# Interface ProviderFactory

@NonExtensible @ServiceScope(org.gradle.internal.service.scopes.Scope.Build.class) public interface ProviderFactory
A factory for creating instances of `Provider`.

An instance of the factory can be injected into a task, plugin or other object by annotating a public constructor or property getter method with `javax.inject.Inject`. It is also available via `Project.getProviders()` and `Settings.getProviders()`.

Since:
  4.0

- ## Method Summary

  Modifier and Type
  Method
  Description
  `<T extends Credentials>
  Provider<T>`
  `credentials(Class<T> credentialsType, String identity)`
  Creates a `Provider` for the given `Credentials` type.
  `<T extends Credentials>
  Provider<T>`
  `credentials(Class<T> credentialsType, Provider<String> identity)`
  Creates a `Provider` for the given `Credentials` type.
  `Provider<String>`
  `environmentVariable(String variableName)`
  Creates a `Provider` whose value is fetched from the environment variable with the given name.
  `Provider<String>`
  `environmentVariable(Provider<String> variableName)`
  Creates a `Provider` whose value is fetched from the environment variable with the given name.
  `Provider<Map<String,String>>`
  `environmentVariablesPrefixedBy(String variableNamePrefix)`
  Creates a `Provider` whose value is a name-to-value map of the environment variables with the names starting with the given prefix.
  `Provider<Map<String,String>>`
  `environmentVariablesPrefixedBy(Provider<String> variableNamePrefix)`
  Creates a `Provider` whose value is a name-to-value map of the environment variables with the names starting with the given prefix.
  `ExecOutput`
  `exec(Action<? super ExecSpec> action)`
  Allows lazy access to the output of the external process.
  `FileContents`
  `fileContents(RegularFile file)`
  Allows lazy access to the contents of the given file.
  `FileContents`
  `fileContents(Provider<RegularFile> file)`
  Allows lazy access to the contents of the given file.
  `Provider<Map<String,String>>`
  `gradlePropertiesPrefixedBy(String propertyNamePrefix)`
  Creates a `Provider` whose value is a name-to-value map of the Gradle properties with the names starting with the given prefix.
  `Provider<Map<String,String>>`
  `gradlePropertiesPrefixedBy(Provider<String> propertyNamePrefix)`
  Creates a `Provider` whose value is a name-to-value map of the Gradle properties with the names starting with the given prefix.
  `Provider<String>`
  `gradleProperty(String propertyName)`
  Creates a `Provider` whose value is fetched from the Gradle property of the given name.
  `Provider<String>`
  `gradleProperty(Provider<String> propertyName)`
  Creates a `Provider` whose value is fetched from the Gradle property of the given name.
  `ExecOutput`
  `javaexec(Action<? super JavaExecSpec> action)`
  Allows lazy access to the output of the external java process.
  `<T, P extends ValueSourceParameters>
  Provider<T>`
  `of(Class<? extends ValueSource<T,P>> valueSourceType, Action<? super ValueSourceSpec<P>> configuration)`
  Creates a `Provider` whose value is obtained from the given `ValueSource`.
  `<T> Provider<T>`
  `provider(Callable<? extends @Nullable T> value)`
  Creates a `Provider` whose value is calculated using the given `Callable`.
  `Provider<Map<String,String>>`
  `systemPropertiesPrefixedBy(String variableNamePrefix)`
  Creates a `Provider` whose value is a name-to-value map of the system properties with the names starting with the given prefix.
  `Provider<Map<String,String>>`
  `systemPropertiesPrefixedBy(Provider<String> variableNamePrefix)`
  Creates a `Provider` whose value is a name-to-value map of the system properties with the names starting with the given prefix.
  `Provider<String>`
  `systemProperty(String propertyName)`
  Creates a `Provider` whose value is fetched from system properties using the given property name.
  `Provider<String>`
  `systemProperty(Provider<String> propertyName)`
  Creates a `Provider` whose value is fetched from system properties using the given property name.
  `<A,B,R> Provider<R>`
  `zip(Provider<A> first, Provider<B> second, BiFunction<? super A, ? super B, ? extends R> combiner)`
  Returns a provider which value will be computed by combining a provider value with another provider value using the supplied combiner function.

- ## Method Details

  - ### provider

    <T> Provider<T> provider(Callable<? extends @Nullable T> value)
    Creates a `Provider` whose value is calculated using the given `Callable`.

    The provider is live and will call the `Callable` each time its value is queried. The `Callable` may return `null`, in which case the provider is considered to have no value.

    #### Configuration Cache

    This provider is always computed and its value is cached by the Configuration Cache. If this provider is created at configuration time, the `Callable` may call configuration-time only APIs and capture objects of arbitrary types.

    This can be useful when you need to lazily compute some value to use at execution time based on configuration-time only data. For example, you can compute an archive name based on the name and the version of the project:

          tasks.register("createArchive") {
              def archiveNameProvider = providers.provider { project.name + "-" + project.version + ".jar" }
              doLast {
                  def archiveName = new File(archiveNameProvider.get())
                  // ... create the archive and put in its contents.
              }
          }

    Parameters:
      `value` - The `java.util.concurrent.Callable` use to calculate the value.
    Returns:
      The provider. Never returns null.

  - ### environmentVariable

    Provider<String> environmentVariable(String variableName)
    Creates a `Provider` whose value is fetched from the environment variable with the given name.
    Parameters:
      `variableName` - The name of the environment variable.
    Returns:
      The provider. Never returns null.
    Since:
      6.1

  - ### environmentVariable

    Provider<String> environmentVariable(Provider<String> variableName)
    Creates a `Provider` whose value is fetched from the environment variable with the given name.
    Parameters:
      `variableName` - The provider for the name of the environment variable; when the given provider has no value, the returned provider has no value.
    Returns:
      The provider. Never returns null.
    Since:
      6.1

  - ### environmentVariablesPrefixedBy

    Provider<Map<String,String>> environmentVariablesPrefixedBy(String variableNamePrefix)
    Creates a `Provider` whose value is a name-to-value map of the environment variables with the names starting with the given prefix. The prefix comparison is case-sensitive. The returned map is immutable.
    Parameters:
      `variableNamePrefix` - The prefix of the environment variable names
    Returns:
      The provider. Never returns null.
    Since:
      7.5

  - ### environmentVariablesPrefixedBy

    Provider<Map<String,String>> environmentVariablesPrefixedBy(Provider<String> variableNamePrefix)
    Creates a `Provider` whose value is a name-to-value map of the environment variables with the names starting with the given prefix. The prefix comparison is case-sensitive. The returned map is immutable.
    Parameters:
      `variableNamePrefix` - The prefix of the environment variable names
    Returns:
      The provider. Never returns null.
    Since:
      7.5

  - ### systemProperty

    Provider<String> systemProperty(String propertyName)
    Creates a `Provider` whose value is fetched from system properties using the given property name.
    Parameters:
      `propertyName` - the name of the system property
    Returns:
      the provider for the system property, never returns null
    Since:
      6.1

  - ### systemProperty

    Provider<String> systemProperty(Provider<String> propertyName)
    Creates a `Provider` whose value is fetched from system properties using the given property name.
    Parameters:
      `propertyName` - the name of the system property
    Returns:
      the provider for the system property, never returns null
    Since:
      6.1

  - ### systemPropertiesPrefixedBy

    Provider<Map<String,String>> systemPropertiesPrefixedBy(String variableNamePrefix)
    Creates a `Provider` whose value is a name-to-value map of the system properties with the names starting with the given prefix. The prefix comparison is case-sensitive. The returned map is immutable.
    Parameters:
      `variableNamePrefix` - The prefix of the system property names
    Returns:
      The provider. Never returns null.
    Since:
      7.5

  - ### systemPropertiesPrefixedBy

    Provider<Map<String,String>> systemPropertiesPrefixedBy(Provider<String> variableNamePrefix)
    Creates a `Provider` whose value is a name-to-value map of the system properties with the names starting with the given prefix. The prefix comparison is case-sensitive. The returned map is immutable.
    Parameters:
      `variableNamePrefix` - The prefix of the system property names
    Returns:
      The provider. Never returns null.
    Since:
      7.5

  - ### gradleProperty

    Provider<String> gradleProperty(String propertyName)
    Creates a `Provider` whose value is fetched from the Gradle property of the given name.

    The property value is resolved from the following sources, in order of priority:

    1. Command-line project properties (`-P` arguments)
    2. System properties with the `org.gradle.project.` prefix
    3. Environment variables with the `ORG_GRADLE_PROJECT_` prefix
    4. `gradle.properties` in the Gradle User Home directory
    5. `gradle.properties` in the build root directory
    6. `gradle.properties` in the Gradle installation directory

    Note that this method resolves properties at the build level. It does not include properties from `gradle.properties` files in subproject directories, nor does it include extra properties or other properties set dynamically on individual `Project` instances.

    More information on project properties.

    Parameters:
      `propertyName` - the name of the Gradle property
    Returns:
      the provider for the Gradle property, never returns null
    Since:
      6.2

  - ### gradleProperty

    Provider<String> gradleProperty(Provider<String> propertyName)
    Creates a `Provider` whose value is fetched from the Gradle property of the given name.

    The property value is resolved from the following sources, in order of priority:

    1. Command-line project properties (`-P` arguments)
    2. System properties with the `org.gradle.project.` prefix
    3. Environment variables with the `ORG_GRADLE_PROJECT_` prefix
    4. `gradle.properties` in the Gradle User Home directory
    5. `gradle.properties` in the build root directory
    6. `gradle.properties` in the Gradle installation directory

    Note that this method resolves properties at the build level. It does not include properties from `gradle.properties` files in subproject directories, nor does it include extra properties or other properties set dynamically on individual `Project` instances.

    More information on project properties.

    Parameters:
      `propertyName` - the name of the Gradle property
    Returns:
      the provider for the Gradle property, never returns null
    Since:
      6.2

  - ### gradlePropertiesPrefixedBy

    Provider<Map<String,String>> gradlePropertiesPrefixedBy(String propertyNamePrefix)
    Creates a `Provider` whose value is a name-to-value map of the Gradle properties with the names starting with the given prefix. The prefix comparison is case-sensitive. The returned map is immutable.

    Properties are resolved at the build level from the same sources as `gradleProperty(String)`.

    More information on project properties.

    Parameters:
      `propertyNamePrefix` - The prefix of the Gradle property names
    Returns:
      The provider. Never returns null.
    Since:
      8.0

  - ### gradlePropertiesPrefixedBy

    Provider<Map<String,String>> gradlePropertiesPrefixedBy(Provider<String> propertyNamePrefix)
    Creates a `Provider` whose value is a name-to-value map of the Gradle properties with the names starting with the given prefix. The prefix comparison is case-sensitive. The returned map is immutable.

    Properties are resolved at the build level from the same sources as `gradleProperty(String)`.

    More information on project properties.

    Parameters:
      `propertyNamePrefix` - The prefix of the Gradle property names
    Returns:
      The provider. Never returns null.
    Since:
      8.0

  - ### fileContents

    FileContents fileContents(RegularFile file)
    Allows lazy access to the contents of the given file.

    When the file contents are read at configuration time the file is automatically considered as an input to the configuration model.

    Parameters:
      `file` - the file whose contents to read.
    Returns:
      an interface that allows lazy access to the contents of the given file.
    Since:
      6.1
    See Also:
      - `FileContents.getAsText()`
      - `FileContents.getAsBytes()`

  - ### fileContents

    FileContents fileContents(Provider<RegularFile> file)
    Allows lazy access to the contents of the given file.

    When the file contents are read at configuration time the file is automatically considered as an input to the configuration model.

    Parameters:
      `file` - provider of the file whose contents to read.
    Returns:
      an interface that allows lazy access to the contents of the given file.
    Since:
      6.1
    See Also:
      - `FileContents.getAsText()`
      - `FileContents.getAsBytes()`

  - ### exec

    ExecOutput exec(Action<? super ExecSpec> action)
    Allows lazy access to the output of the external process.

    When the process output is read at configuration time it is considered as an input to the configuration model. Consequent builds will re-execute the process to obtain the output and check if the cached model is still up-to-date.

    The process input and output streams cannot be configured.

    For more sophisticated use cases, like handling execution exceptions, supplying input streams or processing the output in a streaming way, use `ValueSource`.

    Parameters:
      `action` - the configuration of the external process with the output stream pre-configured.
    Returns:
      an interface that allows lazy access to the process' output.
    Since:
      7.5

  - ### javaexec

    ExecOutput javaexec(Action<? super JavaExecSpec> action)
    Allows lazy access to the output of the external java process.

    When the process output is read at configuration time it is considered as an input to the configuration model. Consequent builds will re-execute the process to obtain the output and check if the cached model is still up-to-date.

    The process input and output streams cannot be configured.

    For more sophisticated use cases, like handling execution exceptions, supplying input streams or processing the output in a streaming way, use `ValueSource`.

    Parameters:
      `action` - the configuration of the external process with the output stream pre-configured.
    Returns:
      an interface that allows lazy access to the process' output.
    Since:
      7.5

  - ### of

    <T, P extends ValueSourceParameters> Provider<T> of(Class<? extends ValueSource<T,P>> valueSourceType, Action<? super ValueSourceSpec<P>> configuration)
    Creates a `Provider` whose value is obtained from the given `ValueSource`.
    Parameters:
      `valueSourceType` - the type of the `ValueSource`
      `configuration` - action to configure the parameters to the given `ValueSource`
    Returns:
      the provider, never returns null
    Since:
      6.1

  - ### credentials

    <T extends Credentials> Provider<T> credentials(Class<T> credentialsType, String identity)
    Creates a `Provider` for the given `Credentials` type.

    The provider returned by this method should be attached to a task's input property. This way, the presence of credentials will be validated before any of the tasks are executed if and only if the task with credentials property is to be executed.

    Values for the requested Credentials type will be sourced from the project's properties using the pattern "identity" + credentials field. For example, `PasswordCredentials` provider with identity "myService" will look for properties named "myServiceUsername" and "myServicePassword".

    The following credential types are currently supported:

    - `PasswordCredentials`
    - `AwsCredentials`
    Parameters:
      `credentialsType` - type of credentials to be provided.
      `identity` - identity to be associated with the credentials.
    Returns:
      The provider. Never returns null.
    Since:
      6.6

  - ### credentials

    <T extends Credentials> Provider<T> credentials(Class<T> credentialsType, Provider<String> identity)
    Creates a `Provider` for the given `Credentials` type.

    The provider returned by this method should be attached to a task's input property. This way, the presence of credentials will be validated before any of the tasks are executed if and only if the task with credentials property is to be executed.

    Values for the requested Credentials type will be sourced from the project's properties using the pattern "identity" + credentials field. For example, `PasswordCredentials` provider with identity "myService" will look for properties named "myServiceUsername" and "myServicePassword".

    The following credential types are currently supported:

    - `PasswordCredentials`
    - `AwsCredentials`
    Parameters:
      `credentialsType` - type of credentials to be provided.
      `identity` - a provider returning the identity to be associated with the credentials.
    Returns:
      The provider. Never returns null.
    Since:
      6.6

  - ### zip

    <A,B,R> Provider<R> zip(Provider<A> first, Provider<B> second, BiFunction<? super A, ? super B, ? extends R> combiner)
    Returns a provider which value will be computed by combining a provider value with another provider value using the supplied combiner function.

    The resulting provider will be live, so that each time it is queried, it queries both supplied providers and applies the combiner to the results. Whenever any of the providers has no value, the new provider will also have no value and the combiner will not be called.

    If the supplied providers represents a task or the output of a task, the resulting provider will carry the dependency information.

    Type Parameters:
      `A` - the type of the first provider
      `B` - the type of the second provider
      `R` - the type of the result of the combiner
    Parameters:
      `first` - the first provider to combine with
      `second` - the second provider to combine with
      `combiner` - the combiner of values. May return `null`, in which case the provider will have no value.
    Returns:
      a combined provider
    Since:
      6.6