We have been learning how to open new Activities, in class, but so far the second activity runs its logic from the OnCreate() class.
I am wanting to return directly to activity one, from activity two, but run a function in its java when I do so.
All I've been able to find on the matter is how to effectively write my own "back" button.
I am needing to pass a string, as well as an int, that was originally sent from activity one to activity two. I need to compare the received int with the sent int to confirm it is coming from the same source.
My biggest problem is that we were taught to use OnCreate(). This will not work on returning to an Activity, as OnCreate only runs when the instance is first created. If I am creating the instance as I move back, my other function will not work.
You can just use an startActivityForResult method.
Here is a topic of that: How to manage `startActivityForResult` on Android?
Hope it helps :)
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I am working on an app in which i'm sending data to another activity via intent . is it possible that after launch of new activity data transfer (updates) continue to receive by new activity? links would be appreciated thanks in advance.
If another activity is loaded, then the previous one goes on the onPause state.
It wouldn't be accurate expecting anything from a paused activity.
Depending on the case and the function of the second activity, you could either use a service, or depending on your case, you might also be able to use fragments and stick with one activity.
An example of your code would be helpful to understand the case.
I'm a beginner Android developer. I'm still learning new things every day, and while learning I have heard this question quite frequently: What will happen if we send View object as parameter within OnCreate Method? I have searched about it but didn't find anything helpful. I just want to know is it really possible and if so then please explain the scenario.
oncreate() called when the activity is first created. This is where you should do all of your normal static set up: create views, bind data to lists, etc. This method also provides you with a Bundle containing the activity's previously frozen state.
I am writing an Android App and i need to display some results from a non-activity class.
Basically my App gets the current location, activity and other things, and on those i run some functions, for example to check if the user has been at that place before.
Anyway, an intent triggers these functions, and at the end of the function I want to update a TextView with the result of these functions.
But it doesn't seem to work from anywhere besides MainActivity. I tried making the TextView static, but that doesn't seem to work, and returning the results to MainActivity is not possible either in since it is not called directly from MainActivity.
Does some have an idea on how to solve this problem?
This is my first android project, so there's still a lot of thing i don't know about. Thank you!
I don't know exactly what your code looks like, but do you have a model class that holds all your data (for example, some kind of singleton)? If so, you could just save the updated text there, and then update the TextView in a callback method.
If that doesn't fit what you're doing, I would considering refactoring your code so that the text you want is sent back to your MainActivity. You mentioned that the method is not called directly, but could your calculations pass the text to an intermediate class, which passes it to your MainActivity?
You should not update the ui drom background thread.
If you want to update the ui from background thread use Handlers,AsyncTask or use some other thread concepts.
If you want to update the UI fro Service or Broadcast receiver for eg you receive a message inside onReceive of broadcasrReceiver now to update the ui use sendBroadcast and inside your activity registet a dynamic Broadcast receiver and then update
I'm confused regarding with some basic android development concepts, my question is not pointing at a particular code, thats why I dont include any.
Let's say that I have an activity inside of which I have a container in which I load a couple fragments (they are multiple instances of the same fragment), now the activity is populated, and inside one fragment I press a button that opens a new activity, it doesn't matter what may happen in that activity, the thing is that when I press a button it should take me back to the previos activity, I know that pressing the back button or using .finish(); will take me back to my already-populated activity, but I want to know, if that is the correct thing to do, or should I finish the activity as soon as i leave to the next one and when I want to go back create a new instance and repopulate it, if so, where should i store the variables?
Let's say that the fragments that I mentioned are "alarms" for an alarm application, and when I create it I call AlarmFragment newAlarm = new AlarmFragment(); and then I add that alarm to an arrayList in my alarms activity (java class) getListOfAlarms().add(getAlarmsAmount(), frag); which remains on the activity that has the fragment container, the question is, are these variables created in the right place? Because I am leaving them inside the activity itself right? What could happen if the activity is destroyed? I've been told that I should create an SQL database for storing those variables. I am not talking about long term saving but variables that I will be using at runtime
Can someone explain me these concepts a little bit? A link to a place where it is explained will be great too.
Your question seems like it has many parts.
In Part 1, this is what I think you are talking about:
1) how you decide to allow the user to get back to the first activity is really up to you. And 2) what you leave in the Back Stack is also up to you and what you want to define for the users' capabilities within your app. For example, if you want them to only be able to use a button that you define inside Activity 2 container, that is fine. However, you are not required to provide a button in Activity 2, and you are certainly allowed to use the Up Action in the App Bar for navigation. If I were you, I would read more about the Tasks and the Back Stack http://developer.android.com/guide/components/tasks-and-back-stack.html
You also mention this idea of having to "finish an Activity" with .finish(). I don't think that is usually necessary, but it is available to you if you want to use it based on what you decide for your app's logic (and what the user should and shouldn't be able to do).
With the Back button, Activity 1 will appear as if just initialized when you get back from Activity 2. Try it out. Also run some Log statements based on the simple diagram I provided and the Lifecycle "callbacks" (put these methods in your Activities and throw a Log statement in each to get a better sense of where you are in the Lifecycle) http://developer.android.com/guide/components/activities.html#Lifecycle
As for Part 2 of your question, I would try/set-up some of the above first, then start to experiment with a single variable to see what happens to it between Activities. There are a lot of "what ifs" to your question. You don't necessarily have to create a DB to store your variables, but that could certainly be an option. Take a look at the Developer Guide for most of the Data Storage options: http://developer.android.com/guide/topics/data/data-storage.html
If you are concerned about losing data when the Activity is destroyed, I might consider creating a database. Read the following for more info on recreating an Activity when you have gone elsewhere and are returning: http://developer.android.com/training/basics/activity-lifecycle/recreating.html In particular Saving Your Activity State: http://developer.android.com/training/basics/activity-lifecycle/recreating.html#SaveState
There's also an SO post on this: Saving Android Activity state using Save Instance State
This may be in the RTFM category but I can’t seem to figure out the proper way to do this. One of my activities shows some random data from a database, it uses some user-defined search-criteria from a previous activity to filter out which data blocks to search from. But it’s main purpose is to display the data, and present the user with a UI to manipulate the data to his will.
The user can also bookmark this random data, and then access it later again (the bookmarks show up in a listview in another activity). Rather than creating a whole new activity with basically the same purpose, I want to reuse the one already created, and just tell it that I want to view some data, rather than search for some new. So what is the proper way of informing an activity of want you want to do? Should that be defined in the Intent extras bundle or is there another way?
Or would the proper way be to create a new activity for this?
You can extend the first Activity like this:
ActivityB extends ActivityA
and then the methods that need to be different in ActivityB can #override the methods in ActivityA, but methods that do the same thing, you don't have to dupe as long as they're protected.