TaskStackBuilder

Added in 1.1.0

public final class TaskStackBuilder implements Iterable

Utility class for constructing synthetic back stacks for cross-task navigation on Android 3.0 and newer.

In API level 11 (Android 3.0/Honeycomb) the recommended conventions for app navigation using the back key changed. The back key's behavior is local to the current task and does not capture navigation across different tasks. Navigating across tasks and easily reaching the previous task is accomplished through the "recents" UI, accessible through the software-provided Recents key on the navigation or system bar. On devices with the older hardware button configuration the recents UI can be accessed with a long press on the Home key.

When crossing from one task stack to another post-Android 3.0, the application should synthesize a back stack/history for the new task so that the user may navigate out of the new task and back to the Launcher by repeated presses of the back key. Back key presses should not navigate across task stacks.

TaskStackBuilder provides a backward-compatible way to obey the correct conventions around cross-task navigation on the device's version of the platform. On devices running Android 3.0 or newer, calls to the startActivities method or sending the PendingIntent generated by getPendingIntent will construct the synthetic back stack as prescribed. On devices running older versions of the platform, these same calls will invoke the topmost activity in the supplied stack, ignoring the rest of the synthetic stack and allowing the back key to navigate back to the previous task.

### About Navigation For more detailed information about tasks, the back stack, and navigation design guidelines, please read from the developer guide and from the design guide.

Summary

Nested types

Public methods
@NonNull TaskStackBuilder

Add a new Intent to the task stack.
@NonNull TaskStackBuilder

Add a new Intent with the resolved chain of parents for the target activity to the task stack.
@NonNull TaskStackBuilder
addParentStack(@NonNull Activity sourceActivity)

Add the activity parent chain as specified by manifest elements to the task stack builder.
@NonNull TaskStackBuilder
addParentStack(@NonNull Class<Object> sourceActivityClass)

Add the activity parent chain as specified by manifest elements to the task stack builder.
@NonNull TaskStackBuilder
addParentStack(@NonNull ComponentName sourceActivityName)

Add the activity parent chain as specified by manifest elements to the task stack builder.
static @NonNull TaskStackBuilder

Return a new TaskStackBuilder for launching a fresh task stack consisting of a series of activities.
@Nullable Intent
editIntentAt(int index)

Return the intent at the specified index for modification.
static TaskStackBuilder
from(Context context)

This method is deprecated.

use create instead
Intent
getIntent(int index)

This method is deprecated.

Renamed to editIntentAt to better reflect intended usage
int
@NonNull Intent[]

Return an array containing the intents added to this builder.
@Nullable PendingIntent
getPendingIntent(int requestCode, int flags)

Obtain a PendingIntent for launching the task constructed by this builder so far.
@Nullable PendingIntent
getPendingIntent(int requestCode, int flags, boolean isMutable)

Obtains a PendingIntent with mandatory mutability flag set on supported platform versions.
@Nullable PendingIntent
getPendingIntent(int requestCode, int flags, @Nullable Bundle options)

Obtain a PendingIntent for launching the task constructed by this builder so far.
@Nullable PendingIntent
getPendingIntent(
    int requestCode,
    int flags,
    @Nullable Bundle options,
    boolean isMutable
)

Obtains a PendingIntent with mandatory mutability flag set on supported platform versions.
@NonNull Iterator<Intent>

This method is deprecated.

Use editIntentAt instead
void

Start the task stack constructed by this builder.
void

Start the task stack constructed by this builder.

Inherited methods
From java.lang.Iterable
void
forEach(Consumer<T> action)
Spliterator<T>

Public methods

addNextIntent

Added in 1.1.0
public @NonNull TaskStackBuilder addNextIntent(@NonNull Intent nextIntent)

Add a new Intent to the task stack. The most recently added Intent will invoke the Activity at the top of the final task stack.

Parameters
@NonNull Intent nextIntent

Intent for the next Activity in the synthesized task stack
Returns
@NonNull TaskStackBuilder

This TaskStackBuilder for method chaining

addNextIntentWithParentStack

Added in 1.1.0
public @NonNull TaskStackBuilder addNextIntentWithParentStack(@NonNull Intent nextIntent)

Add a new Intent with the resolved chain of parents for the target activity to the task stack.

This is equivalent to calling addParentStack with the resolved ComponentName of nextIntent (if it can be resolved), followed by addNextIntent with nextIntent.

Parameters
@NonNull Intent nextIntent

Intent for the topmost Activity in the synthesized task stack. Its chain of parents as specified in the manifest will be added.
Returns
@NonNull TaskStackBuilder

This TaskStackBuilder for method chaining.

addParentStack

Added in 1.1.0
public @NonNull TaskStackBuilder addParentStack(@NonNull Activity sourceActivity)

Add the activity parent chain as specified by manifest elements to the task stack builder.

Parameters
@NonNull Activity sourceActivity

All parents of this activity will be added
Returns
@NonNull TaskStackBuilder

This TaskStackBuilder for method chaining

addParentStack

Added in 1.1.0
public @NonNull TaskStackBuilder addParentStack(@NonNull Class<Object> sourceActivityClass)

Add the activity parent chain as specified by manifest elements to the task stack builder.

Parameters
@NonNull Class<Object> sourceActivityClass

All parents of this activity will be added
Returns
@NonNull TaskStackBuilder

This TaskStackBuilder for method chaining

addParentStack

Added in 1.1.0
public @NonNull TaskStackBuilder addParentStack(@NonNull ComponentName sourceActivityName)

Add the activity parent chain as specified by manifest elements to the task stack builder.

Parameters
@NonNull ComponentName sourceActivityName

Must specify an Activity component. All parents of this activity will be added
Returns
@NonNull TaskStackBuilder

This TaskStackBuilder for method chaining

create

Added in 1.1.0
public static @NonNull TaskStackBuilder create(@NonNull Context context)

Return a new TaskStackBuilder for launching a fresh task stack consisting of a series of activities.

Parameters
@NonNull Context context

The context that will launch the new task stack or generate a PendingIntent
Returns
@NonNull TaskStackBuilder

A new TaskStackBuilder

editIntentAt

Added in 1.1.0
public @Nullable Intent editIntentAt(int index)

Return the intent at the specified index for modification. Useful if you need to modify the flags or extras of an intent that was previously added, for example with addParentStack.

Parameters
int index

Index from 0-getIntentCount()
Returns
@Nullable Intent

the intent at position index

from

Added in 1.1.0
Deprecated in 1.1.0
public static TaskStackBuilder from(Context context)

Return a new TaskStackBuilder for launching a fresh task stack consisting of a series of activities.

Parameters
Context context

The context that will launch the new task stack or generate a PendingIntent
Returns
TaskStackBuilder

A new TaskStackBuilder

getIntent

Added in 1.1.0
Deprecated in 1.1.0
public Intent getIntent(int index)

Get the intent at the specified index. Useful if you need to modify the flags or extras of an intent that was previously added, for example with addParentStack.

Parameters
int index

Index from 0-getIntentCount()
Returns
Intent

the intent at position index

getIntentCount

Added in 1.1.0
public int getIntentCount()
Returns
int

the number of intents added so far.

getIntents

Added in 1.1.0
public @NonNull Intent[] getIntents()

Return an array containing the intents added to this builder. The intent at the root of the task stack will appear as the first item in the array and the intent at the top of the stack will appear as the last item.

Returns
@NonNull Intent[]

An array containing the intents added to this builder.

getPendingIntent

Added in 1.1.0
public @Nullable PendingIntent getPendingIntent(int requestCode, int flags)

Obtain a PendingIntent for launching the task constructed by this builder so far.

Parameters
int requestCode

Private request code for the sender
int flags

May be FLAG_ONE_SHOT, FLAG_NO_CREATE, FLAG_CANCEL_CURRENT, FLAG_UPDATE_CURRENT, or any of the flags supported by fillIn to control which unspecified parts of the intent that can be supplied when the actual send happens.
Returns
@Nullable PendingIntent

The obtained PendingIntent. May return null only if FLAG_NO_CREATE has been supplied.

getPendingIntent

public @Nullable PendingIntent getPendingIntent(int requestCode, int flags, boolean isMutable)

Obtains a PendingIntent with mandatory mutability flag set on supported platform versions. The caller provides the flag as combination of all the other values except mutability flag. This method combines mutability flag when necessary. See getPendingIntent.

getPendingIntent

Added in 1.1.0
public @Nullable PendingIntent getPendingIntent(int requestCode, int flags, @Nullable Bundle options)

Obtain a PendingIntent for launching the task constructed by this builder so far.

Parameters
int requestCode

Private request code for the sender
int flags

May be FLAG_ONE_SHOT, FLAG_NO_CREATE, FLAG_CANCEL_CURRENT, FLAG_UPDATE_CURRENT, or any of the flags supported by fillIn to control which unspecified parts of the intent that can be supplied when the actual send happens.
@Nullable Bundle options

Additional options for how the Activity should be started. See startActivity
Returns
@Nullable PendingIntent

The obtained PendingIntent. May return null only if FLAG_NO_CREATE has been supplied.

getPendingIntent

public @Nullable PendingIntent getPendingIntent(
    int requestCode,
    int flags,
    @Nullable Bundle options,
    boolean isMutable
)

Obtains a PendingIntent with mandatory mutability flag set on supported platform versions. The caller provides the flag as combination of all the other values except mutability flag. This method combines mutability flag when necessary. See getPendingIntent.

iterator

Added in 1.1.0
Deprecated in 1.1.0
public @NonNull Iterator<Intent> iterator()

startActivities

Added in 1.1.0
public void startActivities()

Start the task stack constructed by this builder. The Context used to obtain this builder must be an Activity.

On devices that do not support API level 11 or higher the topmost activity will be started as a new task. On devices that do support API level 11 or higher the new task stack will be created in its entirety.

startActivities

Added in 1.1.0
public void startActivities(@Nullable Bundle options)

Start the task stack constructed by this builder. The Context used to obtain this builder must be an Activity.

On devices that do not support API level 11 or higher the topmost activity will be started as a new task. On devices that do support API level 11 or higher the new task stack will be created in its entirety.

Parameters
@Nullable Bundle options

Additional options for how the Activity should be started. See startActivity