Comparing two hashmaps for equal values and same key sets

Question

How can I best compare two HashMaps  if I want to find out if none of them contains different keys than the other  and if the values of that keys match each other   Map lt objA  objB gt  mapA   new HashMap lt objA  objB gt     mapA put  A    1    mapA put  B    2     Map lt objA  objB gt  mapB   new HashMap lt objA  objB gt     mapB put  D    4    mapB put  A    1      When comparing A with B  it should fail due to different keys B and D   How could I best compare non-sorted hashmaps

User · Answer

if you have two maps lets say map1 and map2 then using java8 Streams we can compare maps using code below But it is recommended to use equals rather then    or      boolean b   map1 entrySet   stream   filter value - gt               map2 entrySet   stream   anyMatch value1 - gt                value1 getKey   equals value getKey     amp  amp     value1 getValue   equals value getValue       findAny   isPresent         System out println  comparison    b

User · Answer

JAVA 8 using streams      public static void main String args                  Map lt Integer  Boolean gt  map   new HashMap lt Integer  Boolean gt             map put 100  true           map put 1011  false           map put 1022  false            Map lt Integer  Boolean gt  map1   new HashMap lt Integer  Boolean gt             map1 put 100  false           map1 put 101  false           map1 put 102  false            boolean b   map entrySet   stream   filter value - gt  map1 entrySet   stream   anyMatch value1 - gt   value1 getKey      value getKey    amp  amp  value1 getValue      value getValue      findAny   isPresent            System out println b

User · Answer

public boolean compareMap Map lt String  String gt  map1  Map lt String  String gt  map2         if  map1    null    map2    null          return false       for  String ch1   map1 keySet              if   map1 get ch1  equalsIgnoreCase map2 get ch1                return false             for  String ch2   map2 keySet              if   map2 get ch2  equalsIgnoreCase map1 get ch2                return false              return true

User · Answer

Simply use    mapA equals mapB       Compares the specified object with this map for equality  Returns true   if the given object is also a map and the two maps represent the same   mappings

User · Answer

Make an equals check on the keySet   of both HashMaps   NOTE   If your Map contains String keys then it is no problem  but if your Map contains objA type keys then you need to make sure that your class objA implements equals

User · Answer

Compare every key in mapB against the counterpart in mapA  Then check if there is any key in mapA not existing in mapB  public boolean mapsAreEqual Map lt String  String gt  mapA  Map lt String  String gt  mapB         try          for  String k   mapB keySet                          if   mapA get k  equals mapB get k                      return false                                   for  String y   mapA keySet                          if   mapB containsKey y                     return false                                 catch  NullPointerException np            return false            return true

[java] Comparing two hashmaps for equal values and same key sets?

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