Shan :
I have a List<Map<String, String>>. I would like to convert it into single map.
The list size can be 1..n. Not sure how to do that using Java 8 Stream?
List<Map<String, String>> mapList = new ArrayList<>();
Map<String, String> map1 = new HashMap<>();
map1.put("1", "One");
map1.put("2", "Two");
Map<String, String> map2 = new HashMap<>();
map2.put("3", "Three");
map2.put("4", "Four");
mapList.add(map1);
mapList.add(map2);
Map<String, String> finalMap = new HashMap<>();
We could do something like this in Java 7:
for(Map<String, String> map : mapList) {
for(String key : map.keySet()) {
finalMap.put(key, map.get(key));
}
}
System.out.println("Final Map " + finalMap); // Final Map {1=One, 2=Two, 3=Three, 4=Four}
Andronicus :
You can flatMap it and then use Collectors.toMap:
mapList.stream()
.flatMap(m -> m.entrySet().stream())
.collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));
Note, that duplicate keys are not handled. To ignore duplicates, you can use:
Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue, (v1, v2) -> v1)
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