001 /* 002 * Copyright 2001-2009 Stephen Colebourne 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 package org.joda.time.field; 017 018 import java.io.Serializable; 019 020 import org.joda.time.DurationField; 021 import org.joda.time.DurationFieldType; 022 023 /** 024 * BaseDurationField provides the common behaviour for DurationField 025 * implementations. 026 * <p> 027 * This class should generally not be used directly by API users. The 028 * DurationField class should be used when different kinds of DurationField 029 * objects are to be referenced. 030 * <p> 031 * BaseDurationField is thread-safe and immutable, and its subclasses must 032 * be as well. 033 * 034 * @author Brian S O'Neill 035 * @see DecoratedDurationField 036 * @since 1.0 037 */ 038 public abstract class BaseDurationField extends DurationField implements Serializable { 039 040 /** Serialization lock. */ 041 private static final long serialVersionUID = -2554245107589433218L; 042 043 /** A desriptive name for the field. */ 044 private final DurationFieldType iType; 045 046 protected BaseDurationField(DurationFieldType type) { 047 super(); 048 if (type == null) { 049 throw new IllegalArgumentException("The type must not be null"); 050 } 051 iType = type; 052 } 053 054 public final DurationFieldType getType() { 055 return iType; 056 } 057 058 public final String getName() { 059 return iType.getName(); 060 } 061 062 /** 063 * @return true always 064 */ 065 public final boolean isSupported() { 066 return true; 067 } 068 069 //------------------------------------------------------------------------ 070 /** 071 * Get the value of this field from the milliseconds, which is approximate 072 * if this field is imprecise. 073 * 074 * @param duration the milliseconds to query, which may be negative 075 * @return the value of the field, in the units of the field, which may be 076 * negative 077 */ 078 public int getValue(long duration) { 079 return FieldUtils.safeToInt(getValueAsLong(duration)); 080 } 081 082 /** 083 * Get the value of this field from the milliseconds, which is approximate 084 * if this field is imprecise. 085 * 086 * @param duration the milliseconds to query, which may be negative 087 * @return the value of the field, in the units of the field, which may be 088 * negative 089 */ 090 public long getValueAsLong(long duration) { 091 return duration / getUnitMillis(); 092 } 093 094 /** 095 * Get the value of this field from the milliseconds relative to an 096 * instant. 097 * 098 * <p>If the milliseconds is positive, then the instant is treated as a 099 * "start instant". If negative, the instant is treated as an "end 100 * instant". 101 * 102 * <p>The default implementation returns 103 * <code>Utils.safeToInt(getAsLong(millisDuration, instant))</code>. 104 * 105 * @param duration the milliseconds to query, which may be negative 106 * @param instant the start instant to calculate relative to 107 * @return the value of the field, in the units of the field, which may be 108 * negative 109 */ 110 public int getValue(long duration, long instant) { 111 return FieldUtils.safeToInt(getValueAsLong(duration, instant)); 112 } 113 114 /** 115 * Get the millisecond duration of this field from its value, which is 116 * approximate if this field is imprecise. 117 * 118 * @param value the value of the field, which may be negative 119 * @return the milliseconds that the field represents, which may be 120 * negative 121 */ 122 public long getMillis(int value) { 123 return value * getUnitMillis(); // safe 124 } 125 126 /** 127 * Get the millisecond duration of this field from its value, which is 128 * approximate if this field is imprecise. 129 * 130 * @param value the value of the field, which may be negative 131 * @return the milliseconds that the field represents, which may be 132 * negative 133 */ 134 public long getMillis(long value) { 135 return FieldUtils.safeMultiply(value, getUnitMillis()); 136 } 137 138 // Calculation API 139 //------------------------------------------------------------------------ 140 public int getDifference(long minuendInstant, long subtrahendInstant) { 141 return FieldUtils.safeToInt(getDifferenceAsLong(minuendInstant, subtrahendInstant)); 142 } 143 144 //------------------------------------------------------------------------ 145 public int compareTo(DurationField otherField) { 146 long otherMillis = otherField.getUnitMillis(); 147 long thisMillis = getUnitMillis(); 148 // cannot do (thisMillis - otherMillis) as can overflow 149 if (thisMillis == otherMillis) { 150 return 0; 151 } 152 if (thisMillis < otherMillis) { 153 return -1; 154 } else { 155 return 1; 156 } 157 } 158 159 /** 160 * Get a suitable debug string. 161 * 162 * @return debug string 163 */ 164 public String toString() { 165 return "DurationField[" + getName() + ']'; 166 } 167 168 }