school and it was basically outlined step by step so i just wanna know what i should start with
You've made a very good start by decomposing the problem, identifying the kind of components you need and focusing on (an important) one that you don't know how to do.
The IMDB API is documented here and you can see that it amounts to sending simple HTTP requests with some paramters and getting back some formatted data, possibly as a JSON string.
You will find libraries to help with doing those two things. Even if there are public domain wrappers for accessing IMDB I'd recommend attempting to use general purpose HTTP and JSON libraries - that's probably a better educational exercise.
I'm the author of the IMDB API you are dicussing ;) I limit requests to 30 per hour to stop people hammering. I have yet to have a legitimate reason to perform more requests than that. My suggestion to anyone is to write a batch script to perform 1 request every 2minutes and then leave it going for a few hours overnight. Then you only have to perform a request on demand whenever you add a new movie.