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package java.lang;


This is the common base class of all Java language record classes.

More information about records, including descriptions of the
implicitly declared methods synthesized by the compiler, can be
found in section 8.10 of
The Java Language Specification.

A record class is a shallowly immutable, transparent carrier for
a fixed set of values, called the record components.  The Java
language provides concise syntax for declaring record classes, whereby the
record components are declared in the record header.  The list of record
components declared in the record header form the record descriptor.

A record class has the following mandated members: a canonical
constructor, which must provide at least as much access as the record
class and whose descriptor is the same as the record descriptor;
a private final field corresponding to each component, whose name and
type are the same as that of the component; a public accessor method
corresponding to each component, whose name and return type are the same as
that of the component.  If not explicitly declared in the body of the record,
implicit implementations for these members are provided.

The implicit declaration of the canonical constructor has the same accessibility as the record class and initializes the component fields from the corresponding constructor arguments. The implicit declaration of the accessor methods returns the value of the corresponding component field. The implicit declaration of the Object.equals(Object), Object.hashCode(), and Object.toString() methods are derived from all of the component fields. 
The primary reasons to provide an explicit declaration for the
canonical constructor or accessor methods are to validate constructor
arguments, perform defensive copies on mutable components, or normalize groups
of components (such as reducing a rational number to lowest terms.)

For all record classes, the following invariant must hold: if a record R's components are c1, c2, ... cn, then if a record instance is copied as follows: 
    R copy = new R(r.c1(), r.c2(), ..., r.cn());

 then it must be the case that r.equals(copy). 
API Note: A record class that implements Serializable is said to be a serializable record. Serializable records are serialized and
deserialized differently than ordinary serializable objects. During
deserialization the record's canonical constructor is invoked to construct
the record object. Certain serialization-related methods, such as readObject
and writeObject, are ignored for serializable records. More information about
serializable records can be found in the

Java Object Serialization Specification, Section 1.13,
"Serialization of Records".
API Note: A record class structure can be obtained at runtime via reflection. See Class.isRecord() and Class.getRecordComponents() for more details.
@jls8.10 Record Types
Since:16
/**
 * This is the common base class of all Java language record classes.
 *
 * <p>More information about records, including descriptions of the
 * implicitly declared methods synthesized by the compiler, can be
 * found in section 8.10 of
 * <cite>The Java Language Specification</cite>.
 *
 * <p>A <em>record class</em> is a shallowly immutable, transparent carrier for
 * a fixed set of values, called the <em>record components</em>.  The Java
 * language provides concise syntax for declaring record classes, whereby the
 * record components are declared in the record header.  The list of record
 * components declared in the record header form the <em>record descriptor</em>.
 *
 * <p>A record class has the following mandated members: a <em>canonical
 * constructor</em>, which must provide at least as much access as the record
 * class and whose descriptor is the same as the record descriptor;
 * a private final field corresponding to each component, whose name and
 * type are the same as that of the component; a public accessor method
 * corresponding to each component, whose name and return type are the same as
 * that of the component.  If not explicitly declared in the body of the record,
 * implicit implementations for these members are provided.
 *
 * <p>The implicit declaration of the canonical constructor has the same accessibility
 * as the record class and initializes the component fields from the corresponding
 * constructor arguments.  The implicit declaration of the accessor methods returns
 * the value of the corresponding component field.  The implicit declaration of the
 * {@link Object#equals(Object)}, {@link Object#hashCode()}, and {@link Object#toString()}
 * methods are derived from all of the component fields.
 *
 * <p>The primary reasons to provide an explicit declaration for the
 * canonical constructor or accessor methods are to validate constructor
 * arguments, perform defensive copies on mutable components, or normalize groups
 * of components (such as reducing a rational number to lowest terms.)
 *
 * <p>For all record classes, the following invariant must hold: if a record R's
 * components are {@code c1, c2, ... cn}, then if a record instance is copied
 * as follows:
 * <pre>
 *     R copy = new R(r.c1(), r.c2(), ..., r.cn());
 * </pre>
 * then it must be the case that {@code r.equals(copy)}.
 *
 * @apiNote
 * A record class that {@code implements} {@link java.io.Serializable} is said
 * to be a <i>serializable record</i>. Serializable records are serialized and
 * deserialized differently than ordinary serializable objects. During
 * deserialization the record's canonical constructor is invoked to construct
 * the record object. Certain serialization-related methods, such as readObject
 * and writeObject, are ignored for serializable records. More information about
 * serializable records can be found in the
 * <a href="{@docRoot}/../specs/serialization/serial-arch.html#serialization-of-records">
 * <cite>Java Object Serialization Specification,</cite> Section 1.13,
 * "Serialization of Records"</a>.
 *
 * @apiNote
 * A record class structure can be obtained at runtime via reflection.
 * See {@link Class#isRecord()} and {@link Class#getRecordComponents()} for more details.
 *
 * @jls 8.10 Record Types
 * @since 16
 */
public abstract class Record {
    
Constructor for record classes to call.

/**
     * Constructor for record classes to call.
     */
    protected Record() {}

    
Indicates whether some other object is "equal to" this one. In addition to the general contract of Object.equals, record classes must further obey the invariant that when a record instance is "copied" by passing the result of the record component accessor methods to the canonical constructor, as follows: 
    R copy = new R(r.c1(), r.c2(), ..., r.cn());

 then it must be the case that r.equals(copy). 
Params:
  • obj –   the reference object with which to compare.
See Also:
Implementation Requirements: The implicitly provided implementation returns true if and only if the argument is an instance of the same record class as this record, and each component of this record is equal to the corresponding component of the argument; otherwise, 
false is returned. Equality of a component c is determined as follows: 
    

  •  If the component is of a reference type, the component is considered equal if and only if 
Objects.equals(this.c, r.c would return true. 
  •  If the component is of a primitive type, using the corresponding primitive wrapper class PW (the corresponding wrapper class for int is 
java.lang.Integer, and so on), the component is considered equal if and only if 
PW.compare(this.c, r.c) would return 0. 

Apart from the semantics described above, the precise algorithm
used in the implicitly provided implementation is unspecified
and is subject to change. The implementation may or may not use
calls to the particular methods listed, and may or may not
perform comparisons in the order of component declaration.
Returns: true if this record is equal to the argument; false otherwise.
/**
     * Indicates whether some other object is "equal to" this one.  In addition
     * to the general contract of {@link Object#equals(Object) Object.equals},
     * record classes must further obey the invariant that when
     * a record instance is "copied" by passing the result of the record component
     * accessor methods to the canonical constructor, as follows:
     * <pre>
     *     R copy = new R(r.c1(), r.c2(), ..., r.cn());
     * </pre>
     * then it must be the case that {@code r.equals(copy)}.
     *
     * @implSpec
     * The implicitly provided implementation returns {@code true} if
     * and only if the argument is an instance of the same record class
     * as this record, and each component of this record is equal to
     * the corresponding component of the argument; otherwise, {@code
     * false} is returned. Equality of a component {@code c} is
     * determined as follows:
     * <ul>
     *
     * <li> If the component is of a reference type, the component is
     * considered equal if and only if {@link
     * java.util.Objects#equals(Object,Object)
     * Objects.equals(this.c, r.c} would return {@code true}.
     *
     * <li> If the component is of a primitive type, using the
     * corresponding primitive wrapper class {@code PW} (the
     * corresponding wrapper class for {@code int} is {@code
     * java.lang.Integer}, and so on), the component is considered
     * equal if and only if {@code
     * PW.compare(this.c, r.c)} would return {@code 0}.
     *
     * </ul>
     *
     * Apart from the semantics described above, the precise algorithm
     * used in the implicitly provided implementation is unspecified
     * and is subject to change. The implementation may or may not use
     * calls to the particular methods listed, and may or may not
     * perform comparisons in the order of component declaration.
     *
     * @see java.util.Objects#equals(Object,Object)
     *
     * @param   obj   the reference object with which to compare.
     * @return  {@code true} if this record is equal to the
     *          argument; {@code false} otherwise.
     */
    @Override
    public abstract boolean equals(Object obj);

    
Returns a hash code value for the record. Obeys the general contract of Object.hashCode. For records, hashing behavior is constrained by the refined contract of Record.equals, so that any two records created from the same components must have the same hash code. 
See Also:
Implementation Requirements: The implicitly provided implementation returns a hash code value derived by combining appropriate hashes from each component. The precise algorithm used in the implicitly provided implementation is unspecified and is subject to change within the above limits. The resulting integer need not remain consistent from one execution of an application to another execution of the same application, even if the hashes of the component values were to remain consistent in this way. Also, a component of primitive type may contribute its bits to the hash code differently than the hashCode of its primitive wrapper class.
Returns: a hash code value for this record.
/**
     * Returns a hash code value for the record.
     * Obeys the general contract of {@link Object#hashCode Object.hashCode}.
     * For records, hashing behavior is constrained by the refined contract
     * of {@link Record#equals Record.equals}, so that any two records
     * created from the same components must have the same hash code.
     *
     * @implSpec
     * The implicitly provided implementation returns a hash code value derived
     * by combining appropriate hashes from each component.
     * The precise algorithm used in the implicitly provided implementation
     * is unspecified and is subject to change within the above limits.
     * The resulting integer need not remain consistent from one
     * execution of an application to another execution of the same
     * application, even if the hashes of the component values were to
     * remain consistent in this way.  Also, a component of primitive
     * type may contribute its bits to the hash code differently than
     * the {@code hashCode} of its primitive wrapper class.
     *
     * @see     Object#hashCode()
     *
     * @return  a hash code value for this record.
     */
    @Override
    public abstract int hashCode();

    
Returns a string representation of the record. In accordance with the general contract of Object.toString(), the toString method returns a string that "textually represents" this record. The result should be a concise but informative representation that is easy for a person to read. 
 In addition to this general contract, record classes must further participate in the invariant that any two records which are equal must produce equal strings. This invariant is necessarily relaxed in the rare case where corresponding equal component values might fail to produce equal strings for themselves. 
See Also:
Implementation Requirements:
The implicitly provided implementation returns a string which
contains the name of the record class, the names of components
of the record, and string representations of component values,
so as to fulfill the contract of this method.
The precise format produced by this implicitly provided implementation
is subject to change, so the present syntax should not be parsed
by applications to recover record component values.
Returns: a string representation of the object.
/**
     * Returns a string representation of the record.
     * In accordance with the general contract of {@link Object#toString()},
     * the {@code toString} method returns a string that
     * "textually represents" this record. The result should
     * be a concise but informative representation that is easy for a
     * person to read.
     * <p>
     * In addition to this general contract, record classes must further
     * participate in the invariant that any two records which are
     * {@linkplain Record#equals(Object) equal} must produce equal
     * strings.  This invariant is necessarily relaxed in the rare
     * case where corresponding equal component values might fail
     * to produce equal strings for themselves.
     *
     * @implSpec
     * The implicitly provided implementation returns a string which
     * contains the name of the record class, the names of components
     * of the record, and string representations of component values,
     * so as to fulfill the contract of this method.
     * The precise format produced by this implicitly provided implementation
     * is subject to change, so the present syntax should not be parsed
     * by applications to recover record component values.
     *
     * @see     Object#toString()
     *
     * @return  a string representation of the object.
     */
    @Override
    public abstract String toString();
}