List<Map<String, Object>> to Map<String, String[]> - list

Question

I have a List of Map List<Map<String, Object>>. I want to move to Map<String, String[]>
Can someone please let me know how to convert?
List<Map<String, Object>> currentList = new ArrayList<Map<String, Object>>();
Map<String, Object> currMap = new HashMap<String, Object>();
currMap.put("A", "ABC");
currMap.put("B", "PQR");
currMap.put("C", "XYZ");
currentList.add(currMap);
currMap.put("A", "123");
currMap.put("B", "456");
currMap.put("C", "789");
currentList.add(currMap);
currMap.put("A", "OOO");
currMap.put("B", "ZZZ");
currentList.add(currMap);
To-be :
"A", ["ABC", "123", "OOO"],
"B", ["PQR", "456", "ZZZ"],
"C", ["XYZ", "789", ""]

Answer 1

One way using streams would be:
currentList.stream()
.flatMap(map -> map.entrySet().stream())
.collect(Collectors.groupingBy(Entry::getKey, Collectors.mapping(Entry::getValue, Collectors.toList())));
This would result in:
{A=[ABC, 123, OOO], B=[PQR, 456, ZZZ], C=[XYZ, 789]}
As a sidenote, the way you are generating currentList in the example does not result in a list of maps as you are probably expecting. As it is, you will end up with 3 references to the same map in the list.