I am following the tutorial here:
http://developer.android.com/training/basics/firstapp/starting-activity.html
When I enter some text into the field and press Send, it goes to the second screen with the larger text, so that part works.
When I click the "back" button on my phone, the text I inputted is still in the text field. But if I press the back button on the screen near the top of the program, the text I inputted is gone.
Why is this and how can I control / change this?
Reason for your issue - Your app creates a new instance of activity when you click the back button in your app.
To fix this
In the back button where you call your first activity, add this line of code
intent.setFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);
What happens with this flag ?
When you use this flag, Android looks for an instance of the desired activity in your activity stack, starting from the front of the stack and scanning until it gets to the root/back of the stack. As soon as it finds an instance of the specified activity, it brings that one to the front (ie: if there are multiple instances of the specified activity it will bring to the front the most recent instance).
Related
I would like to create activity in which it would be explained how the app is supposed to be used. On a click on a button, I would like an Activity to be opened which has next and previous buttons on the bottom. So the first screen after the click on a button would show the first instruction and you can press next to see the next instruction which opens a new screen. After going through all the instructions, I would like a Finish button to return back to the main activity.
My question is can this be made in a single activity or is it actually more activities that differ only by the text and pictures they contain?
Yes it can be done in only one activity(actually 2 if you include the main activity).
What you can do is have multiple TextViews, and when the next button is pressed, you can toggle that 1st instruction's visibility
. And so on for the next instructions. The Next/Previous buttons should determine what Textview is currently visible, so they can keep track what Textview to show next. Use switch statement
I am developing a custom launcher/home-screen, thus I am able to hand home-press events.
Sometimes I want it to intercept Home-presses without affecting the visible activity-stack so to speak. When I press home, however, I get to the launcher stack I suppose, but what I want to do then is get back to the last visited activity stack that was shown right before I pressed home. How can I do that?
How can I retrieve and show the activity that was visible right before I pressed home?
I would like to save state of an activity when you navigate away from it. For example, you have Activity A with filled in text on it and you navigate to Activity B using an intent. Well when you go back to Activity A using an Intent you lose all the text you had on that screen.
When I use the soft key back button on most android phones, the screens text stays on there, I would like to mimic that method of keeping the text on screen between navigation.
The last thing I want to do is pass parameters between all my screens, there are a lot of forms and the users dont have to follow a specific nav order.
I have read into the finish(); commands and the FLAG_ACTIVITY_CLEAR_TOP commands and also checked out Common Ware's answer on killing app, but I am not sure how to put this into my app.
Basically, I have a user click a button that takes them to the camera. The user then snaps a photo and it brings them to a layout view. The user then clicks a button that takes them to one of 2 views, depending on a some conditions.
The user is then allowed to either retake a photo, or go to the main menu (depending). My problem is, if the user goes back to the main menu, and snaps another, then another, etc...the activities stack, so when I click the 'Main Menu' button the app goes back through eached stack activity until finally it goes back to the main menu. Is there a way to kill each activity with one of these lines, so even if a user retakes a photo, they will only need to go back once to get to the main menu?
Thanks for anyhelp.
You could use the noHistory flag which would end each activity once you're away from it.
Probably though, what you really want is singleTop launch mode, that will return to your previously opened activity rather than making a new instance of it.
How do I go to previous screen from current screen in Android app? I know there is a back button on phone, but it takes me to beginning screen of my app and I want my buttons on app to work for going back to previous screen.
Back button indeed takes you to previously seen activity on screen, that launched the current one (not by means of back button). If back button takes you to beggining screen of your app means that navigation to your last activity was done from it. Try launching an activity from another one different from start activity.
What really can be problematic is ending application once at start activity by pressing back button and discovering the application switching to activity that lauched start activity (not by means of back button). In this case you should just call finish() inside onDestroy() listener method of your start activity.