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Checking map content on another map in java

I need to write a small piece of code where I need to check the contents of the map (key value), if it exists on another map, remove it from the map

For instance,

Map1:

1=>obj1
2=>obj21
3=>obj3 
4=>obj4

Other Map2:

10=>obj10
20=>obj20
2=>obj2
30=>obj30
3=>obj3

Fun result (Map1, Map2) after executing it has the following output

map2:

10=>obj10
2=>obj2
20=>obj20
30=>obj30

Iterates over the smaller map and checks the contents (key, value) iterates over the smaller map and checks the key and contents in the larger map the most efficient workaround.

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4 answers 


m1.entrySet().removeAll(m2.entrySet());


where m1 is the Map to be modified and m2 is the display with the display to be removed from m1.

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private static <K, V> void fun(Map<K, V> a, Map<K, V> b) {
    Map<K, V> shortestMap = a.size() < b.size() ? a : b;
    Map<K, V> longestMap = a.size() > b.size() ? a : b;

    Set<Entry<K, V>> shortestMapEntries = shortestMap.entrySet();
    Set<Entry<K, V>> longestMapEntries = longestMap.entrySet();

    longestMapEntries.removeAll(shortestMapEntries);
}


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See java.util.Collection

boolean removeAll(Collection<?> c)
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private static <K, V> removeDuplicates(Map<K, V> map1, Map<K, V> map2) {
    for (K key : map1.keySet()) {
        V val1 = map1.get(key);
        V val2 = map2.get(key);
        if (val2 != null && val2.equals(val1)
            map2.remove(key);
    }
}
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