This is my first post, so please be nice :)
I have a question and no one gave the answer in the post I've seen.
My app has a list and a button to open an activity, this activity creates a new item to show in the list of the previous activity when pressing the button Create.
How can I do this?
This is the code I made for the first button:
intent = new Intent(this.getBaseContext(), NewTestActivity.class);
this.finish();
startActivity(intent);
and this is the code to go back an refresh:
Intent intent = new Intent(getBaseContext(), TestListActivity.class);
startActivity(intent);
But the code to goback is useful, because the activity don't refresh.
I have to call the new activity in a diferent way? Or go back to previus activity in a diferent way? Or go back normally and refresh the activity when I'm back in the previus activity?
Well...this is all.
Sorry for my bad english and, if this question has been answered in another thread, give me the link to read, because I can't find it :)
PS: I started with android in December.
Thanks for your help.
When you are going to start new activity you shouldn't close a current one until you actually need this behaviour. (remove this.finish(); row from your code)
Also you shouldn't close an active activity manually until you actually need it. When the user presses the "back" button on the device Android pops the previous activity from the "back stack". Read once more Activity documentation.
According to your description you have a list of elements. So in order to refresh the list you need to update your dataset and notify the list about it by ListView.notifyDataSetChanged() method call.
Before getting to a real answer, I'd like to show some improvements to your code.
First, when creating an Intent (or when you need a context in general) from an Activity there is no need to call getBaseContext(), you can just use this:
intent = new Intent(this, NewTestActivity.class);
Second, android is good at handling Activities, you do not have to close your first activity manually with finish(). Android will automatically pause or stop your first activity and bring it back when you return to it.
Third, in your case you might want to use startActivityForResult() instead of startActivity() for reasons I will explain below.
This will make your code look like the following:
private static final int MY_REQUEST_CODE = 33487689; //put this at the top of your Activity-class, with any unique value.
intent = new Intent(this, NewTestActivity.class);
startActivityForResult(intent, MY_REQUEST_CODE);
Now, the startActivityForResult() starts an activity and waits for a result from that new Activity. When you call finsih() in the new Activity you will end up in the first Activitys onActivityResult()-method, with data supplied from the new Activty that is now closed:
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if(requestCode != MY_REQUEST_CODE) return; //We got a result from another request, so for this example we can return.
if(resultCode != RESULT_OK) return; //The user aborted the action, so we won't get any data.
//After the above if-statements we know that the activity that gives us a result was requested with the correct request code, and it's action was successful, we can begin extracting the data, which is in the data-intent:
Item item = (Item) data.getSerializableExtra("customData"); //casts the data object to the custom Item-class. This can be any class, as long as it is serializable. There are many other kinds of data that can be put into an intent, but for this example a serializable was used.
itemList.add(item); //This is the list that was specified in onCreate()
//If you use an Adapter, this is the place to call notifyDataSetChanged();
}
For this all to work, we need to do some things in the second Activity:
When the item has been created, we must set a result:
//We begin by packing our item in an Intent (the Item class is an example that is expected to implement Serializable)
Item theCreatedItem; //This is what was created in the activity
Intent data = new Intent();
data.putSerializable(theCreatedItem);
setResult(RESULT_OK, data);
finish();
This should return to the first Activitys onActivityResult()-method with the item, as explained above.
Related
Assuming I have three activities with Android Studio:
Act_A
Act_B
Act_C
The Act_A calls Act_B, and Act_B calls Act_C:
Intent intent = new Intent(Act_A.class,Act_B.class);
startActivity(intent);
...
Intent intent = new Intent(Act_B.class,Act_C.class);
startActivity(intent);
In Act_C a process is executed in which it should automatically be returned to Act_B, for which something similar is done:
Intent intent = new Intent(Act_C.class,Act_B.class);
startActivity(intent);
At this point, if the user presses the return button, it should be returned to Act_A, but it happens to be returned to Act_C, if you press once again the return button returns to Act_B.
My questions are:
Is there a way to "delete" the previous state so that it doesn't return to the previous activity or is there a way to modify it to return to the activity that I want?
The problem is that I have to return a value from Act_C to Act_B and I can not use finish(), something similar to the following:
In Act_C:
Intent intent = Act_B.newIntent(getActivity(),5);// return 5
startActivity(intent);
Thanks
You can call the finish() method of an Activity. It will get you back to Activity_B while you are in Activity_C
You can customize the back stack of your activity if you really need to, but in this case it seems that what you want is just to go back to B from C, instead of starting B from C.
In other words, in order to accomplish "In Act_C a process is executed in which it should automatically be returned to Act_B", do the following instead of startActivity():
super.onBackPressed();
This will return the app to Act_B. Then if the user presses the back button, they will return to Act_A as you specified.
Basically you can either call finish() on your activity, use the noHistory flag for the activity in your AndroidManifest.xml, or add the intent flag Intent.FLAG_ACTIVITY_NO_HISTORY to your intent.
This post should help you out: Removing an activity from the history stack
In Act_C a process is executed in which it should automatically be returned to Act_B
If you just want to return a value from a specific activity don't use startActivity(Intent), use startActivityForResult(Intent, int) and deal with the return values on the callback (OnActivityResult). Then overwrite the onFinish() method so that you can setResult() upon exit.
I can give you more context on this if you need.
I have an Online Ordering System from where users can complete the order in, at least, three steps. Each step below is a separate activity:
Make selection of a Plan
Select the Starting Date
Select Contents based on selected Plan in Step 1.
Now what I have done in step 1 is, once user clicks on a Plan and Order, below code runs onClick.
Intent intent = new Intent(context, SelectDate.class);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
Bundle extras = new Bundle();
extras.putString("pass_selected_meal_plan_id",mp_id_pass);
extras.putString("pass_selected_meal_name",mp_name_display);
intent.putExtras(extras);
context.startActivity(intent);
Toast.makeText(context, mp_name_display+" Selected",
Toast.LENGTH_SHORT).show();
No in the second Activity, I am asking the user to select the order starting date. That is also simple enough and have no issues in it. But the issue begins when I am trying to switch to the third activity.
Since my third activity content is depending on the Plan selection made in the first activity, therefore I have to transfer the selected ID to the third activity. I have it in Extra Bundle in second activity as "pass_selected_meal_plan_id".
The way I am loading the third activity is also crucial. There are two possible ways to start the third activity. First is very simple by putting onClick on the next button. I assume that it will be very simple to transfer the required selection as well. But in this case, as far as I know being a beginner in Android App Development, I will have to give a button to click and load content based on the selected Plan.
The second way is what I want to use. I am running an AsyncTask in the second activity onClick Next. It is working perfectly fine. The only this is I am unable to getExtras in onPostExecute from the previous Activity, i.e. first activity.
I am open to even using Global Variables, but don't really know how to do. Knowing what Global Variables are, I am not too keen to use them instead.
Here is my onPostExecute code:
#Override
protected void onPostExecute(String result) {
Intent intent = new Intent(ctx, SelectMeals.class);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
Bundle extras = new Bundle();
//Instead of "1" I want the value from previous Activity, which already available in Extras from previous Activity
extras.putString("pass_selected_meal_plan_id", "1");
//This is the second value I want to be transferred from first activity to the third activity
extras.putString("pass_selected_meal_name","Test");
intent.putExtras(extras);
ctx.startActivity(intent);
}
Would really appreciate if anyone can help.
You can use below code
In your second activity
// declare global variables
String id;
String name;
Use below code inside onCreate
Bundle bundle = getIntent().getExtras();
//Extract the data…
id = bundle.getString("pass_selected_meal_plan_id");
name = bundle.getString("pass_selected_meal_name");
Now in your Asynctask, write the code below before launching 3rd activity.
#Override
protected void onPostExecute(String result) {
Intent intent = new Intent(ctx, SelectMeals.class);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
Bundle extras = new Bundle();
extras.putString("pass_selected_meal_plan_id",id); // first activity data
extras.putString("pass_selected_meal_name",name); // first activity data
intent.putExtras(extras);
ctx.startActivity(intent);
}
Finally, you can get these values in third activity.
One important point I would like to highlight is that avoid using generic variable names, e.g. id. It is used just for reference in this answer but it is not a good idea. One obvious problem you may face doing so is with Refactor > Rename. It will change even the #+id in XML files.
I have a problem with my Login screen. When it's started, I check for network connection, and if it's disabled, I want to show NoNetworkActivity. And the same for every other screen: when Activity is launched, I check network connection and navigate to NoNetworkActivity is needed. When navigating, I want to save the Intent which launched this previous activity and finish it to disable the Back button redirection when on NoNetworkActivity. So, when connection is restored, I want to launch that intent and get actual state of the app before this error:
LoginActivity
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
if (!App.getInstance().isNetworkConnected()) {
Intent noNetwork = new Intent(this, NoNetworkActivity.class);
noNetwork.putExtra(NoNetworkActivity.EXTRA_FAILED_INTENT, getIntent());
startActivity(noNetwork);
finish();
}
...
NoNetworkActivity
private void checkNetworkConnection() {
mCheckButton.setVisibility(View.INVISIBLE);
mProgressBar.setVisibility(View.VISIBLE);
if (App.getInstance().isNetworkConnected()) {
Intent failedIntent = getIntent().getParcelableExtra(EXTRA_FAILED_INTENT);
startActivity(failedIntent);
finish();
} else {
mCheckButton.setVisibility(View.VISIBLE);
mProgressBar.setVisibility(View.INVISIBLE);
App.toast("Connection failed");
}
}
And it's getting strange: startActivity(failedIntent) does NOTHING. I've tried to remove finish() from next line, and NoNetworkActivity just stays on top without anything happening.
And one more thing. You can suggest passing Activity actual class names instead of intents, but I realy need Intent. That's because I'm using a lot of starting actions for every activity and a bunch of extras.
Thanks in advance for any help. Cheers!
Very bad approach. Don't use it.
First, you don't need to finish previous activity just to disable Back action. You can override onBackPressed().
Second, you don't need to start parent activity again. Just call a new activity with startActivityForResult(); and override onActivityResult() callback.
Third, but most important. Why do you want to call a new activity just to show 'No Network' message? And what if network won't be re-established? Just create isNetworkEnabled() method and call it when user attempts to get data from the Internet, before sending actual request to server. If no network - notify a user with an alert or toast.
I suggest you use fragments instead of activities first of all.
Using fragments you can set retainInstance(true);
To disable coming back from an activity to the previous :
1)call finish() on that activity
2)
Intent i = new Intent();
i.setClass(this, MyActivity.class);
i.addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP);
startActivity(i);`
It works with an explicit Intent.
In LoginActivity substitute:
noNetwork.putExtra(NoNetworkActivity.EXTRA_FAILED_INTENT, getIntent());
with:
noNetwork.putExtra(NoNetworkActivity.EXTRA_FAILED_INTENT, new Intent(this, LoginActivity.class));
Btw, Alexander Zhak has some good points in his answer
There are a lot of questions out there on similar topics, but after searching around I haven't found one that matches my issue.
I know about starting intents for result, and overriding onActivityResult() to handle these intents, but for some reason, I'm having issues when I'm coming back from activity b to activity a. So, for example, in the last of 3 activities (AddDirections class) I start in my project, I call this method to return back to the previous activity:
public void finish(View v){
Intent intent = new Intent(getApplicationContext(), AddIngredients.class);
intent.putExtra(Home.RECIPE_INTENT, (Parcelable)recipe);
intent.putExtra(Home.RECIPE_ID_INTENT, recipe.getId());
setResult(RESULT_OK, intent);
finish();
}
In the AddIngredients class, I have this method:
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data){
super.onActivityResult(requestCode, resultCode, data);
if(resultCode == RESULT_OK && requestCode == DIRECTIONS_REQUEST){
Intent intent = new Intent(getApplicationContext(), NameRecipe.class);
Recipe recipe = data.getParcelableExtra(Home.RECIPE_INTENT);
intent.putExtra(Home.RECIPE_INTENT, (Parcelable)recipe);
setResult(RESULT_OK, intent);
finish();
}
}
This should accept the returned result from the AddDirections class, and pass it off to NameRecipe, where I have the exact same method (Except for in the new Intent method it says Home.class). In the Home class, I have basically the same method again to receive the intent as it backs all the way out of the app.
Now, I will say that this works if I go straight through the steps from beginning to end. But if I use the up navigation to go the current activity's parent activity, then it messes everything up. Then when I click finish in the final step it messes up the resultCodes that I set for each intent. I make sure to explicitly set the correct result to RESULT_OK (which equals 1) but then for some reason, sometimes it changes what I've set to be the resultCode to be 0 instead.
Here's what I do in an activity if the user clicks the up navigation:
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
Intent intent = NavUtils.getParentActivityIntent(this);
intent.putExtra(Home.RECIPE_INTENT, (Parcelable)recipe);
setResult(RESULT_OK, intent);
NavUtils.navigateUpTo(this, intent);
finish(); //Have tried with and without this
return true;
}
return super.onOptionsItemSelected(item);
}
Like I said, I've searched for a lot of reasons why the resultCode gets overwritten after using the up navigation, but I haven't found a single reason why.
Any help would be greatly appreciated.
It looks like the underlying question is really how do I navigate between multiple activities through the stack using the up navigation that is built in. I am wondering if the project is setup correctly for this type of navigation. From the android developer resources, up navigation from google, you have to setup the navigation buttons with a parent activity. Then the application can traverse between the different activities. From what it looks like this should allow A->B B->C c->D and back to A if needed. I would also add in a button that would allow a direct path back to A if the user so chooses.
If you have more information on what you are trying to accomplish between activities whether it is data passed back and forth or just returning to the previous activity that would be helpful. Hopefully the link will help your issue with this.
your problem seems to be the NavUp, this util class tends to clear everything to navigate to the parent including your resultCode and the instance of the activity, resulting in a Canceled result (if started for result) to a new instance of the parent activity, in order to fix that a quick fix would be to declare android:launchMode="singleTop" in your manifest, but I wouldn't recommend to use that unless you are 100% that you want that, instead I would go into my navigator class, or my method for navigate and overwrite that specific navigation to something like:
Intent parentActivityIntent = NavUtils.getParentActivityIntent(this);
parentActivityIntent.setFlags(
Intent.FLAG_ACTIVITY_SINGLE_TOP | Intent.FLAG_ACTIVITY_CLEAR_TOP
);
NavUtils.navigateUpTo(this, parentActivityIntent);
Hope this helps!!
Sorry for the late answer :p
if by 'up navigation' you mean back key pressed then you need to override a function
#Override
public void onBackPressed() {
// TODO Auto-generated method stub
super.onBackPressed();
}
if from what it seems to be you are trying to get back when clicking an item from the Options Menu to your parent activity directly then i think you will need to go back step by step as at this moment there is already an activity running and waiting for a result so when you go directly to home activity its already waiting an answer from activity B and not activity C i hope i explained it right :)
I am implementing a simple app. I need to start an activity based on the state of the Activity. Lets take i am using a button to start the activity.
1. If the activity is not started, I need to start XYZ activity.
2. If the XYZ activity is on focus, then i need to close the activity on the button press.
3. If the XYZ activity is not in focus (like onPause) state then, I need to change the button state.
Can you please help me in the flags that i need to use for starting the intent.
Is it possible to get the state of activity before I start that activity?
Try this
Intent intent = new Intent(currentActivity.this, callingActivity.class);
startActivity(intent);
You can use intent like this to call an activity
The button press will need to be captured by each activity separately, so just code the different responses into each different activity.
First off create a MAIN.java activity that is going to house your other activities. Like others have said you're going to have to code the button captures yourself because that should be common sense if you're trying to deal with intents. When you get that together though, you can start a new activity through intent like so:
// allocate new intent, initialized to the activity you wish to launch
Intent i = new Intent(this, ActivityToBeLaunched.class);
// put information into intent
i.putExtras("KeyName", value); // where "KeyName" is simply a reference string
// and 'value' can be anything from boolean - string.
// launch activity and wait for response
startActivityForResult(i, REQUEST_CODE);
Then within your ActivityToBeLaunched.java class you'll have an oncreate that will pull information from the intent like such:
// get intent
Intent i = this.getIntent();
// get information from intent
booleanVariable = i.getExtras().getBoolean("KeyName");
When you're done with this activity simply use;
// create intent
Intent i = new Intent();
// put information into result to send back to parent
i.putExtras("KeyName", value);
// set the result to be returned
setResult(i, ResultCode);
// finish child, return to parent with results
finish();