kiri :
All,
I have a object
public class Device {
public String getUserId() {
return userId;
}
public String getDeviceId() {
return deviceId;
}
}
I get all the List of Values
List<Device> uList = getList();
In the List i have a duplicate values Based on userId Now i want to get Unique list which will remove the duplicates of userId
How can i acheive it, I am very much new to Java
shmosel :
The simplest way is to create a Map where the key is the userId:
Map<String, Device> map = new HashMap<>();
devices.forEach(d -> map.put(d.getUserId(), d));
List<Device> uniques = new ArrayList<>(map.values());
Or, using streams:
Map<String, Device> map = devices.stream()
.collect(Collectors.toMap(Device::getUserId, d -> d, (a, b) -> a));
List<Device> uniques = new ArrayList<>(map.values());
Alternatively, you can dump them in a TreeSet with a comparator that checks userId:
Set<Device> set = new TreeSet<>(Comparator.comparing(Device::getUserId));
set.addAll(devices);
List<Device> uniques = new ArrayList<>(set);
All of this assumes you're not concerned about discrepancies in deviceId. Otherwise, take a look at Map.merge() or the corresponding Collectors.toMap() overload.
Guess you like
Origin http://43.154.161.224:23101/article/api/json?id=309282&siteId=1