001/* 002 * (C) Copyright 2014 Nuxeo SA (http://nuxeo.com/) and others. 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * http://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 * 016 * Contributors: 017 * Nicolas Chapurlat <nchapurlat@nuxeo.com> 018 */ 019 020package org.nuxeo.ecm.core.schema.types.constraints; 021 022import java.io.Serializable; 023import java.util.HashMap; 024import java.util.Map; 025 026/** 027 * This constraint ensure some object is not null. 028 * <p> 029 * This class is a singleton. Use {@link #get()} to get the singleton. 030 * </p> 031 * 032 * @since 7.1 033 * @author <a href="mailto:nc@nuxeo.com">Nicolas Chapurlat</a> 034 */ 035public class NotNullConstraint extends AbstractConstraint { 036 037 private static final long serialVersionUID = 1L; 038 039 private static final String NAME = "NotNullConstraint"; 040 041 // Lazy ang thread safe singleton instance. 042 private static class Holder { 043 private static final NotNullConstraint INSTANCE = new NotNullConstraint(); 044 } 045 046 private NotNullConstraint() { 047 } 048 049 public static NotNullConstraint get() { 050 return Holder.INSTANCE; 051 } 052 053 @Override 054 public boolean validate(Object object) { 055 return object != null; 056 } 057 058 /** 059 * Here, value is : <br> 060 * name = {@value #NAME}. <br> 061 * parameters is empty 062 */ 063 @Override 064 public Description getDescription() { 065 Map<String, Serializable> params = new HashMap<String, Serializable>(); 066 return new Description(NotNullConstraint.NAME, params); 067 } 068 069 @Override 070 public int hashCode() { 071 return NotNullConstraint.class.hashCode(); 072 } 073 074 @Override 075 public boolean equals(Object obj) { 076 return obj != null && obj instanceof NotNullConstraint; 077 } 078}