java.lang.Object | ||
↳ | android.app.Fragment | |
↳ | android.app.DialogFragment |
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:
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.
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.
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.
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();
Constants | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
int | STYLE_NORMAL | Style for setStyle(int, int) : a basic,
normal dialog. |
|||||||||
int | STYLE_NO_FRAME | Style for setStyle(int, int) : don't draw
any frame at all; the view hierarchy returned by onCreateView(LayoutInflater, ViewGroup, Bundle)
is entirely responsible for drawing the dialog. |
|||||||||
int | STYLE_NO_INPUT | Style for setStyle(int, int) : like
STYLE_NO_FRAME , but also disables all input to the dialog. |
|||||||||
int | STYLE_NO_TITLE | Style for setStyle(int, int) : don't include
a title area. |
[Expand]
Inherited Constants | |||||||||||
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From interface
android.content.ComponentCallbacks2
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Public Constructors | |||||||||||
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Public Methods | |||||||||||
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Dismiss the fragment and its dialog.
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Version of
dismiss() that uses
FragmentTransaction.commitAllowingStateLoss() . | |||||||||||
Print the Fragments's state into the given stream.
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Return the current value of
setShowsDialog(boolean) . | |||||||||||
Return the current value of
setCancelable(boolean) . | |||||||||||
Called when the fragment's activity has been created and this
fragment's view hierarchy instantiated.
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Called when a fragment is first attached to its activity.
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This method will be invoked when the dialog is canceled.
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Called to do initial creation of a fragment.
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Override to build your own custom Dialog container.
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Remove dialog.
| |||||||||||
Called when the fragment is no longer attached to its activity.
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This method will be invoked when the dialog is dismissed.
| |||||||||||
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.
| |||||||||||
Called when the Fragment is visible to the user.
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Called when the Fragment is no longer started.
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Control whether the shown Dialog is cancelable.
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Controls whether this fragment should be shown in a dialog.
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Call to customize the basic appearance and behavior of the
fragment's dialog.
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Display the dialog, adding the fragment using an existing transaction
and then committing the transaction.
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Display the dialog, adding the fragment to the given FragmentManager.
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[Expand]
Inherited Methods | |||||||||||
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From class
android.app.Fragment
| |||||||||||
From class
java.lang.Object
| |||||||||||
From interface
android.content.ComponentCallbacks
| |||||||||||
From interface
android.content.ComponentCallbacks2
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From interface
android.content.DialogInterface.OnCancelListener
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From interface
android.content.DialogInterface.OnDismissListener
| |||||||||||
From interface
android.view.View.OnCreateContextMenuListener
|
Style for setStyle(int, int)
: a basic,
normal dialog.
Style for setStyle(int, int)
: don't draw
any frame at all; the view hierarchy returned by onCreateView(LayoutInflater, ViewGroup, Bundle)
is entirely responsible for drawing the dialog.
Style for setStyle(int, int)
: like
STYLE_NO_FRAME
, but also disables all input to the dialog.
The user can not touch it, and its window will not receive input focus.
Style for setStyle(int, int)
: don't include
a title area.
Dismiss the fragment and its dialog. If the fragment was added to the back stack, all back stack state up to and including this entry will be popped. Otherwise, a new transaction will be committed to remove the fragment.
Version of dismiss()
that uses
FragmentTransaction.commitAllowingStateLoss()
. See linked
documentation for further details.
Print the Fragments's state into the given stream.
prefix | Text to print at the front of each line. |
---|---|
fd | The raw file descriptor that the dump is being sent to. |
writer | The PrintWriter to which you should dump your state. This will be closed for you after you return. |
args | additional arguments to the dump request. |
Return the current value of setShowsDialog(boolean)
.
Return the current value of setCancelable(boolean)
.
Called when the fragment's activity has been created and this
fragment's view hierarchy instantiated. It can be used to do final
initialization once these pieces are in place, such as retrieving
views or restoring state. It is also useful for fragments that use
setRetainInstance(boolean)
to retain their instance,
as this callback tells the fragment when it is fully associated with
the new activity instance. This is called after onCreateView(LayoutInflater, ViewGroup, Bundle)
and before onViewStateRestored(Bundle)
.
savedInstanceState | If the fragment is being re-created from a previous saved state, this is the state. |
---|
Called when a fragment is first attached to its activity.
onCreate(Bundle)
will be called after this.
This method will be invoked when the dialog is canceled.
dialog | The dialog that was canceled will be passed into the method. |
---|
Called to do initial creation of a fragment. This is called after
onAttach(Activity)
and before
onCreateView(LayoutInflater, ViewGroup, Bundle)
.
Note that this can be called while the fragment's activity is
still in the process of being created. As such, you can not rely
on things like the activity's content view hierarchy being initialized
at this point. If you want to do work once the activity itself is
created, see onActivityCreated(Bundle)
.
savedInstanceState | If the fragment is being re-created from a previous saved state, this is the state. |
---|
Override to build your own custom Dialog container. This is typically
used to show an AlertDialog instead of a generic Dialog; when doing so,
onCreateView(LayoutInflater, ViewGroup, Bundle)
does not need
to be implemented since the AlertDialog takes care of its own content.
This method will be called after onCreate(Bundle)
and
before onCreateView(LayoutInflater, ViewGroup, Bundle)
. The
default implementation simply instantiates and returns a Dialog
class.
Note: DialogFragment own the Dialog.setOnCancelListener
and Dialog.setOnDismissListener
callbacks. You must not set them yourself.
To find out about these events, override onCancel(DialogInterface)
and onDismiss(DialogInterface)
.
savedInstanceState | The last saved instance state of the Fragment, or null if this is a freshly created Fragment. |
---|
Called when the fragment is no longer attached to its activity. This
is called after onDestroy()
.
This method will be invoked when the dialog is dismissed.
dialog | The dialog that was dismissed will be passed into the method. |
---|
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. If a new instance of the fragment later needs to be
created, the data you place in the Bundle here will be available
in the Bundle given to onCreate(Bundle)
,
onCreateView(LayoutInflater, ViewGroup, Bundle)
, and
onActivityCreated(Bundle)
.
This corresponds to Activity.onSaveInstanceState(Bundle)
and most of the discussion there
applies here as well. Note however: this method may be called
at any time before onDestroy()
. There are many situations
where a fragment may be mostly torn down (such as when placed on the
back stack with no UI showing), but its state will not be saved until
its owning activity actually needs to save its state.
outState | Bundle in which to place your saved state. |
---|
Called when the Fragment is visible to the user. This is generally
tied to Activity.onStart
of the containing
Activity's lifecycle.
Called when the Fragment is no longer started. This is generally
tied to Activity.onStop
of the containing
Activity's lifecycle.
Control whether the shown Dialog is cancelable. Use this instead of
directly calling Dialog.setCancelable(boolean)
, because DialogFragment needs to change
its behavior based on this.
cancelable | If true, the dialog is cancelable. The default is true. |
---|
Controls whether this fragment should be shown in a dialog. If not
set, no Dialog will be created in onActivityCreated(Bundle)
,
and the fragment's view hierarchy will thus not be added to it. This
allows you to instead use it as a normal fragment (embedded inside of
its activity).
This is normally set for you based on whether the fragment is
associated with a container view ID passed to
FragmentTransaction.add(int, Fragment)
.
If the fragment was added with a container, setShowsDialog will be
initialized to false; otherwise, it will be true.
showsDialog | If true, the fragment will be displayed in a Dialog. If false, no Dialog will be created and the fragment's view hierarchly left undisturbed. |
---|
Call to customize the basic appearance and behavior of the fragment's dialog. This can be used for some common dialog behaviors, taking care of selecting flags, theme, and other options for you. The same effect can be achieve by manually setting Dialog and Window attributes yourself. Calling this after the fragment's Dialog is created will have no effect.
style | Selects a standard style: may be STYLE_NORMAL ,
STYLE_NO_TITLE , STYLE_NO_FRAME , or
STYLE_NO_INPUT . |
---|---|
theme | Optional custom theme. If 0, an appropriate theme (based on the style) will be selected for you. |
Display the dialog, adding the fragment using an existing transaction and then committing the transaction.
transaction | An existing transaction in which to add the fragment. |
---|---|
tag | The tag for this fragment, as per
FragmentTransaction.add . |
FragmentTransaction.commit()
.
Display the dialog, adding the fragment to the given FragmentManager. This is a convenience for explicitly creating a transaction, adding the fragment to it with the given tag, and committing it. This does not add the transaction to the back stack. When the fragment is dismissed, a new transaction will be executed to remove it from the activity.
manager | The FragmentManager this fragment will be added to. |
---|---|
tag | The tag for this fragment, as per
FragmentTransaction.add .
|