Java tutorial
/** * Copyright (C) 2014 - present by OpenGamma Inc. and the OpenGamma group of companies * * Please see distribution for license. */ package com.opengamma.strata.collect.io; import java.util.Map; import java.util.Map.Entry; import com.google.common.base.MoreObjects; import com.google.common.collect.ArrayListMultimap; import com.google.common.collect.ImmutableList; import com.google.common.collect.ImmutableListMultimap; import com.google.common.collect.ImmutableMap; import com.google.common.collect.ImmutableSet; import com.google.common.collect.ListMultimap; import com.google.common.collect.Multimap; import com.opengamma.strata.collect.ArgChecker; /** * A map of key-value properties. * <p> * This class represents a map of key to value. * Multiple values may be associated with each key. * <p> * This class is generally created by reading an INI or properties file. * See {@link IniFile} and {@link PropertiesFile}. */ public final class PropertySet { // this class is common between IniFile and PropertiesFile /** * The empty instance. */ private static final PropertySet EMPTY = new PropertySet(ImmutableListMultimap.of()); /** * The key-value pairs. */ private final ImmutableListMultimap<String, String> keyValueMap; //------------------------------------------------------------------------- /** * Obtains an empty property set. * <p> * The result contains no properties. * * @return an empty property set */ public static PropertySet empty() { return EMPTY; } /** * Obtains an instance from a map. * <p> * The returned instance will have one value for each key. * * @param keyValues the key-values to create the instance with * @return the property set */ public static PropertySet of(Map<String, String> keyValues) { ArgChecker.notNull(keyValues, "keyValues"); ImmutableListMultimap.Builder<String, String> builder = ImmutableListMultimap.builder(); for (Entry<String, String> entry : keyValues.entrySet()) { builder.put(entry); } return new PropertySet(builder.build()); } /** * Obtains an instance from a map allowing for multiple values for each key. * <p> * The returned instance may have more than one value for each key. * * @param keyValues the key-values to create the instance with * @return the property set */ public static PropertySet of(Multimap<String, String> keyValues) { ArgChecker.notNull(keyValues, "keyValues"); return new PropertySet(ImmutableListMultimap.copyOf(keyValues)); } //------------------------------------------------------------------------- /** * Restricted constructor. * * @param keyValues the key-value pairs */ private PropertySet(ImmutableListMultimap<String, String> keyValues) { this.keyValueMap = keyValues; } //------------------------------------------------------------------------- /** * Returns the set of keys of this property set. * <p> * The iteration order of the map matches that of the input data. * * @return the set of keys */ public ImmutableSet<String> keys() { return ImmutableSet.copyOf(keyValueMap.keySet()); } /** * Returns the property set as a multimap. * <p> * The iteration order of the map matches that of the input data. * * @return the key-value map */ public ImmutableListMultimap<String, String> asMultimap() { return keyValueMap; } /** * Returns the property set as a map, throwing an exception if any key has multiple values. * <p> * The iteration order of the map matches that of the input data. * * @return the key-value map */ public ImmutableMap<String, String> asMap() { ImmutableMap.Builder<String, String> builder = ImmutableMap.builder(); for (String key : keys()) { builder.put(key, value(key)); } return builder.build(); } //------------------------------------------------------------------------- /** * Checks if this property set is empty. * * @return true if the set is empty */ public boolean isEmpty() { return keyValueMap.isEmpty(); } /** * Checks if this property set contains the specified key. * * @param key the key name * @return true if the key exists */ public boolean contains(String key) { ArgChecker.notNull(key, "key"); return keyValueMap.containsKey(key); } /** * Gets a single value from this property set. * <p> * This returns the value associated with the specified key. * If more than one value, or no value, is associated with the key an exception is thrown. * * @param key the key name * @return the value * @throws IllegalArgumentException if the key does not exist, or if more than one value is associated */ public String value(String key) { ArgChecker.notNull(key, "key"); ImmutableList<String> values = keyValueMap.get(key); if (values.size() == 0) { throw new IllegalArgumentException("Unknown key: " + key); } if (values.size() > 1) { throw new IllegalArgumentException("Multiple values for key: " + key); } return values.get(0); } /** * Gets the list of values associated with the specified key. * <p> * A key-values instance may contain multiple values for each key. * This method returns that list of values. * The iteration order of the map matches that of the input data. * The returned list may be empty. * * @param key the key name * @return the list of values associated with the key */ public ImmutableList<String> valueList(String key) { ArgChecker.notNull(key, "key"); return MoreObjects.firstNonNull(keyValueMap.get(key), ImmutableList.<String>of()); } //------------------------------------------------------------------------- /** * Combines this property set with another. * <p> * The specified property set takes precedence. * * @param other the other property set * @return the combined property set */ public PropertySet combinedWith(PropertySet other) { ArgChecker.notNull(other, "other"); if (other.isEmpty()) { return this; } if (isEmpty()) { return other; } ListMultimap<String, String> map = ArrayListMultimap.create(keyValueMap); for (String key : other.asMultimap().keySet()) { map.removeAll(key); map.putAll(key, other.valueList(key)); } return new PropertySet(ImmutableListMultimap.copyOf(map)); } //------------------------------------------------------------------------- /** * Checks if this property set equals another. * <p> * The comparison checks the content. * * @param obj the other section, null returns false * @return true if equal */ @Override public boolean equals(Object obj) { if (obj == this) { return true; } if (obj instanceof PropertySet) { return keyValueMap.equals(((PropertySet) obj).keyValueMap); } return false; } /** * Returns a suitable hash code for the property set. * * @return the hash code */ @Override public int hashCode() { return keyValueMap.hashCode(); } /** * Returns a string describing the property set. * * @return the descriptive string */ @Override public String toString() { return keyValueMap.toString(); } }