Internal representation of map fields in generated messages.
This class supports accessing the map field as a Map to be used in generated API and
also supports accessing the field as a List to be used in reflection API. It keeps track
of where the data is currently stored and do necessary conversions between map and list.
This class is a protobuf implementation detail. Users shouldn't use this class directly.
THREAD-SAFETY NOTE: Read-only access is thread-safe. Users can call getMap() and getList()
concurrently in multiple threads. If write-access is needed, all access must be synchronized.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-07 UTC."],[],[],null,["# Class MapField<K,V> (3.19.4)\n\n public class MapField\u003cK,V\u003e implements MutabilityOracle\n\nInternal representation of map fields in generated messages.\n\nThis class supports accessing the map field as a [Map](https://docs.oracle.com/javase/8/docs/api/java/util/Map.html) to be used in generated API and\nalso supports accessing the field as a [List](https://docs.oracle.com/javase/8/docs/api/java/util/List.html) to be used in reflection API. It keeps track\nof where the data is currently stored and do necessary conversions between map and list.\n\nThis class is a protobuf implementation detail. Users shouldn't use this class directly.\n\nTHREAD-SAFETY NOTE: Read-only access is thread-safe. Users can call getMap() and getList()\nconcurrently in multiple threads. If write-access is needed, all access must be synchronized. \n\nInheritance\n-----------\n\n[Object](https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html) \\\u003e MapField\\\u003cK,V\\\u003e \n\nImplements\n----------\n\ncom.google.protobuf.MutabilityOracle \n\nInherited Members\n-----------------\n\n[Object.clone()](https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#clone--) \n[Object.equals(Object)](https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#equals-java.lang.Object-) \n[Object.finalize()](https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#finalize--) \n[Object.getClass()](https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#getClass--) \n[Object.hashCode()](https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#hashCode--) \n[Object.notify()](https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#notify--) \n[Object.notifyAll()](https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#notifyAll--) \n[Object.toString()](https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#toString--) \n[Object.wait()](https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait--) \n[Object.wait(long)](https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-) \n[Object.wait(long,int)](https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-int-)\n\nStatic Methods\n--------------\n\n### \\\u003cK,V\\\u003eemptyMapField(MapEntry\\\u003cK,V\\\u003e defaultEntry)\n\n public static MapField\u003cK,V\u003e \u003cK,V\u003eemptyMapField(MapEntry\u003cK,V\u003e defaultEntry)\n\nReturns an immutable empty MapField.\n\n### \\\u003cK,V\\\u003enewMapField(MapEntry\\\u003cK,V\\\u003e defaultEntry)\n\n public static MapField\u003cK,V\u003e \u003cK,V\u003enewMapField(MapEntry\u003cK,V\u003e defaultEntry)\n\nCreates a new mutable empty MapField.\n\nMethods\n-------\n\n### clear()\n\n public void clear()\n\n### copy()\n\n public MapField\u003cK,V\u003e copy()\n\nReturns a deep copy of this MapField.\n\n### ensureMutable()\n\n public void ensureMutable()\n\nThrows an UnsupportedOperationException if not mutable.\n\n### equals(Object object)\n\n public boolean equals(Object object)\n\n**Overrides** \n[Object.equals(Object)](https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#equals-java.lang.Object-)\n\n### getMap()\n\n public Map\u003cK,V\u003e getMap()\n\nReturns the content of this MapField as a read-only Map.\n\n### getMutableMap()\n\n public Map\u003cK,V\u003e getMutableMap()\n\nGets a mutable Map view of this MapField.\n\n### hashCode()\n\n public int hashCode()\n\n**Overrides** \n[Object.hashCode()](https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#hashCode--)\n\n### isMutable()\n\n public boolean isMutable()\n\nReturns whether this field can be modified.\n\n### makeImmutable()\n\n public void makeImmutable()\n\nMakes this list immutable. All subsequent modifications will throw an UnsupportedOperationException.\n\n### mergeFrom(MapField\\\u003cK,V\\\u003e other)\n\n public void mergeFrom(MapField\u003cK,V\u003e other)"]]
