001/* 002 * Copyright 2001-2005 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 */ 016package org.joda.time.field; 017 018import java.io.Serializable; 019import org.joda.time.DurationField; 020import org.joda.time.DurationFieldType; 021 022/** 023 * BaseDurationField provides the common behaviour for DurationField 024 * implementations. 025 * <p> 026 * This class should generally not be used directly by API users. The 027 * DurationField class should be used when different kinds of DurationField 028 * objects are to be referenced. 029 * <p> 030 * BaseDurationField is thread-safe and immutable, and its subclasses must 031 * be as well. 032 * 033 * @author Brian S O'Neill 034 * @see DecoratedDurationField 035 * @since 1.0 036 */ 037public abstract class BaseDurationField extends DurationField implements Serializable { 038 039 /** Serialization lock. */ 040 private static final long serialVersionUID = -2554245107589433218L; 041 042 /** A desriptive name for the field. */ 043 private final DurationFieldType iType; 044 045 protected BaseDurationField(DurationFieldType type) { 046 super(); 047 if (type == null) { 048 throw new IllegalArgumentException("The type must not be null"); 049 } 050 iType = type; 051 } 052 053 public final DurationFieldType getType() { 054 return iType; 055 } 056 057 public final String getName() { 058 return iType.getName(); 059 } 060 061 /** 062 * @return true always 063 */ 064 public final boolean isSupported() { 065 return true; 066 } 067 068 //------------------------------------------------------------------------ 069 /** 070 * Get the value of this field from the milliseconds, which is approximate 071 * if this field is imprecise. 072 * 073 * @param duration the milliseconds to query, which may be negative 074 * @return the value of the field, in the units of the field, which may be 075 * negative 076 */ 077 public int getValue(long duration) { 078 return FieldUtils.safeToInt(getValueAsLong(duration)); 079 } 080 081 /** 082 * Get the value of this field from the milliseconds, which is approximate 083 * if this field is imprecise. 084 * 085 * @param duration the milliseconds to query, which may be negative 086 * @return the value of the field, in the units of the field, which may be 087 * negative 088 */ 089 public long getValueAsLong(long duration) { 090 return duration / getUnitMillis(); 091 } 092 093 /** 094 * Get the value of this field from the milliseconds relative to an 095 * instant. 096 * 097 * <p>If the milliseconds is positive, then the instant is treated as a 098 * "start instant". If negative, the instant is treated as an "end 099 * instant". 100 * 101 * <p>The default implementation returns 102 * <code>Utils.safeToInt(getAsLong(millisDuration, instant))</code>. 103 * 104 * @param duration the milliseconds to query, which may be negative 105 * @param instant the start instant to calculate relative to 106 * @return the value of the field, in the units of the field, which may be 107 * negative 108 */ 109 public int getValue(long duration, long instant) { 110 return FieldUtils.safeToInt(getValueAsLong(duration, instant)); 111 } 112 113 /** 114 * Get the millisecond duration of this field from its value, which is 115 * approximate if this field is imprecise. 116 * 117 * @param value the value of the field, which may be negative 118 * @return the milliseconds that the field represents, which may be 119 * negative 120 */ 121 public long getMillis(int value) { 122 return value * getUnitMillis(); // safe 123 } 124 125 /** 126 * Get the millisecond duration of this field from its value, which is 127 * approximate if this field is imprecise. 128 * 129 * @param value the value of the field, which may be negative 130 * @return the milliseconds that the field represents, which may be 131 * negative 132 */ 133 public long getMillis(long value) { 134 return FieldUtils.safeMultiply(value, getUnitMillis()); 135 } 136 137 // Calculation API 138 //------------------------------------------------------------------------ 139 public int getDifference(long minuendInstant, long subtrahendInstant) { 140 return FieldUtils.safeToInt(getDifferenceAsLong(minuendInstant, subtrahendInstant)); 141 } 142 143 //------------------------------------------------------------------------ 144 public int compareTo(Object durationField) { 145 DurationField otherField = (DurationField) durationField; 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}