Given a map and the apex map method putAll()
map<String,Integer> intsByKey = new map<String,Integer> {'a' => 1, 'b' => 2}; intsByKey.putAll(new map<String,Integer> {'c' => 3, 'd' => 4, 'a' => 10});The documentation states that putAll replaces the contents of the target map
The new mappings from fromMap replace any mappings that the original
map had.So, how does one merge two maps in a convenient way?
Answer
Well, conveniently for us, the documentation is misleading/ambiguous and putAll does a true merge.
map<String,Integer> intsByKey = new map<String,Integer>
{'a' => 1, 'b' => 2};
intsByKey.putAll(new map<String,Integer>
{'c' => 3, 'd' => 4, 'a' => 10});
The value of intsByKey after the second statement is:
{a=10, b=2, c=3, d=4}
That is, putAll acts like addAll does for lists/sets
Props to Scott Hung’s blog for saving me the trouble of writing a for loop
Attribution
Source : Link , Question Author : cropredy , Answer Author : cropredy