Develop Reference

How to pass the class of activity to the intent which this activity has opened?

I am working on a project where I have come over a problem. My main activity is a list of sites I need to parse. I am making a preferences window. Inside of it I can choose which sites I want to see in the main activity and which I don't (checkboxes). I also have a couple more preferences (show the images or not) for other activities. The preference activity is accessible from any other activity through the NavigationDrawer. I haven't found a good answer on how to refresh the main page correctly so I have come to a conclusion that I need to restart the activity when I press the back button. The problem is I want to restart the activity that has opened the Preference Activity. Is there a way to pass the class through the intent so that I know what activity I want to open?

create a static activity in preference activity, and assign current activity to it before starting preference activity. and after finishing preference activity refresh current activity
preference Activity
public class PreferenceAtivity extends Activity {
public static Activity currentActivity;
pubic void save(View v) {
finish();
currentActivity.recreate();
}
}
another activity
public class AnotherAtivity extends Activity {
#Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == R.id.preference) {
PreferenceActivity.currentActivity = this;
startAtivity(new Intent(this, PreferenceActivity.class);
return true;
}
return super.onOptionsItemSelected(item);
}
}

How to call (and use) onOptionsItemSelected from MainActivity in other classes

I'm making my very first Android application but I ran into a problem.
I have over 8 different classes which all use the same actionbar.
Now in place of calling the method in every different class (and having a lot of double code) I would like to call the method of the main class in my other classes.
This is a part of my code for the onOptionsItemSelected in main.java
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle presses on the action bar items
switch (item.getItemId()) {
case R.id.actionbar_new_income:
Intent newIncome = new Intent(this, NewIncome.class);
this.startActivity(newIncome);
return true;
}
}
Now I was wondering how I could call the method in another class (newIncome.java)
I have this so far, but it keeps saying I need to add arguments. And I ofcourse need to be able to detect which menuitem is clicked..
MainActivity main = new MainActivity();
main.onOptionsItemSelected();
Any help please?
Thanks!

You should not do this. If you have common code then put it in a class (not an activity) that is accessible by any activity that needs it.
You will still have some duplication but this is normal.
A good way of reducing activity launch code is to add a static method to each activity that you can call which launches the activity it is in.
E.g in your NewIncome Activity you could have
Public static void Launch(Context c) {
Intent newIncome = new Intent(c, NewIncome.class);
C.startActivity(newIncome);
}
You could then launch this activity from any other activity just by calling
NewIncome.Launch(this);
If required you can add parameters to the method and then add Extras to the Activity using these parameters.

You can do it like the following example if your menu entries are totally independent of the activity in which they are contained:
In each activity
#Override
public boolean onOptionsItemSelected(MenuItem item) {
return CommonClass.HandleMenu(this, item.getItemId());
}
In a common class
public class CommonClass {
public boolean HandleMenu (Context c, int MenuEntry) {
switch (MenuEntry) {
case R.id.actionbar_new_income:
NewIncome.Launch(c);
etc....
...
}
}

If your 8 classes are activities you may define a base activity with the onOptionsItemSelected which is the one where you put the elements in the actionbar you want. Then make the other activities derive from it.

Remove an activity from the stack

I have three activities ActivityA, ActivityB, ActivityC.
Suppose in ActivityA, there is some code like...
if(someCondition()){
gotoActivityB();
}
else{
gotoActivityC();
}
Now, If user goes to ActivityB, ActivityA should not be finished.
If he goes to ActivityC, it should be finished.
Adding noHistory in manifest file doesn't work.
Also, finish()in if condition doesn't work, As there are many activities after ActivityC in which ActivityA should be in background.
I don't want to call startActivity(context,ActivityA.class)in those activities onBackPressed() because, it will again execute code of onCreate() in ActivityA.
So, is there a way, where i can remove ActivityA from the stack when user presses back button in ActivityB?
may be something like this:?
ActivityB.this.finish();
ActivityA.finish(); //some code to finish ActivityA

Okay, here is one way you can accomplish your goal. You will need to pass around the Activity context to wherever you need it in order to call finish() on it. I used the Application class to do this. I only used two classes to do it for the sake of time, but it should work just fine for your purposes. Here is how I did it:
This is the first class. It is the Activity that we want to close from another Activity.
public class MainActivity extends Activity implements OnClickListener {
private Button button;
// application instance
private MainApplication mainApplication;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mainApplication = (MainApplication) getApplicationContext();
// set the Activity's context for later usage. Doing this determines which
// Activity can be closed from another Activity.
mainApplication.setActivityContext(this);
button = (Button) findViewById(R.id.button1);
button.setOnClickListener(this);
}
public void onClick(View v) {
switch (v.getId()) {
case R.id.button1:
Intent i = new Intent(this, SecondActivity.class);
startActivity(i);
break;
}
}
}
This is the Second Activity. Exiting out of it will also cause finish() to be called on the first class:
public class SecondActivity extends Activity {
private Activity activityContext;
private MainApplication mainApplication;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.second_activity_layout);
mainApplication = (MainApplication) getApplicationContext();
// get the Activity context you stored in the MainApplication class
// so you can call finish on it.
activityContext = mainApplication.getActivityContext();
}
#Override
protected void onPause() {
super.onPause();
// closes your defined Activity. If you press the back button you will find
// that you exit right out of the app as the other Activity gets popped off
// the stack.
activityContext.finish();
}
}
And the Application class:
public class MainApplication extends Application {
private Activity activityContext;
public Activity getActivityContext() {
return activityContext;
}
public void setActivityContext(Activity activityContext) {
this.activityContext = activityContext;
}
}
And of course make sure to declare your MainApplication class in the AndroidManifest:
<application
android:name=".MainApplication"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
This is a sort of hacky way to do this. There may be better ways. But regardless, you have to pass around the context of the Activity that you want to call finish() on. Then you can close it from anywhere.

Hi you can finish your activity in current activity itself based on the condition. or use StartActivityforResult based on the result you can finish your activity.
hope this will help you.

You can try this in another way, like i do.
Create a static instance variable of the activity in the beginning.
private static Activity1 thisAct = null; // Activity1 is name of class
Now initialize this variable in onCreate() method
thisAct = this;
Create a static method which will finish this activity
public static void finishActivity()
{
thisAct.finish();
}

While going to Activity C, clear the FLAG :
Intent cIntent = new Intent(view.getContext(), cActivity.class).setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(cIntent);

onBackPressed() behaviour with ActivityGroups

Quick question: I have an activitygroup. Within that Activitygroup I have an activity. If I press back while inside this activity. the onBackPressed method of the activity is called - Not the Activitygroups onBackPressed - Why is that ?
EDIT: Got my answer but the problem remains. Here follows code and explanation of my original issue:
I am using ActivityGroups within a TabHost and as such have been "forced" into overriding onBackPressed. I can navigate through my application without issue by pressing back on my phone and by pressing the tabs on my tabhost. But I cannot interact with the interface after pressing Back.
Once I press one of the tabs on the tabhost again I can interact with everything like normal. Why is this happening? Do I need to override onResume?
Relevant code
SettingsActivityGroup :
public class SettingsActivityGroup extends ActivityGroup
{
// Keep this in a static variable to make it accessible for all the nested activities, lets them manipulate the view
public static SettingsActivityGroup group;
// Need to keep track of the history if you want the back-button to work properly, don't use this if your activities requires a lot of memory.
private ArrayList<View> history;
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
// Allocate history
this.history = new ArrayList<View>();
// Set group
group = this;
// Start root (first) activity
Intent myIntent = new Intent(this, SettingsActivity.class); // Change to the first activity of your ActivityGroup
myIntent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
ReplaceView("SettingsActivity", myIntent);
}
/*
* Replace the activity with a new activity and add previous one to history
*/
public void ReplaceView(String pId, Intent pIntent)
{
Window window = getLocalActivityManager().startActivity(pId, pIntent);
View view = (window != null) ? window.getDecorView() : null;
// Add the old activity to the history
history.add(view);
// Set content view to new activity
setContentView(view);
}
/*
* Go back from previous activity or close application if there is no previous activity
*/
public void back()
{
if(history.size() > 1)
{
// Remove previous activity from history
history.remove(history.size()-1);
// Go to activity
View view = history.get(history.size() - 1);
Activity activity = (Activity) view.getContext();
// "Hack" used to determine when going back from a previous activity
// This is not necessary, if you don't need to redraw an activity when going back
activity.onWindowFocusChanged(true);
// Set content view to new activity
setContentView(view);
}
else
{
// Close the application
finish();
}
}
/*
* Overwrite the back button
*/
#Override
public void onBackPressed()
{
// Go one back, if the history is not empty
// If history is empty, close the application
SettingsActivityGroup.group.back();
return;
}
}
Arbitrary child of SettingsActivityGroup(CallForwardActivity)
public class CallForwardActivity extends ListActivity
{
....
#Override
public void onBackPressed()
{
// Go one back, if the history is not empty
// If history is empty, close the application
SettingsActivityGroup.group.back();
return;
}
}

Because I believe calling onBackPressed() of the currently selected activity is the desired behavior.
It's also worth noting that ActivityGroup is deprecated, but I assume you are coding for <3.0 and don't fancy working with the support libraries.
Regarding your edited question:
Another question on this site cites this article as a good ActivityGroup example, and I would agree http://ericharlow.blogspot.com/2010/09/experience-multiple-android-activities.html
This example just calls finish() on the current activity when back is pressed, and lets the os restart the previous activity, which is simpler than what you are doing, and will hopefully work! You can just call getParent() in your child activities too to avoid using that static reference (just seems easier to read to me that way!).

How to call a method from one tab to another?

i have a tabActivity that hold 3 tabs.
from one tab i want to open another tab and run a method that refresh the data.
i use this method to switch tabs
public void switchTabInActivity(int indexTabToSwitchTo) {
MyTabsActivity ParentActivity;
ParentActivity = (MyTabsActivity) this.getParent();
ParentActivity.switchTab(indexTabToSwitchTo);
}
to open the tab but i cant' call the method.
any ideas?

According to me, I believe what you are doing here is correct, but still you are not doing the entire flow. Let me explain,
Calling the above method will redirect you to that particular tab. But what you actually have to do is to execute some method in that class. But were are you calling that method.
Consider a Activity with onCreate(),
you could have called that method in your onCreate(). But now when you execute your
public void switchTabInActivity(int indexTabToSwitchTo) {
MyTabsActivity ParentActivity;
ParentActivity = (MyTabsActivity) this.getParent();
ParentActivity.switchTab(indexTabToSwitchTo);
}
method, this will call the onResume() of that activity. So my suggestion would be to override the onResume method of your particular activity which has that method..

you can simply create a static method which can be easily call by using ClassName.methodName();
see example,
public class myAnotherClass
{
public static void accessFromAnotherClass()
{
System.out.println ( "I am accessed publically" );
}
}
// Now Accessing above class method from another class file
public class myFirstClass
{
private void myClassMethod()
{
myAnotherClass.accessFromAnotherClass(); // called from another class. in your case , another tab.
}
}