# SwitchBootstraps Added in[API level 36](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels) # SwitchBootstraps ``` open class SwitchBootstraps ``` |---|--------------------------------------------------------------------------------------------------------------------------| | [kotlin.Any](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-any/index.html) || | ↳ | [java.lang.runtime.SwitchBootstraps](https://developer.android.com/reference/kotlin/java/lang/runtime/SwitchBootstraps#) | Bootstrap methods for linking`invokedynamic`call sites that implement the selection functionality of the`switch`statement. The bootstraps take additional static arguments corresponding to the`case`labels of the`switch`, implicitly numbered sequentially from`[0..N)`. ## Summary | Public methods || |-------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | openstatic[CallSite](https://developer.android.com/reference/kotlin/java/lang/invoke/CallSite.html#)! | [enumSwitch](https://developer.android.com/reference/kotlin/java/lang/runtime/SwitchBootstraps#enumSwitch(java.lang.invoke.MethodHandles.Lookup,%20kotlin.String,%20java.lang.invoke.MethodType,%20kotlin.Any))`(`lookup:` `[MethodHandles.Lookup](https://developer.android.com/reference/kotlin/java/lang/invoke/MethodHandles.Lookup.html#)!`, `invocationName:` `[String](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-string/index.html)!`, `invocationType:` `[MethodType](https://developer.android.com/reference/kotlin/java/lang/invoke/MethodType.html#)!`, `vararg` `labels:` `[Any](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-any/index.html)!`)` Bootstrap method for linking an`invokedynamic`call site that implements a`switch`on a target of an enum type. | | openstatic[CallSite](https://developer.android.com/reference/kotlin/java/lang/invoke/CallSite.html#)! | [typeSwitch](https://developer.android.com/reference/kotlin/java/lang/runtime/SwitchBootstraps#typeSwitch(java.lang.invoke.MethodHandles.Lookup,%20kotlin.String,%20java.lang.invoke.MethodType,%20kotlin.Any))`(`lookup:` `[MethodHandles.Lookup](https://developer.android.com/reference/kotlin/java/lang/invoke/MethodHandles.Lookup.html#)!`, `invocationName:` `[String](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-string/index.html)!`, `invocationType:` `[MethodType](https://developer.android.com/reference/kotlin/java/lang/invoke/MethodType.html#)!`, `vararg` `labels:` `[Any](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-any/index.html)!`)` Bootstrap method for linking an`invokedynamic`call site that implements a`switch`on a target of a reference type. | ## Public methods ### enumSwitch Added in[API level 36](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels) ``` open static fun enumSwitch(     lookup: MethodHandles.Lookup!,     invocationName: String!,     invocationType: MethodType!,     vararg labels: Any! ): CallSite! ``` Bootstrap method for linking an`invokedynamic`call site that implements a`switch`on a target of an enum type. The static arguments are used to encode the case labels associated to the switch construct, where each label can be encoded in two ways: - as a`String`value, which represents the name of the enum constant associated with the label - as a`Class`value, which represents the enum type associated with a type test pattern
The returned`CallSite`'s method handle will have a return type of`int`and accepts two parameters: the first argument will be an`Enum`instance (`target`) and the second will be`int`(`restart`). If the`target`is`null`, then the method of the call site returns -1. If the`target`is not`null`, then the method of the call site returns the index of the first element in the`labels`array starting from the`restart`index matching one of the following conditions: - the element is of type`Class`that is assignable from the target's class; or - the element is of type`String`and equals to the target enum constant's[Enum.name()](https://developer.android.com/reference/kotlin/java/lang/Enum.html#name()). If no element in the`labels`array matches the target, then the method of the call site return the length of the`labels`array. The value of the`restart`index must be between`0`(inclusive) and the length of the`labels`array (inclusive), both or an[IndexOutOfBoundsException](https://developer.android.com/reference/kotlin/java/lang/IndexOutOfBoundsException.html#)is thrown. | Parameters || |------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | `lookup` | [MethodHandles.Lookup](https://developer.android.com/reference/kotlin/java/lang/invoke/MethodHandles.Lookup.html#)!:Represents a lookup context with the accessibility privileges of the caller. When used with`invokedynamic`, this is stacked automatically by the VM. | | `invocationName` | [String](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-string/index.html)!:unused | | `invocationType` | [MethodType](https://developer.android.com/reference/kotlin/java/lang/invoke/MethodType.html#)!:The invocation type of the`CallSite`with two parameters, an enum type, an`int`, and`int`as a return type. | | `labels` | [Any](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-any/index.html)!:case labels -`String`constants and`Class`instances, in any combination | | Return || |---------------------------------------------------------------------------------------------|--------------------------------------------------------------------| | [CallSite](https://developer.android.com/reference/kotlin/java/lang/invoke/CallSite.html#)! | a`CallSite`returning the first matching element as described above | | Exceptions || |--------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | `java.lang.NullPointerException` | if any argument is`null` | | `java.lang.IllegalArgumentException` | if any element in the labels array is null, if the invocation type is not a method type whose first parameter type is an enum type, second parameter of type`int`and whose return type is`int`, or if`labels`contains an element that is not of type`String`or`Class`of the target enum type. | ### typeSwitch Added in[API level 36](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels) ``` open static fun typeSwitch(     lookup: MethodHandles.Lookup!,     invocationName: String!,     invocationType: MethodType!,     vararg labels: Any! ): CallSite! ``` Bootstrap method for linking an`invokedynamic`call site that implements a`switch`on a target of a reference type. The static arguments are an array of case labels which must be non-null and of type`String`or`Integer`or`Class`or`EnumDesc`. The type of the returned`CallSite`'s method handle will have a return type of`int`. It has two parameters: the first argument will be an`Object`instance (`target`) and the second will be`int`(`restart`). If the`target`is`null`, then the method of the call site returns -1. If the`target`is not`null`, then the method of the call site returns the index of the first element in the`labels`array starting from the`restart`index matching one of the following conditions: - the element is of type`Class`that is assignable from the target's class; or - the element is of type`String`or`Integer`and equals to the target. - the element is of type`EnumDesc`, that describes a constant that is equals to the target. If no element in the`labels`array matches the target, then the method of the call site return the length of the`labels`array. The value of the`restart`index must be between`0`(inclusive) and the length of the`labels`array (inclusive), both or an[IndexOutOfBoundsException](https://developer.android.com/reference/kotlin/java/lang/IndexOutOfBoundsException.html#)is thrown. | Parameters || |------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | `lookup` | [MethodHandles.Lookup](https://developer.android.com/reference/kotlin/java/lang/invoke/MethodHandles.Lookup.html#)!:Represents a lookup context with the accessibility privileges of the caller. When used with`invokedynamic`, this is stacked automatically by the VM. | | `invocationName` | [String](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-string/index.html)!:unused | | `invocationType` | [MethodType](https://developer.android.com/reference/kotlin/java/lang/invoke/MethodType.html#)!:The invocation type of the`CallSite`with two parameters, a reference type, an`int`, and`int`as a return type. | | `labels` | [Any](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-any/index.html)!:case labels -`String`and`Integer`constants and`Class`and`EnumDesc`instances, in any combination | | Return || |---------------------------------------------------------------------------------------------|--------------------------------------------------------------------| | [CallSite](https://developer.android.com/reference/kotlin/java/lang/invoke/CallSite.html#)! | a`CallSite`returning the first matching element as described above | | Exceptions || |--------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | `java.lang.NullPointerException` | if any argument is`null` | | `java.lang.IllegalArgumentException` | if any element in the labels array is null, if the invocation type is not not a method type of first parameter of a reference type, second parameter of type`int`and with`int`as its return type, or if`labels`contains an element that is not of type`String`,`Integer`,`Class`or`EnumDesc`. |