I have two Lists, List A and List B having different sizes. List A is getting parsed from file and List B is fetching data from the database.
class A{
private String id;
private String mobile;
}
class B{
private String id;
private String name;
private String address;
private String mobile;
private String pincode;
}
Now I want to Compare both the list and want to remove the respective ids from List A which are having the same mobile number as ListB .
Tried below code
private List<A> compareList(List<A> listA, List<B> listB){
List<A> temp = new ArrayList<>();
for(A a : listA){
for(B b : listB){
if(a.getId().equals(b.getId()) && !a.getMobile().equals(b.getMobile())){
temp.add(a);
}
}
}
return temp;
}
Can someone please guide me?
Your method creates a new list, instead of removing items from the existing list. Assuming you actually want to remove items, this is one way you can do it with the Java 8 streams API: remove an item from listA if it has the same mobile
as an item in listB:
listA.removeIf(a -> listB.stream()
.anyMatch(b -> Objects.equals(a.getMobile(), b.getMobile())));
The streams API in this case is a little difficult to read. Here's the same without using a stream:
for (B b : listB) {
listA.removeIf(a -> Objects.equals(a.mobile, b.mobile));
}
You can use a flag for existence and add in temp if not exists then temp contains only those elements of A which do not exist in B
List<A> temp = new ArrayList<>();
for(A a : listA){
boolean isExist = false;
for(B b : listB){
if(a.getId().equals(b.getId()) && a.getMobile().equals(b.getMobile())){
isExist = true; // if exist in List of B
break;
}
}
if(!isExist){ // if not exist in B then add in list
temp.add(a);
}
}
Note: In question you say to compare only mobile number but in code you are comparing id also, remove id equal check if you don't want it
I have two Lists, List A and List B having different sizes. List A is getting parsed from file and List B is fetching data from the database.
class A{
private String id;
private String mobile;
}
class B{
private String id;
private String name;
private String address;
private String mobile;
private String pincode;
}
Now I want to Compare both the list and want to remove the respective ids from List A which are having the same mobile number as ListB .
Tried below code
private List<A> compareList(List<A> listA, List<B> listB){
List<A> temp = new ArrayList<>();
for(A a : listA){
for(B b : listB){
if(a.getId().equals(b.getId()) && !a.getMobile().equals(b.getMobile())){
temp.add(a);
}
}
}
return temp;
}
Can someone please guide me?
I think you should keep the mobiles separately, as they can probably be repeated. And after that compare the main collection with this list of mobiles.
private static List<A> compareList(List<A> listA, List<B> listB) {
List<String> mobiles = listB.stream()
.map(B::getMobile)
.distinct()
.collect(Collectors.toList());
return listA.stream()
.filter(entity -> !mobiles.contains(entity.getMobile()))
.collect(Collectors.toList());
}
To create new filtered List
Collect all element in new list if condition does not match
List<A> filteredList =
aList.stream()
.filter(Predicate.not(a -> bList.stream().anyMatch(b -> a.getId().equals(b.getId()) && a.getMobile().equals(b.getMobile()))))
.collect(Collectors.toList());
For in place replacement
aList.removeIf(a -> bList.stream().anyMatch(b -> a.getId().equals(b.getId()) && a.getMobile().equals(b.getMobile())));
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