SwitchBootstraps

public class SwitchBootstraps
extends Object

java.lang.Object
↳	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
`static CallSite`	`enumSwitch(MethodHandles.Lookup lookup, String invocationName, MethodType invocationType, Object... labels)` Bootstrap method for linking an `invokedynamic` call site that implements a `switch` on a target of an enum type.
`static CallSite`	`typeSwitch(MethodHandles.Lookup lookup, String invocationName, MethodType invocationType, Object... labels)` Bootstrap method for linking an `invokedynamic` call site that implements a `switch` on a target of a reference type.

Inherited methods

From class


        
          java.lang.Object

`Object`	`clone()` Creates and returns a copy of this object.
`boolean`	`equals(Object obj)` Indicates whether some other object is "equal to" this one.
`void`	`finalize()` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
`final Class<?>`	`getClass()` Returns the runtime class of this `Object`.
`int`	`hashCode()` Returns a hash code value for the object.
`final void`	`notify()` Wakes up a single thread that is waiting on this object's monitor.
`final void`	`notifyAll()` Wakes up all threads that are waiting on this object's monitor.
`String`	`toString()` Returns a string representation of the object.
`final void`	`wait(long timeoutMillis, int nanos)` Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait(long timeoutMillis)` Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait()` Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

Public methods

enumSwitch

Added in API level 36

public static CallSite enumSwitch (MethodHandles.Lookup lookup, 
                String invocationName, 
                MethodType invocationType, 
                Object... labels)

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().

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 is thrown.

Parameters
`lookup`	`MethodHandles.Lookup`: Represents a lookup context with the accessibility privileges of the caller. When used with `invokedynamic`, this is stacked automatically by the VM.
`invocationName`	`String`: unused
`invocationType`	`MethodType`: The invocation type of the `CallSite` with two parameters, an enum type, an `int`, and `int` as a return type.
`labels`	`Object`: case labels - `String` constants and `Class` instances, in any combination

Returns
`CallSite`	a `CallSite` returning the first matching element as described above

Throws
`NullPointerException`	if any argument is `null`
`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

public static CallSite typeSwitch (MethodHandles.Lookup lookup, 
                String invocationName, 
                MethodType invocationType, 
                Object... labels)

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.

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 is thrown.

Parameters
`lookup`	`MethodHandles.Lookup`: Represents a lookup context with the accessibility privileges of the caller. When used with `invokedynamic`, this is stacked automatically by the VM.
`invocationName`	`String`: unused
`invocationType`	`MethodType`: The invocation type of the `CallSite` with two parameters, a reference type, an `int`, and `int` as a return type.
`labels`	`Object`: case labels - `String` and `Integer` constants and `Class` and `EnumDesc` instances, in any combination

Returns
`CallSite`	a `CallSite` returning the first matching element as described above

Throws
`NullPointerException`	if any argument is `null`
`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`.