```
@Target({TYPE,FIELD,METHOD,CONSTRUCTOR})
@Retention(CLASS)
public @interface UsedByReflection
```
Annotation to mark a class, field or method as being accessed reflectively.
Note: Before using this annotation, consider if instead you can annotate the code that is doing reflection with UsesReflection. Annotating the reflecting code is generally more clear and maintainable, and it also naturally gives rise to edges that describe just the reflected aspects of the program. The UsedByReflection annotation is suitable for cases where the reflecting code is not under user control, or in migrating away from rules.
When a class is annotated, member patterns can be used to define which members are to be kept. When no member patterns are specified the default pattern is to match just the class.
When a member is annotated, the member patterns cannot be used as the annotated member itself fully defines the item to be kept (i.e., itself).

Optional Element Summary

Optional Elements
Modifier and Type	Optional Element	Description
`KeepTarget[]`	`additionalTargets`	Additional targets to be kept in addition to the annotated class/members.
`AnnotationPattern[]`	`constrainAnnotations`	Patterns for annotations that must remain on the item.
`KeepConstraint[]`	`constraintAdditions`	Add additional usage constraints of the target.
`KeepConstraint[]`	`constraints`	Define the usage constraints of the target.
`java.lang.String`	`description`	Optional description to document the reason for this annotation.
`FieldAccessFlags[]`	`fieldAccess`	Define the field-access pattern by matching on access flags.
`java.lang.Class<?>`	`fieldAnnotatedByClassConstant`	Define the field-annotated-by pattern by reference to a Class constant.
`java.lang.String`	`fieldAnnotatedByClassName`	Define the field-annotated-by pattern by fully qualified class name.
`ClassNamePattern`	`fieldAnnotatedByClassNamePattern`	Define the field-annotated-by pattern by reference to a class-name pattern.
`java.lang.String`	`fieldName`	Define the field-name pattern by an exact field name.
`StringPattern`	`fieldNamePattern`	Define the field-name pattern by a string pattern.
`java.lang.String`	`fieldType`	Define the field-type pattern by a fully qualified type.
`java.lang.Class<?>`	`fieldTypeConstant`	Define the field-type pattern by a class constant.
`TypePattern`	`fieldTypePattern`	Define the field-type pattern by a pattern on types.
`KeepItemKind`	`kind`	Specify the kind of this item pattern.
`MemberAccessFlags[]`	`memberAccess`	Define the member-access pattern by matching on access flags.
`java.lang.Class<?>`	`memberAnnotatedByClassConstant`	Define the member-annotated-by pattern by reference to a Class constant.
`java.lang.String`	`memberAnnotatedByClassName`	Define the member-annotated-by pattern by fully qualified class name.
`ClassNamePattern`	`memberAnnotatedByClassNamePattern`	Define the member-annotated-by pattern by reference to a class-name pattern.
`MethodAccessFlags[]`	`methodAccess`	Define the method-access pattern by matching on access flags.
`java.lang.Class<?>`	`methodAnnotatedByClassConstant`	Define the method-annotated-by pattern by reference to a Class constant.
`java.lang.String`	`methodAnnotatedByClassName`	Define the method-annotated-by pattern by fully qualified class name.
`ClassNamePattern`	`methodAnnotatedByClassNamePattern`	Define the method-annotated-by pattern by reference to a class-name pattern.
`java.lang.String`	`methodName`	Define the method-name pattern by an exact method name.
`StringPattern`	`methodNamePattern`	Define the method-name pattern by a string pattern.
`java.lang.String[]`	`methodParameters`	Define the method parameters pattern by a list of fully qualified types.
`TypePattern[]`	`methodParameterTypePatterns`	Define the method parameters pattern by a list of patterns on types.
`java.lang.String`	`methodReturnType`	Define the method return-type pattern by a fully qualified type or 'void'.
`java.lang.Class<?>`	`methodReturnTypeConstant`	Define the method return-type pattern by a class constant.
`TypePattern`	`methodReturnTypePattern`	Define the method return-type pattern by a type pattern.
`KeepCondition[]`	`preconditions`	Conditions that should be satisfied for the annotation to be in effect.

- Element Detail
  - description
```
java.lang.String description
```
    Optional description to document the reason for this annotation.
    
    Returns:
    
    The descriptive message. Defaults to no description.
    
    Default:
    
    ""
- - preconditions
```
KeepCondition[] preconditions
```
    Conditions that should be satisfied for the annotation to be in effect.
    
    Returns:
    
    The list of preconditions. Defaults to no conditions, thus trivially/unconditionally satisfied.
    
    Default:
    
    {}
- - additionalTargets
```
KeepTarget[] additionalTargets
```
    Additional targets to be kept in addition to the annotated class/members.
    
    Returns:
    
    List of additional target consequences. Defaults to no additional target consequences.
    
    Default:
    
    {}
- - kind
```
KeepItemKind kind
```
    Specify the kind of this item pattern.
    If unspecified the default kind depends on the annotated item.
    When annotating a class the default kind is:
    
    KeepItemKind.ONLY_CLASS if no member patterns are defined;
    KeepItemKind.CLASS_AND_METHODS if method patterns are defined;
    KeepItemKind.CLASS_AND_FIELDS if field patterns are defined;
    KeepItemKind.CLASS_AND_MEMBERS otherwise.
    
    When annotating a method the default kind is: KeepItemKind.ONLY_METHODS
    When annotating a field the default kind is: KeepItemKind.ONLY_FIELDS
    It is not possible to use KeepItemKind.ONLY_CLASS if annotating a member.
    Returns:
    
    The kind for this pattern.
    
    Default:
    
    com.android.tools.r8.keepanno.annotations.KeepItemKind.DEFAULT
- - constraints
```
KeepConstraint[] constraints
```
    Define the usage constraints of the target.
    The specified constraints must remain valid for the target.
    The default constraints depend on the kind of the target. For all targets the default constraints include:
    
    KeepConstraint.LOOKUP
    KeepConstraint.NAME
    KeepConstraint.VISIBILITY_RELAX
    
    For classes the default constraints also include:
    
    KeepConstraint.CLASS_INSTANTIATE
    
    For methods the default constraints also include:
    
    KeepConstraint.METHOD_INVOKE
    
    For fields the default constraints also include:
    
    KeepConstraint.FIELD_GET
    KeepConstraint.FIELD_SET
    
    Mutually exclusive with the property `constraintAdditions` also defining constraints.
    Returns:
    
    Usage constraints for the target.
    
    Default:
    
    {}
- - constraintAdditions
```
KeepConstraint[] constraintAdditions
```
    Add additional usage constraints of the target.
    The specified constraints must remain valid for the target in addition to the default constraints.
    The default constraints are documented in constraints()
    Mutually exclusive with the property `constraints` also defining constraints.
    
    Returns:
    
    Additional usage constraints for the target.
    
    Default:
    
    {}
- - constrainAnnotations
```
AnnotationPattern[] constrainAnnotations
```
    Patterns for annotations that must remain on the item.
    The annotations matching any of the patterns must remain on the item if the annotation types remain in the program.
    Note that if the annotation types themselves are unused/removed, then their references on the item will be removed too. If the annotation types themselves are used reflectively then they too need a keep annotation or rule to ensure they remain in the program.
    By default no annotation patterns are defined and no annotations are required to remain.
    
    Returns:
    
    Annotation patterns
    
    Default:
    
    {}
- - memberAnnotatedByClassName
```
java.lang.String memberAnnotatedByClassName
```
    Define the member-annotated-by pattern by fully qualified class name.
    Mutually exclusive with the following other properties defining member-annotated-by:
    
    memberAnnotatedByClassConstant
    memberAnnotatedByClassNamePattern
    
    Mutually exclusive with all field and method properties as use restricts the match to both types of members.
    If none are specified the default is to match any member regardless of what the member is annotated by.
    Returns:
    
    The qualified class name that defines the annotation.
    
    Default:
    
    ""
- - memberAnnotatedByClassConstant
```
java.lang.Class<?> memberAnnotatedByClassConstant
```
    Define the member-annotated-by pattern by reference to a Class constant.
    Mutually exclusive with the following other properties defining member-annotated-by:
    
    memberAnnotatedByClassName
    memberAnnotatedByClassNamePattern
    
    Mutually exclusive with all field and method properties as use restricts the match to both types of members.
    If none are specified the default is to match any member regardless of what the member is annotated by.
    Returns:
    
    The class-constant that defines the annotation.
    
    Default:
    
    java.lang.Object.class
- - memberAnnotatedByClassNamePattern
```
ClassNamePattern memberAnnotatedByClassNamePattern
```
    Define the member-annotated-by pattern by reference to a class-name pattern.
    Mutually exclusive with the following other properties defining member-annotated-by:
    
    memberAnnotatedByClassName
    memberAnnotatedByClassConstant
    
    Mutually exclusive with all field and method properties as use restricts the match to both types of members.
    If none are specified the default is to match any member regardless of what the member is annotated by.
    Returns:
    
    The class-name pattern that defines the annotation.
    
    Default:
    
    @com.android.tools.r8.keepanno.annotations.ClassNamePattern(unqualifiedName="")
- - memberAccess
```
MemberAccessFlags[] memberAccess
```
    Define the member-access pattern by matching on access flags.
    Mutually exclusive with all field and method properties as use restricts the match to both types of members.
    
    Returns:
    
    The member access-flag constraints that must be met.
    
    Default:
    
    {}
- - methodAnnotatedByClassName
```
java.lang.String methodAnnotatedByClassName
```
    Define the method-annotated-by pattern by fully qualified class name.
    Mutually exclusive with the following other properties defining method-annotated-by:
    
    methodAnnotatedByClassConstant
    methodAnnotatedByClassNamePattern
    
    Mutually exclusive with all field properties.
    If none are specified the default is to match any method regardless of what the method is annotated by.
    Returns:
    
    The qualified class name that defines the annotation.
    
    Default:
    
    ""
- - methodAnnotatedByClassConstant
```
java.lang.Class<?> methodAnnotatedByClassConstant
```
    Define the method-annotated-by pattern by reference to a Class constant.
    Mutually exclusive with the following other properties defining method-annotated-by:
    
    methodAnnotatedByClassName
    methodAnnotatedByClassNamePattern
    
    Mutually exclusive with all field properties.
    If none are specified the default is to match any method regardless of what the method is annotated by.
    Returns:
    
    The class-constant that defines the annotation.
    
    Default:
    
    java.lang.Object.class
- - methodAnnotatedByClassNamePattern
```
ClassNamePattern methodAnnotatedByClassNamePattern
```
    Define the method-annotated-by pattern by reference to a class-name pattern.
    Mutually exclusive with the following other properties defining method-annotated-by:
    
    methodAnnotatedByClassName
    methodAnnotatedByClassConstant
    
    Mutually exclusive with all field properties.
    If none are specified the default is to match any method regardless of what the method is annotated by.
    Returns:
    
    The class-name pattern that defines the annotation.
    
    Default:
    
    @com.android.tools.r8.keepanno.annotations.ClassNamePattern(unqualifiedName="")
- - methodAccess
```
MethodAccessFlags[] methodAccess
```
    Define the method-access pattern by matching on access flags.
    Mutually exclusive with all field properties.
    If none, and other properties define this item as a method, the default matches any method-access flags.
    
    Returns:
    
    The method access-flag constraints that must be met.
    
    Default:
    
    {}
- - methodName
```
java.lang.String methodName
```
    Define the method-name pattern by an exact method name.
    Mutually exclusive with all field properties.
    If none, and other properties define this item as a method, the default matches any method name.
    Mutually exclusive with the property `methodNamePattern` also defining method-name.
    
    Returns:
    
    The exact method name of the method.
    
    Default:
    
    ""
- - methodNamePattern
```
StringPattern methodNamePattern
```
    Define the method-name pattern by a string pattern.
    Mutually exclusive with all field properties.
    If none, and other properties define this item as a method, the default matches any method name.
    Mutually exclusive with the property `methodName` also defining method-name.
    
    Returns:
    
    The string pattern of the method name.
    
    Default:
    
    @com.android.tools.r8.keepanno.annotations.StringPattern(exact="")
- - methodReturnType
```
java.lang.String methodReturnType
```
    Define the method return-type pattern by a fully qualified type or 'void'.
    Mutually exclusive with all field properties.
    If none, and other properties define this item as a method, the default matches any return type.
    Mutually exclusive with the following other properties defining return-type:
    
    methodReturnTypeConstant
    methodReturnTypePattern
    Returns:
    
    The qualified type name of the method return type.
    
    Default:
    
    ""
- - methodReturnTypeConstant
```
java.lang.Class<?> methodReturnTypeConstant
```
    Define the method return-type pattern by a class constant.
    Mutually exclusive with all field properties.
    If none, and other properties define this item as a method, the default matches any return type.
    Mutually exclusive with the following other properties defining return-type:
    
    methodReturnType
    methodReturnTypePattern
    Returns:
    
    A class constant denoting the type of the method return type.
    
    Default:
    
    java.lang.Object.class
- - methodReturnTypePattern
```
TypePattern methodReturnTypePattern
```
    Define the method return-type pattern by a type pattern.
    Mutually exclusive with all field properties.
    If none, and other properties define this item as a method, the default matches any return type.
    Mutually exclusive with the following other properties defining return-type:
    
    methodReturnType
    methodReturnTypeConstant
    Returns:
    
    The pattern of the method return type.
    
    Default:
    
    @com.android.tools.r8.keepanno.annotations.TypePattern(name="")
- - methodParameters
```
java.lang.String[] methodParameters
```
    Define the method parameters pattern by a list of fully qualified types.
    Mutually exclusive with all field properties.
    If none, and other properties define this item as a method, the default matches any parameters.
    Mutually exclusive with the property `methodParameterTypePatterns` also defining parameters.
    
    Returns:
    
    The list of qualified type names of the method parameters.
    
    Default:
    
    {""}
- - methodParameterTypePatterns
```
TypePattern[] methodParameterTypePatterns
```
    Define the method parameters pattern by a list of patterns on types.
    Mutually exclusive with all field properties.
    If none, and other properties define this item as a method, the default matches any parameters.
    Mutually exclusive with the property `methodParameters` also defining parameters.
    
    Returns:
    
    The list of type patterns for the method parameters.
    
    Default:
    
    {@com.android.tools.r8.keepanno.annotations.TypePattern(name="")}
- - fieldAnnotatedByClassName
```
java.lang.String fieldAnnotatedByClassName
```
    Define the field-annotated-by pattern by fully qualified class name.
    Mutually exclusive with the following other properties defining field-annotated-by:
    
    fieldAnnotatedByClassConstant
    fieldAnnotatedByClassNamePattern
    
    Mutually exclusive with all method properties.
    If none are specified the default is to match any field regardless of what the field is annotated by.
    Returns:
    
    The qualified class name that defines the annotation.
    
    Default:
    
    ""
- - fieldAnnotatedByClassConstant
```
java.lang.Class<?> fieldAnnotatedByClassConstant
```
    Define the field-annotated-by pattern by reference to a Class constant.
    Mutually exclusive with the following other properties defining field-annotated-by:
    
    fieldAnnotatedByClassName
    fieldAnnotatedByClassNamePattern
    
    Mutually exclusive with all method properties.
    If none are specified the default is to match any field regardless of what the field is annotated by.
    Returns:
    
    The class-constant that defines the annotation.
    
    Default:
    
    java.lang.Object.class
- - fieldAnnotatedByClassNamePattern
```
ClassNamePattern fieldAnnotatedByClassNamePattern
```
    Define the field-annotated-by pattern by reference to a class-name pattern.
    Mutually exclusive with the following other properties defining field-annotated-by:
    
    fieldAnnotatedByClassName
    fieldAnnotatedByClassConstant
    
    Mutually exclusive with all method properties.
    If none are specified the default is to match any field regardless of what the field is annotated by.
    Returns:
    
    The class-name pattern that defines the annotation.
    
    Default:
    
    @com.android.tools.r8.keepanno.annotations.ClassNamePattern(unqualifiedName="")
- - fieldAccess
```
FieldAccessFlags[] fieldAccess
```
    Define the field-access pattern by matching on access flags.
    Mutually exclusive with all method properties.
    If none, and other properties define this item as a field, the default matches any field-access flags.
    
    Returns:
    
    The field access-flag constraints that must be met.
    
    Default:
    
    {}
- - fieldName
```
java.lang.String fieldName
```
    Define the field-name pattern by an exact field name.
    Mutually exclusive with all method properties.
    If none, and other properties define this item as a field, the default matches any field name.
    Mutually exclusive with the property `fieldNamePattern` also defining field-name.
    
    Returns:
    
    The exact field name of the field.
    
    Default:
    
    ""
- - fieldNamePattern
```
StringPattern fieldNamePattern
```
    Define the field-name pattern by a string pattern.
    Mutually exclusive with all method properties.
    If none, and other properties define this item as a field, the default matches any field name.
    Mutually exclusive with the property `fieldName` also defining field-name.
    
    Returns:
    
    The string pattern of the field name.
    
    Default:
    
    @com.android.tools.r8.keepanno.annotations.StringPattern(exact="")
- - fieldType
```
java.lang.String fieldType
```
    Define the field-type pattern by a fully qualified type.
    Mutually exclusive with all method properties.
    If none, and other properties define this item as a field, the default matches any type.
    Mutually exclusive with the following other properties defining field-type:
    
    fieldTypeConstant
    fieldTypePattern
    Returns:
    
    The qualified type name for the field type.
    
    Default:
    
    ""
- - fieldTypeConstant
```
java.lang.Class<?> fieldTypeConstant
```
    Define the field-type pattern by a class constant.
    Mutually exclusive with all method properties.
    If none, and other properties define this item as a field, the default matches any type.
    Mutually exclusive with the following other properties defining field-type:
    
    fieldType
    fieldTypePattern
    Returns:
    
    The class constant for the field type.
    
    Default:
    
    java.lang.Object.class
- - fieldTypePattern
```
TypePattern fieldTypePattern
```
    Define the field-type pattern by a pattern on types.
    Mutually exclusive with all method properties.
    If none, and other properties define this item as a field, the default matches any type.
    Mutually exclusive with the following other properties defining field-type:
    
    fieldType
    fieldTypeConstant
    Returns:
    
    The type pattern for the field type.
    
    Default:
    
    @com.android.tools.r8.keepanno.annotations.TypePattern(name="")

Annotation Type UsedByReflection

Optional Element Summary

Element Detail

description

preconditions

additionalTargets

kind

constraints

constraintAdditions

constrainAnnotations

memberAnnotatedByClassName

memberAnnotatedByClassConstant

memberAnnotatedByClassNamePattern

memberAccess

methodAnnotatedByClassName

methodAnnotatedByClassConstant

methodAnnotatedByClassNamePattern

methodAccess

methodName

methodNamePattern

methodReturnType

methodReturnTypeConstant

methodReturnTypePattern

methodParameters

methodParameterTypePatterns

fieldAnnotatedByClassName

fieldAnnotatedByClassConstant

fieldAnnotatedByClassNamePattern

fieldAccess

fieldName

fieldNamePattern

fieldType

fieldTypeConstant

fieldTypePattern