DialogFragment

Class Overview

A fragment that displays a dialog window, floating on top of its activity's window. This fragment contains a Dialog object, which it displays as appropriate based on the fragment's state. Control of the dialog (deciding when to show, hide, dismiss it) should be done through the API here, not with direct calls on the dialog.

Implementations should override this class and implement onCreateView(LayoutInflater, ViewGroup, Bundle) to supply the content of the dialog. Alternatively, they can override onCreateDialog(Bundle) to create an entirely custom dialog, such as an AlertDialog, with its own content.

Topics covered here:

1. Lifecycle
2. Basic Dialog
3. Alert Dialog
4. Selecting Between Dialog or Embedding

Lifecycle

DialogFragment does various things to keep the fragment's lifecycle driving it, instead of the Dialog. Note that dialogs are generally autonomous entities -- they are their own window, receiving their own input events, and often deciding on their own when to disappear (by receiving a back key event or the user clicking on a button).

DialogFragment needs to ensure that what is happening with the Fragment and Dialog states remains consistent. To do this, it watches for dismiss events from the dialog and takes care of removing its own state when they happen. This means you should use show(FragmentManager, String) or show(FragmentTransaction, String) to add an instance of DialogFragment to your UI, as these keep track of how DialogFragment should remove itself when the dialog is dismissed.

Basic Dialog

The simplest use of DialogFragment is as a floating container for the fragment's view hierarchy. A simple implementation may look like this:

public static class MyDialogFragment extends DialogFragment {
    int mNum;

    /**
     * Create a new instance of MyDialogFragment, providing "num"
     * as an argument.
     */
    static MyDialogFragment newInstance(int num) {
        MyDialogFragment f = new MyDialogFragment();

        // Supply num input as an argument.
        Bundle args = new Bundle();
        args.putInt("num", num);
        f.setArguments(args);

        return f;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mNum = getArguments().getInt("num");

        // Pick a style based on the num.
        int style = DialogFragment.STYLE_NORMAL, theme = 0;
        switch ((mNum-1)%6) {
            case 1: style = DialogFragment.STYLE_NO_TITLE; break;
            case 2: style = DialogFragment.STYLE_NO_FRAME; break;
            case 3: style = DialogFragment.STYLE_NO_INPUT; break;
            case 4: style = DialogFragment.STYLE_NORMAL; break;
            case 5: style = DialogFragment.STYLE_NORMAL; break;
            case 6: style = DialogFragment.STYLE_NO_TITLE; break;
            case 7: style = DialogFragment.STYLE_NO_FRAME; break;
            case 8: style = DialogFragment.STYLE_NORMAL; break;
        }
        switch ((mNum-1)%6) {
            case 4: theme = android.R.style.Theme_Holo; break;
            case 5: theme = android.R.style.Theme_Holo_Light_Dialog; break;
            case 6: theme = android.R.style.Theme_Holo_Light; break;
            case 7: theme = android.R.style.Theme_Holo_Light_Panel; break;
            case 8: theme = android.R.style.Theme_Holo_Light; break;
        }
        setStyle(style, theme);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.fragment_dialog, container, false);
        View tv = v.findViewById(R.id.text);
        ((TextView)tv).setText("Dialog #" + mNum + ": using style "
                + getNameForNum(mNum));

        // Watch for button clicks.
        Button button = (Button)v.findViewById(R.id.show);
        button.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {
                // When button is clicked, call up to owning activity.
                ((FragmentDialog)getActivity()).showDialog();
            }
        });

        return v;
    }
}

An example showDialog() method on the Activity could be:

void showDialog() {
    mStackLevel++;

    // DialogFragment.show() will take care of adding the fragment
    // in a transaction.  We also want to remove any currently showing
    // dialog, so make our own transaction and take care of that here.
    FragmentTransaction ft = getFragmentManager().beginTransaction();
    Fragment prev = getFragmentManager().findFragmentByTag("dialog");
    if (prev != null) {
        ft.remove(prev);
    }
    ft.addToBackStack(null);

    // Create and show the dialog.
    DialogFragment newFragment = MyDialogFragment.newInstance(mStackLevel);
    newFragment.show(ft, "dialog");
}

This removes any currently shown dialog, creates a new DialogFragment with an argument, and shows it as a new state on the back stack. When the transaction is popped, the current DialogFragment and its Dialog will be destroyed, and the previous one (if any) re-shown. Note that in this case DialogFragment will take care of popping the transaction of the Dialog is dismissed separately from it.

Alert Dialog

Instead of (or in addition to) implementing onCreateView(LayoutInflater, ViewGroup, Bundle) to generate the view hierarchy inside of a dialog, you may implement onCreateDialog(Bundle) to create your own custom Dialog object.

This is most useful for creating an AlertDialog, allowing you to display standard alerts to the user that are managed by a fragment. A simple example implementation of this is:

public static class MyAlertDialogFragment extends DialogFragment {

    public static MyAlertDialogFragment newInstance(int title) {
        MyAlertDialogFragment frag = new MyAlertDialogFragment();
        Bundle args = new Bundle();
        args.putInt("title", title);
        frag.setArguments(args);
        return frag;
    }

    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        int title = getArguments().getInt("title");

        return new AlertDialog.Builder(getActivity())
                .setIcon(R.drawable.alert_dialog_icon)
                .setTitle(title)
                .setPositiveButton(R.string.alert_dialog_ok,
                    new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int whichButton) {
                            ((FragmentAlertDialog)getActivity()).doPositiveClick();
                        }
                    }
                )
                .setNegativeButton(R.string.alert_dialog_cancel,
                    new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int whichButton) {
                            ((FragmentAlertDialog)getActivity()).doNegativeClick();
                        }
                    }
                )
                .create();
    }
}

The activity creating this fragment may have the following methods to show the dialog and receive results from it:

void showDialog() {
    DialogFragment newFragment = MyAlertDialogFragment.newInstance(
            R.string.alert_dialog_two_buttons_title);
    newFragment.show(getFragmentManager(), "dialog");
}

public void doPositiveClick() {
    // Do stuff here.
    Log.i("FragmentAlertDialog", "Positive click!");
}

public void doNegativeClick() {
    // Do stuff here.
    Log.i("FragmentAlertDialog", "Negative click!");
}

Note that in this case the fragment is not placed on the back stack, it is just added as an indefinitely running fragment. Because dialogs normally are modal, this will still operate as a back stack, since the dialog will capture user input until it is dismissed. When it is dismissed, DialogFragment will take care of removing itself from its fragment manager.

Selecting Between Dialog or Embedding

A DialogFragment can still optionally be used as a normal fragment, if desired. This is useful if you have a fragment that in some cases should be shown as a dialog and others embedded in a larger UI. This behavior will normally be automatically selected for you based on how you are using the fragment, but can be customized with setShowsDialog(boolean).

For example, here is a simple dialog fragment:

public static class MyDialogFragment extends DialogFragment {
    static MyDialogFragment newInstance() {
        return new MyDialogFragment();
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.hello_world, container, false);
        View tv = v.findViewById(R.id.text);
        ((TextView)tv).setText("This is an instance of MyDialogFragment");
        return v;
    }
}

An instance of this fragment can be created and shown as a dialog:

void showDialog() {
    // Create the fragment and show it as a dialog.
    DialogFragment newFragment = MyDialogFragment.newInstance();
    newFragment.show(getFragmentManager(), "dialog");
}

It can also be added as content in a view hierarchy:

FragmentTransaction ft = getFragmentManager().beginTransaction();
DialogFragment newFragment = MyDialogFragment.newInstance();
ft.add(R.id.embedded, newFragment);
ft.commit();

Summary

[Expand] Inherited Constants

From interface android.content.ComponentCallbacks2 int TRIM_MEMORY_BACKGROUND Level for onTrimMemory(int): the process has gone on to the LRU list. int TRIM_MEMORY_COMPLETE Level for onTrimMemory(int): the process is nearing the end of the background LRU list, and if more memory isn't found soon it will be killed. int TRIM_MEMORY_MODERATE Level for onTrimMemory(int): the process is around the middle of the background LRU list; freeing memory can help the system keep other processes running later in the list for better overall performance. int TRIM_MEMORY_RUNNING_CRITICAL Level for onTrimMemory(int): the process is not an expendable background process, but the device is running extremely low on memory and is about to not be able to keep any background processes running. int TRIM_MEMORY_RUNNING_LOW Level for onTrimMemory(int): the process is not an expendable background process, but the device is running low on memory. int TRIM_MEMORY_RUNNING_MODERATE Level for onTrimMemory(int): the process is not an expendable background process, but the device is running moderately low on memory. int TRIM_MEMORY_UI_HIDDEN Level for onTrimMemory(int): the process had been showing a user interface, and is no longer doing so.

[Expand] Inherited Methods
From class android.app.Fragment void dump(String prefix, FileDescriptor fd, PrintWriter writer, String[] args) Print the Fragments's state into the given stream. final boolean equals(Object o) Subclasses can not override equals(). final Activity getActivity() Return the Activity this fragment is currently associated with. final Bundle getArguments() Return the arguments supplied when the fragment was instantiated, if any. final FragmentManager getChildFragmentManager() Return a private FragmentManager for placing and managing Fragments inside of this Fragment. final FragmentManager getFragmentManager() Return the FragmentManager for interacting with fragments associated with this fragment's activity. final int getId() Return the identifier this fragment is known by. LoaderManager getLoaderManager() Return the LoaderManager for this fragment, creating it if needed. final Fragment getParentFragment() Returns the parent Fragment containing this Fragment. final Resources getResources() Return getActivity().getResources(). final boolean getRetainInstance() final String getString(int resId) Return a localized string from the application's package's default string table. final String getString(int resId, Object... formatArgs) Return a localized formatted string from the application's package's default string table, substituting the format arguments as defined in Formatter and format(String, Object...). final String getTag() Get the tag name of the fragment, if specified. final Fragment getTargetFragment() Return the target fragment set by setTargetFragment(Fragment, int). final int getTargetRequestCode() Return the target request code set by setTargetFragment(Fragment, int). final CharSequence getText(int resId) Return a localized, styled CharSequence from the application's package's default string table. boolean getUserVisibleHint() View getView() Get the root view for the fragment's layout (the one returned by onCreateView(LayoutInflater, ViewGroup, Bundle)), if provided. final int hashCode() Subclasses can not override hashCode(). static Fragment instantiate(Context context, String fname) Like instantiate(Context, String, Bundle) but with a null argument Bundle. static Fragment instantiate(Context context, String fname, Bundle args) Create a new instance of a Fragment with the given class name. final boolean isAdded() Return true if the fragment is currently added to its activity. final boolean isDetached() Return true if the fragment has been explicitly detached from the UI. final boolean isHidden() Return true if the fragment has been hidden. final boolean isInLayout() Return true if the layout is included as part of an activity view hierarchy via the <fragment> tag. final boolean isRemoving() Return true if this fragment is currently being removed from its activity. final boolean isResumed() Return true if the fragment is in the resumed state. final boolean isVisible() Return true if the fragment is currently visible to the user. void onActivityCreated(Bundle savedInstanceState) Called when the fragment's activity has been created and this fragment's view hierarchy instantiated. void onActivityResult(int requestCode, int resultCode, Intent data) Receive the result from a previous call to startActivityForResult(Intent, int). void onAttach(Activity activity) Called when a fragment is first attached to its activity. void onConfigurationChanged(Configuration newConfig) Called by the system when the device configuration changes while your component is running. boolean onContextItemSelected(MenuItem item) This hook is called whenever an item in a context menu is selected. void onCreate(Bundle savedInstanceState) Called to do initial creation of a fragment. Animator onCreateAnimator(int transit, boolean enter, int nextAnim) Called when a fragment loads an animation. void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) Called when a context menu for the view is about to be shown. void onCreateOptionsMenu(Menu menu, MenuInflater inflater) Initialize the contents of the Activity's standard options menu. View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) Called to have the fragment instantiate its user interface view. void onDestroy() Called when the fragment is no longer in use. void onDestroyOptionsMenu() Called when this fragment's option menu items are no longer being included in the overall options menu. void onDestroyView() Called when the view previously created by onCreateView(LayoutInflater, ViewGroup, Bundle) has been detached from the fragment. void onDetach() Called when the fragment is no longer attached to its activity. void onHiddenChanged(boolean hidden) Called when the hidden state (as returned by isHidden() of the fragment has changed. void onInflate(AttributeSet attrs, Bundle savedInstanceState) This method was deprecated in API level 12. Use onInflate(Activity, AttributeSet, Bundle) instead. void onInflate(Activity activity, AttributeSet attrs, Bundle savedInstanceState) Called when a fragment is being created as part of a view layout inflation, typically from setting the content view of an activity. void onLowMemory() This is called when the overall system is running low on memory, and actively running processes should trim their memory usage. boolean onOptionsItemSelected(MenuItem item) This hook is called whenever an item in your options menu is selected. void onOptionsMenuClosed(Menu menu) This hook is called whenever the options menu is being closed (either by the user canceling the menu with the back/menu button, or when an item is selected). void onPause() Called when the Fragment is no longer resumed. void onPrepareOptionsMenu(Menu menu) Prepare the Screen's standard options menu to be displayed. void onResume() Called when the fragment is visible to the user and actively running. void onSaveInstanceState(Bundle outState) Called to ask the fragment to save its current dynamic state, so it can later be reconstructed in a new instance of its process is restarted. void onStart() Called when the Fragment is visible to the user. void onStop() Called when the Fragment is no longer started. void onTrimMemory(int level) Called when the operating system has determined that it is a good time for a process to trim unneeded memory from its process. void onViewCreated(View view, Bundle savedInstanceState) Called immediately after onCreateView(LayoutInflater, ViewGroup, Bundle) has returned, but before any saved state has been restored in to the view. void onViewStateRestored(Bundle savedInstanceState) Called when all saved state has been restored into the view hierarchy of the fragment. void registerForContextMenu(View view) Registers a context menu to be shown for the given view (multiple views can show the context menu). void setArguments(Bundle args) Supply the construction arguments for this fragment. void setHasOptionsMenu(boolean hasMenu) Report that this fragment would like to participate in populating the options menu by receiving a call to onCreateOptionsMenu(Menu, MenuInflater) and related methods. void setInitialSavedState(Fragment.SavedState state) Set the initial saved state that this Fragment should restore itself from when first being constructed, as returned by FragmentManager.saveFragmentInstanceState. void setMenuVisibility(boolean menuVisible) Set a hint for whether this fragment's menu should be visible. void setRetainInstance(boolean retain) Control whether a fragment instance is retained across Activity re-creation (such as from a configuration change). void setTargetFragment(Fragment fragment, int requestCode) Optional target for this fragment. void setUserVisibleHint(boolean isVisibleToUser) Set a hint to the system about whether this fragment's UI is currently visible to the user. void startActivity(Intent intent) Call startActivity(Intent) from the fragment's containing Activity. void startActivity(Intent intent, Bundle options) Call startActivity(Intent, Bundle) from the fragment's containing Activity. void startActivityForResult(Intent intent, int requestCode) Call startActivityForResult(Intent, int) from the fragment's containing Activity. void startActivityForResult(Intent intent, int requestCode, Bundle options) Call startActivityForResult(Intent, int, Bundle) from the fragment's containing Activity. String toString() Returns a string containing a concise, human-readable description of this object. void unregisterForContextMenu(View view) Prevents a context menu to be shown for the given view.
From class java.lang.Object Object clone() Creates and returns a copy of this Object. boolean equals(Object o) Compares this instance with the specified object and indicates if they are equal. void finalize() Invoked when the garbage collector has detected that this instance is no longer reachable. final Class<?> getClass() Returns the unique instance of Class that represents this object's class. int hashCode() Returns an integer hash code for this object. final void notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up. final void notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up. String toString() Returns a string containing a concise, human-readable description of this object. final void wait() Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object. final void wait(long millis, int nanos) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires. final void wait(long millis) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
From interface android.content.ComponentCallbacks abstract void onConfigurationChanged(Configuration newConfig) Called by the system when the device configuration changes while your component is running. abstract void onLowMemory() This is called when the overall system is running low on memory, and actively running processes should trim their memory usage.
From interface android.content.ComponentCallbacks2 abstract void onTrimMemory(int level) Called when the operating system has determined that it is a good time for a process to trim unneeded memory from its process.
From interface android.content.DialogInterface.OnCancelListener abstract void onCancel(DialogInterface dialog) This method will be invoked when the dialog is canceled.
From interface android.content.DialogInterface.OnDismissListener abstract void onDismiss(DialogInterface dialog) This method will be invoked when the dialog is dismissed.
From interface android.view.View.OnCreateContextMenuListener abstract void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) Called when the context menu for this view is being built.