Added in API level 34

ObjectMethods

public class ObjectMethods
extends Object

java.lang.Object
   ↳ java.lang.runtime.ObjectMethods


Bootstrap methods for state-driven implementations of core methods, including Object.equals(Object), Object.hashCode(), and Object.toString(). These methods may be used, for example, by Java compiler implementations to implement the bodies of Object methods for record classes.

Summary

Public methods

static Object bootstrap(MethodHandles.Lookup lookup, String methodName, TypeDescriptor type, Class<?> recordClass, String names, MethodHandle... getters)

Bootstrap method to generate the Object.equals(Object), Object.hashCode(), and Object.toString() methods, based on a description of the component names and accessor methods, for either invokedynamic call sites or dynamic constant pool entries.

Inherited methods

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

bootstrap

Added in API level 34
public static Object bootstrap (MethodHandles.Lookup lookup, 
                String methodName, 
                TypeDescriptor type, 
                Class<?> recordClass, 
                String names, 
                MethodHandle... getters)

Bootstrap method to generate the Object.equals(Object), Object.hashCode(), and Object.toString() methods, based on a description of the component names and accessor methods, for either invokedynamic call sites or dynamic constant pool entries. For more detail on the semantics of the generated methods see the specification of Record.equals(Object), Record.hashCode() and Record.toString().

Parameters
lookup MethodHandles.Lookup: Every bootstrap method is expected to have a lookup which usually represents a lookup context with the accessibility privileges of the caller. This is because invokedynamic call sites always provide a lookup to the corresponding bootstrap method, but this method just ignores the lookup parameter

methodName String: the name of the method to generate, which must be one of "equals", "hashCode", or "toString"

type TypeDescriptor: a MethodType corresponding the descriptor type for the method, which must correspond to the descriptor for the corresponding Object method, if linking an invokedynamic call site, or the constant MethodHandle.class, if linking a dynamic constant

recordClass Class: the record class hosting the record components

names String: the list of component names, joined into a string separated by ";", or the empty string if there are no components. Maybe be null, if the methodName is "equals" or "hashCode".

getters MethodHandle: method handles for the accessor methods for the components

Returns
Object a call site if invoked by indy, or a method handle if invoked by a condy

Throws
IllegalArgumentException if the bootstrap arguments are invalid or inconsistent
Throwable if any exception is thrown during call site construction