/*
 * Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package javax.print;

import javax.print.attribute.Attribute;
import javax.print.attribute.AttributeSet;
import javax.print.attribute.PrintServiceAttribute;
import javax.print.attribute.PrintServiceAttributeSet;
import javax.print.event.PrintServiceAttributeListener;

Interface PrintService is the factory for a DocPrintJob. A PrintService describes the capabilities of a printer and can be queried regarding a printer's supported attributes.

Example:


  DocFlavor flavor = DocFlavor.INPUT_STREAM.POSTSCRIPT;
  PrintRequestAttributeSet aset = new HashPrintRequestAttributeSet();
  aset.add(MediaSizeName.ISO_A4);
  PrintService[] pservices =
                PrintServiceLookup.lookupPrintServices(flavor, aset);
  if (pservices.length > 0) {
      DocPrintJob pj = pservices[0].createPrintJob();
      try {
          FileInputStream fis = new FileInputStream("test.ps");
          Doc doc = new SimpleDoc(fis, flavor, null);
          pj.print(doc, aset);
       } catch (FileNotFoundException fe) {
       } catch (PrintException e) {
       }
  }
  
/** * Interface {@code PrintService} is the factory for a {@code DocPrintJob}. A * {@code PrintService} describes the capabilities of a printer and can be * queried regarding a printer's supported attributes. * <p> * Example: * <pre>{@code * DocFlavor flavor = DocFlavor.INPUT_STREAM.POSTSCRIPT; * PrintRequestAttributeSet aset = new HashPrintRequestAttributeSet(); * aset.add(MediaSizeName.ISO_A4); * PrintService[] pservices = * PrintServiceLookup.lookupPrintServices(flavor, aset); * if (pservices.length > 0) { * DocPrintJob pj = pservices[0].createPrintJob(); * try { * FileInputStream fis = new FileInputStream("test.ps"); * Doc doc = new SimpleDoc(fis, flavor, null); * pj.print(doc, aset); * } catch (FileNotFoundException fe) { * } catch (PrintException e) { * } * } * }</pre> */
public interface PrintService {
Returns a string name for this print service which may be used by applications to request a particular print service. In a suitable context, such as a name service, this name must be unique. In some environments this unique name may be the same as the user friendly printer name defined as the PrinterName attribute.
Returns:name of the service
/** * Returns a string name for this print service which may be used by * applications to request a particular print service. In a suitable * context, such as a name service, this name must be unique. In some * environments this unique name may be the same as the user friendly * printer name defined as the * {@link javax.print.attribute.standard.PrinterName PrinterName} attribute. * * @return name of the service */
public String getName();
Creates and returns a PrintJob capable of handling data from any of the supported document flavors.
Returns:a DocPrintJob object
/** * Creates and returns a {@code PrintJob} capable of handling data from any * of the supported document flavors. * * @return a {@code DocPrintJob} object */
public DocPrintJob createPrintJob();
Registers a listener for events on this PrintService.
Params:
  • listener – a PrintServiceAttributeListener, which monitors the status of a print service
See Also:
/** * Registers a listener for events on this {@code PrintService}. * * @param listener a PrintServiceAttributeListener, which monitors the * status of a print service * @see #removePrintServiceAttributeListener */
public void addPrintServiceAttributeListener( PrintServiceAttributeListener listener);
Removes the print-service listener from this print service. This means the listener is no longer interested in PrintService events.
Params:
  • listener – a PrintServiceAttributeListener object
See Also:
/** * Removes the print-service listener from this print service. This means * the listener is no longer interested in {@code PrintService} events. * * @param listener a {@code PrintServiceAttributeListener} object * @see #addPrintServiceAttributeListener */
public void removePrintServiceAttributeListener( PrintServiceAttributeListener listener);
Obtains this print service's set of printer description attributes giving this Print Service's status. The returned attribute set object is unmodifiable. The returned attribute set object is a "snapshot" of this Print Service's attribute set at the time of the getAttributes() method call: that is, the returned attribute set's contents will not be updated if this print service's attribute set's contents change in the future. To detect changes in attribute values, call getAttributes() again and compare the new attribute set to the previous attribute set; alternatively, register a listener for print service events.
Returns:unmodifiable snapshot of this Print Service's attribute set. May be empty, but not null.
/** * Obtains this print service's set of printer description attributes giving * this Print Service's status. The returned attribute set object is * unmodifiable. The returned attribute set object is a "snapshot" of this * Print Service's attribute set at the time of the {@code getAttributes()} * method call: that is, the returned attribute set's contents will * <i>not</i> be updated if this print service's attribute set's contents * change in the future. To detect changes in attribute values, call * {@code getAttributes()} again and compare the new attribute set to the * previous attribute set; alternatively, register a listener for print * service events. * * @return unmodifiable snapshot of this Print Service's attribute set. May * be empty, but not {@code null}. */
public PrintServiceAttributeSet getAttributes();
Gets the value of the single specified service attribute. This may be useful to clients which only need the value of one attribute and want to minimize overhead.
Params:
  • category – the category of a PrintServiceAttribute supported by this service - may not be null
Type parameters:
  • <T> – the type of the specified service attribute
Throws:
Returns:the value of the supported attribute or null if the attribute is not supported by this service
/** * Gets the value of the single specified service attribute. This may be * useful to clients which only need the value of one attribute and want to * minimize overhead. * * @param <T> the type of the specified service attribute * @param category the category of a {@code PrintServiceAttribute} * supported by this service - may not be {@code null} * @return the value of the supported attribute or {@code null} if the * attribute is not supported by this service * @throws NullPointerException if the category is {@code null} * @throws IllegalArgumentException if {@code category} is not a * {@code Class} that implements interface * {@link PrintServiceAttribute PrintServiceAttribute} */
public <T extends PrintServiceAttribute> T getAttribute(Class<T> category);
Determines the print data formats a client can specify when setting up a job for this PrintService. A print data format is designated by a "doc flavor" (class DocFlavor) consisting of a MIME type plus a print data representation class.

Note that some doc flavors may not be supported in combination with all attributes. Use getUnsupportedAttributes(..) to validate specific combinations.

Returns:array of supported doc flavors, should have at least one element
/** * Determines the print data formats a client can specify when setting up a * job for this {@code PrintService}. A print data format is designated by a * "doc flavor" (class {@link DocFlavor DocFlavor}) consisting of a MIME * type plus a print data representation class. * <p> * Note that some doc flavors may not be supported in combination with all * attributes. Use {@code getUnsupportedAttributes(..)} to validate specific * combinations. * * @return array of supported doc flavors, should have at least one element */
public DocFlavor[] getSupportedDocFlavors();
Determines if this print service supports a specific DocFlavor. This is a convenience method to determine if the DocFlavor would be a member of the result of getSupportedDocFlavors().

Note that some doc flavors may not be supported in combination with all attributes. Use getUnsupportedAttributes(..) to validate specific combinations.

Params:
  • flavor – the DocFlavor to query for support
Throws:
Returns:true if this print service supports the specified DocFlavor; false otherwise
/** * Determines if this print service supports a specific {@code DocFlavor}. * This is a convenience method to determine if the {@code DocFlavor} would * be a member of the result of {@code getSupportedDocFlavors()}. * <p> * Note that some doc flavors may not be supported in combination with all * attributes. Use {@code getUnsupportedAttributes(..)} to validate specific * combinations. * * @param flavor the {@code DocFlavor} to query for support * @return {@code true} if this print service supports the specified * {@code DocFlavor}; {@code false} otherwise * @throws NullPointerException if {@code flavor} is {@code null} */
public boolean isDocFlavorSupported(DocFlavor flavor);
Determines the printing attribute categories a client can specify when setting up a job for this print service. A printing attribute category is designated by a Class that implements interface Attribute. This method returns just the attribute categories that are supported; it does not return the particular attribute values that are supported.

This method returns all the printing attribute categories this print service supports for any possible job. Some categories may not be supported in a particular context (ie for a particular DocFlavor). Use one of the methods that include a DocFlavor to validate the request before submitting it, such as getSupportedAttributeValues(..).

Returns:array of printing attribute categories that the client can specify as a doc-level or job-level attribute in a Print Request. Each element in the array is a Class that implements interface Attribute. The array is empty if no categories are supported.
/** * Determines the printing attribute categories a client can specify when * setting up a job for this print service. A printing attribute category is * designated by a {@code Class} that implements interface * {@link Attribute Attribute}. This method returns just the attribute * <i>categories</i> that are supported; it does not return the particular * attribute <i>values</i> that are supported. * <p> * This method returns all the printing attribute categories this print * service supports for any possible job. Some categories may not be * supported in a particular context (ie for a particular * {@code DocFlavor}). Use one of the methods that include a * {@code DocFlavor} to validate the request before submitting it, such as * {@code getSupportedAttributeValues(..)}. * * @return array of printing attribute categories that the client can * specify as a doc-level or job-level attribute in a Print Request. * Each element in the array is a {@link Class Class} that * implements interface {@link Attribute Attribute}. The array is * empty if no categories are supported. */
public Class<?>[] getSupportedAttributeCategories();
Determines whether a client can specify the given printing attribute category when setting up a job for this print service. A printing attribute category is designated by a Class that implements interface Attribute. This method tells whether the attribute category is supported; it does not tell whether a particular attribute value is supported.

Some categories may not be supported in a particular context (ie for a particular DocFlavor). Use one of the methods which include a DocFlavor to validate the request before submitting it, such as getSupportedAttributeValues(..).

This is a convenience method to determine if the category would be a member of the result of getSupportedAttributeCategories().

Params:
  • category – printing attribute category to test. It must be a Class that implements interface Attribute.
Throws:
Returns:true if this print service supports specifying a doc-level or job-level attribute in category in a Print Request; false if it doesn't
/** * Determines whether a client can specify the given printing attribute * category when setting up a job for this print service. A printing * attribute category is designated by a {@code Class} that implements * interface {@link Attribute Attribute}. This method * tells whether the attribute <i>category</i> is supported; it does not * tell whether a particular attribute <i>value</i> is supported. * <p> * Some categories may not be supported in a particular context (ie for a * particular {@code DocFlavor}). Use one of the methods which include a * {@code DocFlavor} to validate the request before submitting it, such as * {@code getSupportedAttributeValues(..)}. * <p> * This is a convenience method to determine if the category would be a * member of the result of {@code getSupportedAttributeCategories()}. * * @param category printing attribute category to test. It must be a * {@code Class} that implements interface * {@link Attribute Attribute}. * @return {@code true} if this print service supports specifying a * doc-level or job-level attribute in {@code category} in a Print * Request; {@code false} if it doesn't * @throws NullPointerException if {@code category} is {@code null} * @throws IllegalArgumentException if {@code category} is not a * {@code Class} that implements interface * {@link Attribute Attribute} */
public boolean isAttributeCategorySupported(Class<? extends Attribute> category);
Determines this print service's default printing attribute value in the given category. A printing attribute value is an instance of a class that implements interface Attribute. If a client sets up a print job and does not specify any attribute value in the given category, this Print Service will use the default attribute value instead.

Some attributes may not be supported in a particular context (ie for a particular DocFlavor). Use one of the methods that include a DocFlavor to validate the request before submitting it, such as getSupportedAttributeValues(..).

Not all attributes have a default value. For example the service will not have a default value for RequestingUser i.e. a null return for a supported category means there is no service default value for that category. Use the isAttributeCategorySupported(Class) method to distinguish these cases.

Params:
  • category – printing attribute category for which the default attribute value is requested. It must be a Class that implements interface Attribute.
Throws:
Returns:default attribute value for category, or null if this Print Service does not support specifying a doc-level or job-level attribute in category in a Print Request, or the service does not have a default value for this attribute
/** * Determines this print service's default printing attribute value in the * given category. A printing attribute value is an instance of a class that * implements interface {@link Attribute Attribute}. If a client sets up a * print job and does not specify any attribute value in the given category, * this Print Service will use the default attribute value instead. * <p> * Some attributes may not be supported in a particular context (ie for a * particular {@code DocFlavor}). Use one of the methods that include a * {@code DocFlavor} to validate the request before submitting it, such as * {@code getSupportedAttributeValues(..)}. * <p> * Not all attributes have a default value. For example the service will not * have a default value for {@code RequestingUser} i.e. a {@code null} * return for a supported category means there is no service default value * for that category. Use the {@code isAttributeCategorySupported(Class)} * method to distinguish these cases. * * @param category printing attribute category for which the default * attribute value is requested. It must be a {@link Class Class} * that implements interface {@link Attribute Attribute}. * @return default attribute value for {@code category}, or {@code null} if * this Print Service does not support specifying a doc-level or * job-level attribute in {@code category} in a Print Request, or * the service does not have a default value for this attribute * @throws NullPointerException if {@code category} is {@code null} * @throws IllegalArgumentException if {@code category} is not a * {@link Class Class} that implements interface * {@link Attribute Attribute} */
public Object getDefaultAttributeValue(Class<? extends Attribute> category);
Determines the printing attribute values a client can specify in the given category when setting up a job for this print service. A printing attribute value is an instance of a class that implements interface Attribute.

If flavor is null and attributes is null or is an empty set, this method returns all the printing attribute values this Print Service supports for any possible job. If flavor is not null or attributes is not an empty set, this method returns just the printing attribute values that are compatible with the given doc flavor and/or set of attributes. That is, a null return value may indicate that specifying this attribute is incompatible with the specified DocFlavor. Also if DocFlavor is not null it must be a flavor supported by this PrintService, else IllegalArgumentException will be thrown.

If the attributes parameter contains an Attribute whose category is the same as the category parameter, the service must ignore this attribute in the AttributeSet.

DocAttributes which are to be specified on the Doc must be included in this set to accurately represent the context.

This method returns an Object because different printing attribute categories indicate the supported attribute values in different ways. The documentation for each printing attribute in package javax.print.attribute.standard describes how each attribute indicates its supported values. Possible ways of indicating support include:

  • Return a single instance of the attribute category to indicate that any value is legal -- used, for example, by an attribute whose value is an arbitrary text string. (The value of the returned attribute object is irrelevant.)
  • Return an array of one or more instances of the attribute category, containing the legal values -- used, for example, by an attribute with a list of enumerated values. The type of the array is an array of the specified attribute category type as returned by its getCategory(Class).
  • Return a single object (of some class other than the attribute category) that indicates bounds on the legal values -- used, for example, by an integer-valued attribute that must lie within a certain range.
Params:
  • category – printing attribute category to test. It must be a Class that implements interface Attribute.
  • flavor – doc flavor for a supposed job, or null
  • attributes – set of printing attributes for a supposed job (both job-level attributes and document-level attributes), or null
Throws:
Returns:object indicating supported values for category, or null if this Print Service does not support specifying a doc-level or job-level attribute in category in a Print Request
/** * Determines the printing attribute values a client can specify in the * given category when setting up a job for this print service. A printing * attribute value is an instance of a class that implements interface * {@link Attribute Attribute}. * <p> * If {@code flavor} is {@code null} and {@code attributes} is {@code null} * or is an empty set, this method returns all the printing attribute values * this Print Service supports for any possible job. If {@code flavor} is not * {@code null} or {@code attributes} is not an empty set, this method * returns just the printing attribute values that are compatible with the * given doc flavor and/or set of attributes. That is, a {@code null} return * value may indicate that specifying this attribute is incompatible with * the specified DocFlavor. Also if {@code DocFlavor} is not {@code null} it * must be a flavor supported by this {@code PrintService}, else * {@code IllegalArgumentException} will be thrown. * <p> * If the {@code attributes} parameter contains an {@code Attribute} whose * category is the same as the {@code category} parameter, the service must * ignore this attribute in the {@code AttributeSet}. * <p> * {@code DocAttribute}s which are to be specified on the {@code Doc} must * be included in this set to accurately represent the context. * <p> * This method returns an {@code Object} because different printing * attribute categories indicate the supported attribute values in different * ways. The documentation for each printing attribute in package * {@link javax.print.attribute.standard javax.print.attribute.standard} * describes how each attribute indicates its supported values. Possible * ways of indicating support include: * <ul> * <li>Return a single instance of the attribute category to indicate that * any value is legal -- used, for example, by an attribute whose value is * an arbitrary text string. (The value of the returned attribute object * is irrelevant.) * <li>Return an array of one or more instances of the attribute category, * containing the legal values -- used, for example, by an attribute with * a list of enumerated values. The type of the array is an array of the * specified attribute category type as returned by its * {@code getCategory(Class)}. * <li>Return a single object (of some class other than the attribute * category) that indicates bounds on the legal values -- used, for * example, by an integer-valued attribute that must lie within a certain * range. * </ul> * * @param category printing attribute category to test. It must be a * {@link Class Class} that implements interface * {@link Attribute Attribute}. * @param flavor doc flavor for a supposed job, or {@code null} * @param attributes set of printing attributes for a supposed job (both * job-level attributes and document-level attributes), or * {@code null} * @return object indicating supported values for {@code category}, or * {@code null} if this Print Service does not support specifying a * doc-level or job-level attribute in {@code category} in a Print * Request * @throws NullPointerException if {@code category} is {@code null} * @throws IllegalArgumentException if {@code category} is not a * {@link Class Class} that implements interface * {@link Attribute Attribute}, or {@code DocFlavor} is not * supported by this service */
public Object getSupportedAttributeValues(Class<? extends Attribute> category, DocFlavor flavor, AttributeSet attributes);
Determines whether a client can specify the given printing attribute value when setting up a job for this Print Service. A printing attribute value is an instance of a class that implements interface Attribute.

If flavor is null and attributes is null or is an empty set, this method tells whether this Print Service supports the given printing attribute value for some possible combination of doc flavor and set of attributes. If flavor is not null or attributes is not an empty set, this method tells whether this Print Service supports the given printing attribute value in combination with the given doc flavor and/or set of attributes.

Also if DocFlavor is not null it must be a flavor supported by this PrintService, else IllegalArgumentException will be thrown.

DocAttributes which are to be specified on the Doc must be included in this set to accurately represent the context.

This is a convenience method to determine if the value would be a member of the result of getSupportedAttributeValues(...).

Params:
  • attrval – printing attribute value to test
  • flavor – doc flavor for a supposed job, or null
  • attributes – set of printing attributes for a supposed job (both job-level attributes and document-level attributes), or null
Throws:
Returns:true if this Print Service supports specifying attrval as a doc-level or job-level attribute in a Print Request, false if it doesn't
/** * Determines whether a client can specify the given printing attribute * value when setting up a job for this Print Service. A printing attribute * value is an instance of a class that implements interface * {@link Attribute Attribute}. * <p> * If {@code flavor} is {@code null} and {@code attributes} is {@code null} * or is an empty set, this method tells whether this Print Service supports * the given printing attribute value for some possible combination of doc * flavor and set of attributes. If {@code flavor} is not {@code null} or * {@code attributes} is not an empty set, this method tells whether this * Print Service supports the given printing attribute value in combination * with the given doc flavor and/or set of attributes. * <p> * Also if {@code DocFlavor} is not {@code null} it must be a flavor * supported by this {@code PrintService}, else * {@code IllegalArgumentException} will be thrown. * <p> * {@code DocAttribute}s which are to be specified on the {@code Doc} must * be included in this set to accurately represent the context. * <p> * This is a convenience method to determine if the value would be a member * of the result of {@code getSupportedAttributeValues(...)}. * * @param attrval printing attribute value to test * @param flavor doc flavor for a supposed job, or {@code null} * @param attributes set of printing attributes for a supposed job (both * job-level attributes and document-level attributes), or * {@code null} * @return {@code true} if this Print Service supports specifying * {@code attrval} as a doc-level or job-level attribute in a Print * Request, {@code false} if it doesn't * @throws NullPointerException if {@code attrval} is {@code null} * @throws IllegalArgumentException if flavor is not supported by this * {@code PrintService} */
public boolean isAttributeValueSupported(Attribute attrval, DocFlavor flavor, AttributeSet attributes);
Identifies the attributes that are unsupported for a print request in the context of a particular DocFlavor. This method is useful for validating a potential print job and identifying the specific attributes which cannot be supported. It is important to supply only a supported DocFlavor or an IllegalArgumentException will be thrown. If the return value from this method is null, all attributes are supported.

DocAttributes which are to be specified on the Doc must be included in this set to accurately represent the context.

If the return value is non-null, all attributes in the returned set are unsupported with this DocFlavor. The returned set does not distinguish attribute categories that are unsupported from unsupported attribute values.

A supported print request can then be created by removing all unsupported attributes from the original attribute set, except in the case that the DocFlavor is unsupported.

If any attributes are unsupported only because they are in conflict with other attributes then it is at the discretion of the service to select the attribute(s) to be identified as the cause of the conflict.

Use isDocFlavorSupported() to verify that a DocFlavor is supported before calling this method.

Params:
  • flavor – doc flavor to test, or null
  • attributes – set of printing attributes for a supposed job (both job-level attributes and document-level attributes), or null
Throws:
Returns:null if this Print Service supports the print request specification, else the unsupported attributes
/** * Identifies the attributes that are unsupported for a print request in the * context of a particular {@code DocFlavor}. This method is useful for * validating a potential print job and identifying the specific attributes * which cannot be supported. It is important to supply only a supported * {@code DocFlavor} or an {@code IllegalArgumentException} will be thrown. * If the return value from this method is {@code null}, all attributes are * supported. * <p> * {@code DocAttribute}s which are to be specified on the {@code Doc} must * be included in this set to accurately represent the context. * <p> * If the return value is {@code non-null}, all attributes in the returned * set are unsupported with this {@code DocFlavor}. The returned set does * not distinguish attribute categories that are unsupported from * unsupported attribute values. * <p> * A supported print request can then be created by removing all unsupported * attributes from the original attribute set, except in the case that the * {@code DocFlavor} is unsupported. * <p> * If any attributes are unsupported only because they are in conflict with * other attributes then it is at the discretion of the service to select * the attribute(s) to be identified as the cause of the conflict. * <p> * Use {@code isDocFlavorSupported()} to verify that a {@code DocFlavor} is * supported before calling this method. * * @param flavor doc flavor to test, or {@code null} * @param attributes set of printing attributes for a supposed job (both * job-level attributes and document-level attributes), or * {@code null} * @return {@code null} if this Print Service supports the print request * specification, else the unsupported attributes * @throws IllegalArgumentException if {@code flavor} is not supported by * this {@code PrintService} */
public AttributeSet getUnsupportedAttributes(DocFlavor flavor, AttributeSet attributes);
Returns a factory for UI components which allow users to interact with the service in various roles. Services which do not provide any UI should return null. Print Services which do provide UI but want to be supported in an environment with no UI support should ensure that the factory is not initialised unless the application calls this method to obtain the factory. See ServiceUIFactory for more information.
Returns:null or a factory for UI components
/** * Returns a factory for UI components which allow users to interact with * the service in various roles. Services which do not provide any UI should * return {@code null}. Print Services which do provide UI but want to be * supported in an environment with no UI support should ensure that the * factory is not initialised unless the application calls this method to * obtain the factory. See {@code ServiceUIFactory} for more information. * * @return {@code null} or a factory for UI components */
public ServiceUIFactory getServiceUIFactory();
Determines if two services are referring to the same underlying service. Objects encapsulating a print service may not exhibit equality of reference even though they refer to the same underlying service.

Clients should call this method to determine if two services are referring to the same underlying service.

Services must implement this method and return true only if the service objects being compared may be used interchangeably by the client. Services are free to return the same object reference to an underlying service if that, but clients must not depend on equality of reference.

Params:
  • obj – the reference object with which to compare
Returns:true if this service is the same as the obj argument, false otherwise
/** * Determines if two services are referring to the same underlying service. * Objects encapsulating a print service may not exhibit equality of * reference even though they refer to the same underlying service. * <p> * Clients should call this method to determine if two services are * referring to the same underlying service. * <p> * Services must implement this method and return {@code true} only if the * service objects being compared may be used interchangeably by the client. * Services are free to return the same object reference to an underlying * service if that, but clients must not depend on equality of reference. * * @param obj the reference object with which to compare * @return {@code true} if this service is the same as the obj argument, * {@code false} otherwise */
public boolean equals(Object obj);
This method should be implemented consistently with equals(Object).
Returns:hash code of this object
/** * This method should be implemented consistently with * {@code equals(Object)}. * * @return hash code of this object */
public int hashCode(); }