org.gradle.api
[Java] Interface Task

org.gradle.api.plugins.ExtensionAware
  org.gradle.api.Task

All Superinterfaces:

ExtensionAware

public interface Task
extends Comparable, ExtensionAware

A Task represents a single atomic piece of work for a build, such as compiling classes or generating javadoc.

Each task belongs to a Project. You can use the various methods on TaskContainer to create and lookup task instances. For example, TaskContainer.add creates an empty task with the given name. You can also use the task keyword in your build file:

 task myTask
 task myTask { configure closure }
 task myType << { task action }
 task myTask(type: SomeType)
 task myTask(type: SomeType) { configure closure }
 

Each task has a name, which can be used to refer to the task within its owning project, and a fully qualified path, which is unique across all tasks in all projects. The path is the concatenation of the owning project's path and the task's name. Path elements are separated using the {

value:

org.gradle.api.Project#PATH_SEPARATOR} character.

Task Actions

A Task is made up of a sequence of Action objects. When the task is executed, each of the actions is executed in turn, by calling Action#execute#execute. You can add actions to a task by calling doFirst(Action) or doLast(Action).

Groovy closures can also be used to provide a task action. When the action is executed, the closure is called with the task as parameter. You can add action closures to a task by calling doFirst(groovy.lang.Closure) or doLast(groovy.lang.Closure) or using the left-shift << operator.

There are 2 special exceptions which a task action can throw to abort execution and continue without failing the build. A task action can abort execution of the action and continue to the next action of the task by throwing a StopActionException. A task action can abort execution of the task and continue to the next task by throwing a StopExecutionException. Using these exceptions allows you to have precondition actions which skip execution of the task, or part of the task, if not true.

Task Dependencies and Task Ordering

A task may have dependencies on other tasks or might be scheduled to always run after another task. Gradle ensures that all task dependencies and ordering rules are honored when executing tasks, so that the task is executed after all of it's dependencies and any "must run after" tasks have been executed.

Dependencies to a task are controlled using dependsOn(Object...) or setDependsOn(Iterable), and mustRunAfter(Object...) or setMustRunAfter(Iterable) are used to specify ordering between tasks. You can use objects of any of the following types to specify dependencies and ordering:

• A String, CharSequence or groovy.lang.GString task path or name. A relative path is interpreted relative to the task's Project. This allows you to refer to tasks in other projects.
• A Task.
• A closure. The closure may take a Task as parameter. It may return any of the types listed here. Its return value is recursively converted to tasks. A null return value is treated as an empty collection.
• A TaskDependency object.
• A Buildable object.
• A Iterable, Collection, Map or array. May contain any of the types listed here. The elements of the iterable/collection/map/array are recursively converted to tasks.
• A Callable. The call() method may return any of the types listed here. Its return value is recursively converted to tasks. A null return value is treated as an empty collection.
• An Object. The object's toString() method is interpreted as a task path or name. The support for custom Objects has been deprecated and will be removed in the next version of Gradle.

Using a Task in a Build File

Dynamic Properties

A Task has 3 'scopes' for properties. You can access these properties by name from the build file or by calling the property(String) method.

• The Task object itself. This includes any property getters and setters declared by the Task implementation class. The properties of this scope are readable or writable based on the presence of the corresponding getter and setter methods.
• The additional properties of the task. Each task object maintains a map of additional properties. These are arbitrary name -> value pairs which you can use to dynamically add properties to a task object. The properties of this scope are readable and writable.
• The convention properties added to the task by each Plugin applied to the project. A Plugin can add properties and methods to a task through the task's Convention object. The properties of this scope may be readable or writable, depending on the convention objects.

Dynamic Methods

A Plugin may add methods to a Task using its Convention object.

Authors:

Hans Dockter

TASK_ACTION

public static final String TASK_ACTION

TASK_DEPENDS_ON

public static final String TASK_DEPENDS_ON

TASK_DESCRIPTION

public static final String TASK_DESCRIPTION

TASK_GROUP

public static final String TASK_GROUP

TASK_NAME

public static final String TASK_NAME

TASK_OVERWRITE

public static final String TASK_OVERWRITE

TASK_TYPE

public static final String TASK_TYPE

configure

public Task configure(Closure configureClosure)

Applies the statements of the closure against this task object. The delegate object for the closure is set to this task.

Parameters:

configureClosure - The closure to be applied (can be null).

Returns:

This task

deleteAllActions

public Task deleteAllActions()

Removes all the actions of this task.

Returns:

the task object this method is applied to

dependsOn

public Task dependsOn(Object... paths)

Adds the given dependencies to this task. See here for a description of the types of objects which can be used as task dependencies.

Parameters:

paths - The dependencies to add to this task. The path can be defined by:

A String, CharSequence or groovy.lang.GString task path or name. A relative path is interpreted relative to the task's Project. This allows you to refer to tasks in other projects.

A Task.

A closure. The closure may take a Task as parameter. It may return any of the types listed here. Its return value is recursively converted to tasks. A null return value is treated as an empty collection.

A TaskDependency object.

A Buildable object.

A Iterable, Collection, Map or array. May contain any of the types listed here. The elements of the iterable/collection/map/array are recursively converted to tasks.

A Callable. The call() method may return any of the types listed here. Its return value is recursively converted to tasks. A null return value is treated as an empty collection.

An Object. The object's toString() method is interpreted as a task path or name. The support for custom Objects has been deprecated and will be removed in the next version of Gradle.

Returns:

the task object this method is applied to

dependsOnTaskDidWork

public boolean dependsOnTaskDidWork()

Checks if any of the tasks that this task depends on Task#getDidWork()#getDidWork().

Returns:

true if any task this task depends on did work.

doFirst

public Task doFirst(Action action)

Adds the given Action to the beginning of this task's action list.

Parameters:

action - The action to add

Returns:

the task object this method is applied to

doFirst

public Task doFirst(Closure action)

Adds the given closure to the beginning of this task's action list. The closure is passed this task as a parameter when executed.

Parameters:

action - The action closure to execute.

Returns:

This task.

doLast

public Task doLast(Action action)

Adds the given Action to the end of this task's action list.

Parameters:

action - The action to add.

Returns:

the task object this method is applied to

doLast

public Task doLast(Closure action)

Adds the given closure to the end of this task's action list. The closure is passed this task as a parameter when executed.

Parameters:

action - The action closure to execute.

Returns:

This task.

finalizedBy

@Incubating
public Task finalizedBy(Object... paths)

Adds the given finalizer tasks for this task.

 task taskY {
     finalizedBy "taskX"
 }
 

See here for a description of the types of objects which can be used to specify a finalizer task.

Parameters:

paths - The tasks that finalize this task.

Returns:

the task object this method is applied to

getActions

public List getActions()

Returns the sequence of Action objects which will be executed by this task, in the order of execution.

Returns:

The task actions in the order they are executed. Returns an empty list if this task has no actions.

getAnt

public AntBuilder getAnt()

Returns the AntBuilder for this task. You can use this in your build file to execute ant tasks.

Returns:

The AntBuilder

getConvention

public Convention getConvention()

Returns the Convention object for this task. A Plugin can use the convention object to contribute properties and methods to this task.

Returns:

The convention object. Never returns null.

getDependsOn

public Set getDependsOn()

Returns the dependencies of this task.

Returns:

The dependencies of this task. Returns an empty set if this task has no dependencies.

getDescription

public String getDescription()

Returns the description of this task.

Returns:

the description. May return null.

getDidWork

public boolean getDidWork()

Checks if the task actually did any work. Even if a Task executes, it may determine that it has nothing to do. For example, the Compile task may determine that source files have not changed since the last time a the task was run.

Returns:

true if this task did any work

getEnabled

public boolean getEnabled()

Returns if this task is enabled or not.

See Also:

setEnabled(boolean)

getFinalizedBy

@Incubating
public TaskDependency getFinalizedBy()

Returns tasks that finalize this task.

Returns:

The tasks that finalize this task. Returns an empty set if there are no finalising tasks for this task.

getGroup

public String getGroup()

Returns the task group which this task belongs to. The task group is used in reports and user interfaces to group related tasks together when presenting a list of tasks to the user.

Returns:

The task group for this task. Might be null.

getInputs

public TaskInputs getInputs()

Returns the inputs of this task.

Returns:

The inputs. Never returns null.

getLogger

public Logger getLogger()

Returns the logger for this task. You can use this in your build file to write log messages.

Returns:

The logger. Never returns null.

getLogging

public LoggingManager getLogging()

Returns the LoggingManager which can be used to control the logging level and standard output/error capture for this task. By default, System.out is redirected to the Gradle logging system at the QUIET log level, and System.err is redirected at the ERROR log level.

Returns:

the LoggingManager. Never returns null.

getMustRunAfter

@Incubating
public TaskDependency getMustRunAfter()

Returns tasks that this task must run after.

Returns:

The tasks that this task must run after. Returns an empty set if this task has no tasks it must run after.

getName

public String getName()

Returns the name of this task. The name uniquely identifies the task within its Project.

Returns:

The name of the task. Never returns null.

getOutputs

public TaskOutputs getOutputs()

Returns the outputs of this task.

Returns:

The outputs. Never returns null.

getPath

public String getPath()

Returns the path of the task, which is a fully qualified name for the task. The path of a task is the path of its Project plus the name of the task, separated by :.

Returns:

the path of the task, which is equal to the path of the project plus the name of the task.

getProject

public Project getProject()

Returns the Project which this task belongs to.

Returns:

The project this task belongs to. Never returns null.

getState

public TaskState getState()

Returns the execution state of this task. This provides information about the execution of this task, such as whether it has executed, been skipped, has failed, etc.

Returns:

The execution state of this task. Never returns null.

getTaskDependencies

public TaskDependency getTaskDependencies()

Returns a TaskDependency which contains all the tasks that this task depends on.

Returns:

The dependencies of this task. Never returns null.

getTemporaryDir

public File getTemporaryDir()

Returns a directory which this task can use to write temporary files to. Each task instance is provided with a separate temporary directory. There are no guarantees that the contents of this directory will be kept beyond the execution of the task.

Returns:

The directory. Never returns null. The directory will already exist.

hasProperty

public boolean hasProperty(String propertyName)

Determines if this task has the given property. See here for details of the properties which are available for a task.

Parameters:

propertyName - The name of the property to locate.

Returns:

True if this project has the given property, false otherwise.

leftShift

public Task leftShift(Closure action)

Adds the given closure to the end of this task's action list. The closure is passed this task as a parameter when executed. You can call this method from your build script using the << left shift operator.

Parameters:

action - The action closure to execute.

Returns:

This task.

mustRunAfter

@Incubating
public Task mustRunAfter(Object... paths)

Specifies that this task must run after all of the supplied tasks.

 task taskY {
     mustRunAfter "taskX"
 }
 

For each supplied task, this action adds a task 'ordering', and does not specify a 'dependency' between the tasks. As such, it is still possible to execute 'taskY' without first executing the 'taskX' in the example.

See here for a description of the types of objects which can be used to specify an ordering relationship.

Parameters:

paths - The tasks this task must run after.

Returns:

the task object this method is applied to

onlyIf

public void onlyIf(Closure onlyIfClosure)

Execute the task only if the given closure returns true. The closure will be evaluated at task execution time, not during configuration. The closure will be passed a single parameter, this task. If the closure returns false, the task will be skipped.

You may add multiple such predicates. The task is skipped if any of the predicates return false.

Typical usage:myTask.onlyIf{ dependsOnTaskDidWork() }

Parameters:

onlyIfClosure - code to execute to determine if task should be run

onlyIf

public void onlyIf(Spec onlyIfSpec)

Execute the task only if the given spec is satisfied. The spec will be evaluated at task execution time, not during configuration. If the Spec is not satisfied, the task will be skipped.

You may add multiple such predicates. The task is skipped if any of the predicates return false.

Typical usage (from Java):

myTask.onlyIf(new Spec<Task>() {
    boolean isSatisfiedBy(Task task) {
       return task.dependsOnTaskDidWork();
    }
 });
 

Parameters:

onlyIfSpec - specifies if a task should be run

property

public Object property(String propertyName)

Returns the value of the given property of this task. This method locates a property as follows:

1. If this task object has a property with the given name, return the value of the property.
2. If this task has an additional property with the given name, return the value of the property.
3. If this task's convention object has a property with the given name, return the value of the property.
4. If not found, throw MissingPropertyException

throws:

MissingPropertyException When the given property is unknown.

Parameters:

propertyName - The name of the property.

Returns:

The value of the property, possibly null.

setActions

public void setActions(List actions)

Sets the sequence of Action objects which will be executed by this task.

Parameters:

actions - The actions.

setDependsOn

public void setDependsOn(Iterable dependsOnTasks)

Sets the dependencies of this task. See here for a description of the types of objects which can be used as task dependencies.

Parameters:

dependsOnTasks - The set of task paths.

setDescription

public void setDescription(String description)

Sets a description for this task. This should describe what the task does to the user of the build. The description will be displayed when gradle tasks is called.

Parameters:

description - The description of the task. Might be null.

setDidWork

public void setDidWork(boolean didWork)

Sets whether the task actually did any work. Most built-in tasks will set this automatically, but it may be useful to manually indicate this for custom user tasks.

This is useful when combined with onlyIf { dependsOnTaskDidWork() }.

Parameters:

didWork - indicates if the task did any work

setEnabled

public void setEnabled(boolean enabled)

Set the enabled state of a task. If a task is disabled none of the its actions are executed. Note that disabling a task does not prevent the execution of the tasks which this task depends on.

Parameters:

enabled - The enabled state of this task (true or false)

setFinalizedBy

@Incubating
public void setFinalizedBy(Iterable finalizedBy)

Specifies the set of finalizer tasks for this task.

 task taskY {
     finalizedBy = ["taskX1", "taskX2"]
 }
 

See here for a description of the types of objects which can be used to specify a finalizer task.

Parameters:

finalizedBy - The tasks that finalize this task.

Returns:

the task object this method is applied to

setGroup

public void setGroup(String group)

Sets the task group which this task belongs to. The task group is used in reports and user interfaces to group related tasks together when presenting a list of tasks to the user.

Parameters:

group - The task group for this task. Can be null.

setMustRunAfter

@Incubating
public void setMustRunAfter(Iterable mustRunAfter)

Specifies the set of tasks that this task must run after.

 task taskY {
     mustRunAfter = ["taskX1", "taskX2"]
 }
 

For each supplied task, this action adds a task 'ordering', and does not specify a 'dependency' between the tasks. As such, it is still possible to execute 'taskY' without first executing the 'taskX' in the example.

See here for a description of the types of objects which can be used to specify an ordering relationship.

Parameters:

mustRunAfter - The set of task paths this task must run after.

setOnlyIf

public void setOnlyIf(Closure onlyIfClosure)

Execute the task only if the given closure returns true. The closure will be evaluated at task execution time, not during configuration. The closure will be passed a single parameter, this task. If the closure returns false, the task will be skipped.

The given predicate replaces all such predicates for this task.

Parameters:

onlyIfClosure - code to execute to determine if task should be run

setOnlyIf

public void setOnlyIf(Spec onlyIfSpec)

Execute the task only if the given spec is satisfied. The spec will be evaluated at task execution time, not during configuration. If the Spec is not satisfied, the task will be skipped.

The given predicate replaces all such predicates for this task.

Parameters:

onlyIfSpec - specifies if a task should be run

setProperty

public void setProperty(String name, Object value)

Sets a property of this task. This method searches for a property with the given name in the following locations, and sets the property on the first location where it finds the property.

1. The task object itself. For example, the enabled project property.
2. The task's convention object.
3. The task's additional properties.

If the property is not found in any of these locations, it is added to the project's additional properties.

Parameters:

name - The name of the property

value - The value of the property

Gradle API 1.7