Can someone please answer my question at:
h t t p : / / g o o . g l / 3 v Z h m A (remove the spaces. I don't have rights to post a web link. it's not spam)
The answer will likely be trivial to the more seasoned Android developers but I've burnt days on this.
Thanks.
lukeallison said:
Can someone please answer my question at:
h t t p : / / g o o . g l / 3 v Z h m A (remove the spaces. I don't have rights to post a web link. it's not spam)
The answer will likely be trivial to the more seasoned Android developers but I've burnt days on this.
Thanks.
Click to expand...
Click to collapse
You are trying to update a TextView that exists on a fragment from the Activity code.
You can access the fragment TextView only from the fragment code.
So what you need to do the following:
- Add a public method to the fragment that receive a value and update the fragment TextView.
- From the Activity code, retrieve the current displayed fragment from the ViewPager adapter, and call its public method to update the value.
alphascript said:
You are trying to update a TextView that exists on a fragment from the Activity code.
You can access the fragment TextView only from the fragment code.
So what you need to do the following:
- Add a public method to the fragment that receive a value and update the fragment TextView.
- From the Activity code, retrieve the current displayed fragment from the ViewPager adapter, and call its public method to update the value.
Click to expand...
Click to collapse
Would you mind explaining that second step?
I created the method inside the fragment as follows:
public void changeText(View rootView, int seconds)
{
((TextView)rootView.findViewById(R.id.timer)).setText(seconds);
}
You need to create custom view pager that extend FragmentStatePagerAdapter.
This view pager will cache the fragments that are currently initiated and their position.
Add the view pager a method that receive view position as parameter (use the view pager getCurrentItem() to retrieve the current position) and return the fragment at the position.
Once you will get the instance of the currently displayed fragment, cast it type to your fragment type, and call the method you've added to update the TextView.
alphascript said:
You need to create custom view pager that extend FragmentStatePagerAdapter.
This view pager will cache the fragments that are currently initiated and their position.
Add the view pager a method that receive view position as parameter (use the view pager getCurrentItem() to retrieve the current position) and return the fragment at the position.
Once you will get the instance of the currently displayed fragment, cast it type to your fragment type, and call the method you've added to update the TextView.
Click to expand...
Click to collapse
Can I discuss this with in more detail by email or private message?
Related
Hi guys,
On a button click I am inflating a layout like so:
Code:
public void plusLayout(View v) {
// inflating layout here:
LinearLayout ll1 = (LinearLayout) findViewById(R.id.main_layout);
// this layout is being inflated:
View newView = getLayoutInflater().inflate(R.layout.layout_to_be_added, null);
// add layout
ll1.addView(newView);
}
But when the activity restarts, the inflated layouts are gone.
I'd like the layouts to stay there.
(The user can click a button to remove the layout by hand).
I must be missing something trivial here right?
Cheers,
Daan
Which way is it restarted?
If the complete app is restarted, a new layout will be set in the onCreate method.
nikwen said:
Which way is it restarted?
If the complete app is restarted, a new layout will be set in the onCreate method.
Click to expand...
Click to collapse
Yeah when you press back button and start the app again or completely kill it.
It also happens on orientation change as the activity get restarted then as well.
But I think you can override that in the manifest somewhere.
DaanJordaan said:
Yeah when you press back button and start the app again or completely kill it.
It also happens on orientation change as the activity get restarted then as well.
But I think you can override that in the manifest somewhere.
Click to expand...
Click to collapse
Ah ok.
The point is: If you open the app or turn your device, the onCreate method is called. There you set a completely new layout. You would need to save that the layout is inflated (you could use a SharedPreferences entry) and inflate it in the onCreate method. If you just want it to appear again after turning the device, use the onSaveInstanceState method and the onRestoreInstanceState method. That would be better practice.
Look at the activity lifecycle.
Just so I'm sure I get this right :
The user launches the app, the layouts are not inflated
He presses a button which calls your plusLayout() method, so the layouts are now inflated
The user quits the activity and restarts it, the layouts are not inflated anymore but you want them to.
Is that correct ?
If it is, 2 ways I can think of :
Overriding savedInstanceState() & onRestoreInstanceState() :
First, declare a private Boolean before the onCreate() of your activity :
Code:
private Boolean isInflated = false;
Then, set it to true in the onClick() of your button, and override savedInstanceState and onRestoreInstanceState like so :
Code:
@Override
public void onSaveInstanceState(Bundle savedInstanceState) {
super.onSaveInstanceState(savedInstanceState);
// Save state changes to the savedInstanceState.
// This bundle will be passed to onCreate if th activity is
// killed and restarted.
savedInstanceState.putBoolean("inflate", isInflated);
}
Code:
@Override
public void onRestoreInstanceState(Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
// Restore UI state from the savedInstanceState.
// This bundle has also been passed to onCreate.
Boolean myBoolean = savedInstanceState.getBoolean("inflate");
if (myBoolean == true)
plusLayout(myView);
}
Using the sharedPreferences
Same logic, different way to save the boolean :
Before onCreate(), declare a private boolean and a private SharedPreferences :
Code:
private Boolean isInflated = false;
private SharedPreferences prefs = getSharedPreferences("MY_PREFS");
in the onClick of your button :
Code:
isInflated = true;
Editor e = prefs.edit();
e.putBoolean("inflate", isInflated);
e.commit();
Then, in your onCreate(), retrieve the stored value and if it's true, call your plusLayout() method :
Code:
Boolean doInflate = prefs.getBoolean("inflate", false // this is the default value);
if (doInflate == true)
plusLayout(myView);
nikwen said:
Ah ok.
The point is: If you open the app or turn your device, the onCreate method is called. There you set a completely new layout. You would need to save that the layout is inflated (you could use a SharedPreferences entry) and inflate it in the onCreate method. If you just want it to appear again after turning the device, use the onSaveInstanceState method and the onRestoreInstanceState method. That would be better practice.
Look at the activity lifecycle.
Click to expand...
Click to collapse
Okay I'm working on that at the moment.
Whenever a layout is created an (int) "counter" get incremented.
I will save this "counter" in the SharedPreferences.
When the app starts layouts get created "counter" times.
Is this good practice?
It seems so strange that there isn't an easier way to save layout/activity states.
Edit:
Androguide.fr said:
Just so I'm sure I get this right :
The user launches the app, the layouts are not inflated
He presses a button which calls your plusLayout() method, so the layouts are now inflated
The user quits the activity and restarts it, the layouts are not inflated anymore but you want them to.
Is that correct ?
Click to expand...
Click to collapse
That is correct. Big thanks for the examples.
DaanJordaan said:
Okay I'm working on that at the moment.
Whenever a layout is created an (int) "counter" get incremented.
I will save this "counter" in the SharedPreferences.
When the app starts layouts get created "counter" times.
Is this good practice?
It seems so strange that there isn't an easier way to save layout/activity states.
Edit:
That is correct. Big thanks for the examples.
Click to expand...
Click to collapse
I would use his snippets. They are good (as always). Decide which one to use by what I have given above:
Just for turning:
onSaveInstanceState and onRestoreSavedInstanceState
For turning and reopening:
Shared preferences
Guys. Help me. I'm learning to ''Respond to the Send Button'' but I don't know what to do. I follow this step but I still can't understand.
http://developer.android.com/training/basics/firstapp/starting-activity.html
If you guys can help me, I'm really grateful.
Merivex95 said:
Guys. Help me. I'm learning to ''Respond to the Send Button'' but I don't know what to do. I follow this step but I still can't understand.
http://developer.android.com/trainin...-activity.html
If you guys can help me, I'm really grateful.
Click to expand...
Click to collapse
That link didn't work, but if you Google 'android java button onclick listener' that will get you started with plenty of helpful links.
When the button is clicked, you then need to check the content of the Edit Text field - Something like this:
Code:
public void onClick(final View v) {
final String commandText = inputText.getText().toString();
if (commandText != null && commandText.length() > 0) {
Where inputText is the Edit Text field you've assigned in your OnCreate method.
Getting started involves a lot of head scratching, but don't give up! There's so much Open Source code out there, that the penny will drop soon.
brandall said:
That link didn't work, but if you Google 'android java button onclick listener' that will get you started with plenty of helpful links.
When the button is clicked, you then need to check the content of the Edit Text field - Something like this:
Code:
public void onClick(final View v) {
final String commandText = inputText.getText().toString();
if (commandText != null && commandText.length() > 0) {
Where inputText is the Edit Text field you've assigned in your OnCreate method.
Getting started involves a lot of head scratching, but don't give up! There's so much Open Source code out there, that the penny will drop soon.
Click to expand...
Click to collapse
OMG !! this is the link : http://developer.android.com/training/basics/firstapp/starting-activity.html
I don't know how to compile the code properly. hummmm ... maybe you can help me by correcting my code ?
Paste code (variables, functions, etc) inside your MainActivity class and don't write 3 dots, it's just a replacement for skipped parts
Mikanoshi said:
Paste code (variables, functions, etc) inside your MainActivity class and don't write 3 dots, it's just a replacement for skipped parts
Click to expand...
Click to collapse
Ohhh yeahhh :cyclops: .. how can I be so stupid
btw ,, where should I put this code ?
code:
Code:
@override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Get the message from the intent
Intent intent = getIntent();
String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);
// Create the text view
TextView textView = new TextView(this);
textView.setTextSize(40);
textView.setText(message);
// Set the text view as the activity layout
setContentView(textView);
}
Code:
Merivex95 said:
btw ,, where should I put this code ?
Click to expand...
Click to collapse
Replace existing onCreate function with it.
Mikanoshi said:
Replace existing onCreate function with it.
Click to expand...
Click to collapse
But I get an error after doing that ..
Merivex95 said:
But I get an error after doing that ..
Click to expand...
Click to collapse
You need to import TextView and Intent first. Just hover over the names and select import from the menu you will see.
Seriously, my advice would be to learn and understand Java first. It doesn't make sense to learn Android if you don't know Java (and it won't work).
nikwen said:
You need to import TextView and Intent first. Just hover over the names and select import from the menu you will see.
Seriously, my advice would be to learn and understand Java first. It doesn't make sense to learn Android if you don't know Java (and it won't work).
Click to expand...
Click to collapse
Thanks for the advice
nikwen said:
It doesn't make sense to learn Android if you don't know Java (and it won't work).
Click to expand...
Click to collapse
Unless you know any other similar languages. Java was the easiest lang to learn for me, after years of writing on Object Pascal/Object C/C++/JavaScript/PHP. The most troublesome part of coding for Android is creating an UI, especially cross-version compatible :laugh:
My app uses the ActionBarCompat and NavigationDrawer, which begs the question of how is one supposed to structure the navigation? I see two options:
1) Use a single Activity and swap out Fragments.
2) Use multiple Activities, and transition between them.
The latter seems to be the correct way, however this means that each Activity must get and build the ActionBar and NavigationDrawer when called from another Activity.
How will this affect my transition animations? If I have a left-to-right transition effect when a navigation item is clicked, will it transition the entire Activity or everything below the ActionBar?
The former seems fraught with issues. A single .java class file could get really heavy and difficult to manage.
But while we're on the subject of Fragments, please consider this situation and school me on proper Fragment management:
A blank Activity with just a LinearLayout attaches a new Fragment to it that contains a Button. Inside the Fragment class, this button gets an onClickListener and when the button is clicked, another of the same kind of Fragment should be attached to the LinearLayout inside the Activity.
A) Should the Fragment class communicate to the Activity that a new Fragment should be attached? This could be done with a custom public interface and the callback being executed within the onClickListener in the Fragment class.
B) Or, should the Fragment handle attaching the new instance inside the onClickListener, making the Activity work less? By simply bridging the clicked Button and calling .getParent() until the LinearLayout is reached, then attaching it there.
The correct way is the former. You should use fragments with the navigation drawer. If you use activities you are going to setup the navigation drawer every new activity. You should open other fragments from the activity and not from the fragment itself. I believe their is a tutorial on the android developer site that explains this in depth. A quick Google search for "android fragment to fragment communication" or something like that should get you to it. I'll try and find a link later when I am on my computer if you don't find anything
Sent from my Nexus 7 using XDA Premium HD app
I have a TableLayout with a table. How can I set onClicklisteners for each cell of this table?
I have not found any proper solution for this problem.
kovacsakos91 said:
I have a TableLayout with a table. How can I set onClicklisteners for each cell of this table?
I have not found any proper solution for this problem.
Click to expand...
Click to collapse
You'd usually set each view in each TableRow to be clickable (via android:clickable="true" in xml oder via view.setClickable(true); in java).
In xml, you then override the androidnClick attribute with your methods name, but if yuo want to have real onClickListeners you should call view.setOnClickListener(mListener);
To seperate the clicks in the onClick method, you should get the id's like this:
Code:
public void onClick(View v){
// switch case the id's:
switch(v.getId(){
case R.id.someId:
// do something in response;
break;
}
// for getting the id of the parent TableRow, use
int rowId = ((TableRow) v.getParent()).getId();
}
Depending on what you want to display in the table, you could also use Buttons for that.
Hi guys,
i've started making an app recently.. and i needed a task to run in the backgound every 2 or 5 minutes.. and i collect the data and i display it when the app is opened.. so am using a sync task.... I'm having a bit of diffculty unerstanding how its used as every example is different..
and FYI am using a seperate .java file to runt he asynctask...
When we go through the android developers page this is the code we see...
They start with
Code:
private class DownloadFilesTask extends AsyncTask<URL, Integer, Long> {
1) whats the deal with the URL Integer Long ????? If i skip it what will happen???
next is this
Code:
protected void onProgressUpdate(Integer... progress) { setProgressPercent(progress[0]);
2) whats the integer doig there?? even if its not used in the function they put it... whats the deal??
3) Also how do we pass values like strings to a class??? i know about functions but the functions used in this class are like a group like so i cant exactly pass values to just one particular function...
Async Task
nvyaniv said:
Hi guys,
i've started making an app recently.. and i needed a task to run in the backgound every 2 or 5 minutes.. and i collect the data and i display it when the app is opened.. so am using a sync task.... I'm having a bit of diffculty unerstanding how its used as every example is different..
and FYI am using a seperate .java file to runt he asynctask...
When we go through the android developers page this is the code we see...
They start with
Code:
private class DownloadFilesTask extends AsyncTask<URL, Integer, Long> {
1) whats the deal with the URL Integer Long ????? If i skip it what will happen???
next is this
Code:
protected void onProgressUpdate(Integer... progress) { setProgressPercent(progress[0]);
2) whats the integer doig there?? even if its not used in the function they put it... whats the deal??
3) Also how do we pass values like strings to a class??? i know about functions but the functions used in this class are like a group like so i cant exactly pass values to just one particular function...
Click to expand...
Click to collapse
Code:
public class async extends AsyncTask<Params , Progress , Result>{
}
here 'params' is the argument that is input to the object of the class...
for eg..
Code:
public class async extends AsyncTask<int , Progress , Result>{
}
then when you will call its object then it will like this.
Code:
public class async extends AsyncTask<int , Progress , Result>{
}
async c;
c.execute(10); // passed int value 10 to execute the async thread in the background...
it has 3 methods that should be implemented
Code:
class load extends AsyncTask<int, Void, Void>{
@Override
protected void onPostExecute(Void result) {
// TODO Auto-generated method stub
// all the ui updation is done here after doing the calculation...
}
@Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
// before the starting of calculation if ui needs to be adjusted then it is done here
}
@Override
protected Void doInBackground(int... arg0) {
// TODO Auto-generated method stub
// all calculation stuf is done here
}
}
IF U WANT SOME MORE HELP REGARDING ASYNC TASK THEN PLZZZ ASK AGAIN....
nvyaniv said:
Hi guys,
i've started making an app recently.. and i needed a task to run in the backgound every 2 or 5 minutes.. and i collect the data and i display it when the app is opened.. so am using a sync task.... I'm having a bit of diffculty unerstanding how its used as every example is different..
and FYI am using a seperate .java file to runt he asynctask...
When we go through the android developers page this is the code we see...
They start with
Code:
private class DownloadFilesTask extends AsyncTask<URL, Integer, Long> {
1) whats the deal with the URL Integer Long ????? If i skip it what will happen???
next is this
Code:
protected void onProgressUpdate(Integer... progress) { setProgressPercent(progress[0]);
2) whats the integer doig there?? even if its not used in the function they put it... whats the deal??
3) Also how do we pass values like strings to a class??? i know about functions but the functions used in this class are like a group like so i cant exactly pass values to just one particular function...
Click to expand...
Click to collapse
OK, so you're probably using it in a service, aren't you?
First of all, carefully read the tutorials here and here on vogella, to help you understand what it does.
1) these are the type of variables that are passed to the respective methods:
An asynchronous task is defined by 3 generic types, called Params, Progress and Result, and 4 steps, called onPreExecute, doInBackground, onProgressUpdate and onPostExecute
Click to expand...
Click to collapse
The Params get passed to the onPreExecute method, the Progress is the one you need to pass calling publishProgress and which is passed to onProgressUpdate. The result one should be returned by your doInBackground method and gets passed to the onPostExecute.
2) the Integer... Is actually an array of the corresponding object to int. Just ignore it and use the progress[0] as if it was a normal int.
3) set your Params variable to String so
AsyncTask <String, Integer, String> if you want to return a string as well
Ok i think i'm getting it... But when we say "Params , Progress , Result" its still a bit confusing..
we first hit pre execute then do iin BG then post execute... But the order in which the params are stated are not the same ...
when i give string first it always takes it for the during BG process... not for the pre execute...
For ex i say asymctask<int, string,void>
so my pre execute should get a int..
then my bg process should get a string..
the post execute should get nothing..
am i right???
nvyaniv said:
Ok i think i'm getting it... But when we say "Params , Progress , Result" its still a bit confusing..
we first hit pre execute then do iin BG then post execute... But the order in which the params are stated are not the same ...
when i give string first it always takes it for the during BG process... not for the pre execute...
For ex i say asymctask<int, string,void>
so my pre execute should get a int..
then my bg process should get a string..
the post execute should get nothing..
am i right???
Click to expand...
Click to collapse
Almost, the Progress variable is passed to the onProgressUpdate. This is something to indicate progress and publish on the UI Thread (for instance update a progress bar), usually an Integer. You can update the Progress from your doInBackground method by calling publishProgress, passing a Progress variable.
The point of this is that the doInBackground method runs in a seperate thread and all other methods run in the UI Thread! So you can't directly pass data between those, only with these values. Consider using a Bundle if you want to pass more than one variable!