BetterLists (by Klemek)

An extension of the java.util.List interface which include some of the C# LINQ useful functions.

List classes are extended as well. (ArrayList -> BetterArrayList)

Current version v1.4

Before BetterLists :

ArrayList<Contact> contacts = someFunction();

ArrayList<String> contactsEmails = new ArrayList<>();
for(int i = 5; i < contacts.size(); i++){
	if(c.getEmail() != null){
		contactsEmails.add(c.getEmail());
	}
}

With BetterLists :

BetterArrayList<Contact> contacts = BetterArrayList.fromList(someFunction());

BetterList<String> contactsEmails = contacts.skip(5)
					.where(c -> c.getEmail() != null)
					.<String>select(c -> c.getEmail());

NOTE : Please note that, unlike C# LINQ, these functions are not optimized at low levels and will have the same impact as standard loops in your program.

Maven

You can use this project as a maven dependency with this :

<repositories>
    ...
    <repository>
        <id>fr.klemek</id>
        <url>https://github.com/klemek/mvn-repo/raw/master</url>
    </repository>
</repositories>
...
<dependencies>
    ...
    <dependency>
        <groupId>fr.klemek</groupId>
        <artifactId>betterlists</artifactId>
        <version>1.4</version>
    </dependency>
</dependencies>

All code examples

List

Name	Description
all	Determines whether all elements of the sequence satisfy a condition.
any	Determines whether any element of the sequence satisfies a condition.
count	Returns a number that represents how many elements in the specified sequence satisfy a condition.
exclusion	Produces the set exclusion of two sequences.
first / firstOrDefault	Returns the first element in the sequence that satisfies a specified condition. (Returns an error if no elements match the condition unless you use the firstOrDefault function)
last / lastOrDefault	Returns the last element in the sequence that satisfies a specified condition. (Returns an error if no elements match the condition unless you use the lastOrDefault function)
max	Invokes a transform function on each element of the sequence and returns the maximum nullable Double value.
mean	Computes the mean of the sequence of Double values that are obtained by invoking a transform function on each element of the input sequence.
min	Invokes a transform function on each element of the sequence and returns the minimum nullable Double value.
orderBy / orderByDescending	Sorts the elements of a sequence in ascending order by using a specified comparator. (You can user orderByDescending to change the order)
reverse	Inverts the order of the elements in the sequence.
select	Projects each element of a sequence into a new form.
selectMany / selectManyArrays	Projects each element of a sequence into a new list and flattens the resulting sequences into one sequence.
skip / skipWhile	Bypasses elements in the sequence as long as a specified condition is true and then returns the remaining elements.
sum	Computes the sum of the sequence of Double values that are obtained by invoking a transform function on each element of the input sequence.
take / takeWhile	Returns a specified number of contiguous elements from the start of the sequence.
union	Produces the set union of two sequences.
where	Filters a sequence of values based on a predicate.

all

Determines whether all elements of the sequence satisfy a condition.

BetterArrayList<Contact> contacts = BetterArrayList.fromList(someFunction());

boolean allAdults = contacts.all(c -> c.getAge() >= 21);

any

Determines whether any element of the sequence satisfies a condition.

BetterArrayList<Contact> contacts = BetterArrayList.fromList(someFunction());

boolean someUnderage = contacts.any(c -> c.getAge() < 21);

count

Returns a number that represents how many elements in the specified sequence satisfy a condition.

BetterArrayList<Contact> contacts = BetterArrayList.fromList(someFunction());

int adultsCount = contacts.count(c -> c.getAge() >= 21);

exclusion

Produces the set exclusion of two sequences.

BetterArrayList<Contact> frenchContacts = BetterArrayList.fromList(someFunction());
ArrayList<Contact> validContacts = someOtherFunction();

BetterList<Contact> invalidFrenchContacts = frenchContacts.exclusion(validContacts);

first / firstOrDefault

Returns the first element in the sequence that satisfies a specified condition. (Throws an error if no elements match the condition unless you use the firstOrDefault function)

BetterArrayList<Contact> contacts = BetterArrayList.fromList(someFunction());

Contact firstManager = contacts.first(c -> c.isManager()); //can throw NoSuchElementException
Contact firstContact = contacts.firstOrDefault(null); //return null if the list is empty

last / lastOrDefault

Returns the last element in the sequence that satisfies a specified condition. (Throws an error if no elements match the condition unless you use the lastOrDefault function)

BetterArrayList<Contact> contacts = BetterArrayList.fromList(someFunction());

Contact lastRegular = contacts.last(c -> !c.isManager()); //can throw NoSuchElementException
Contact lastManager = contacts.lastOrDefault(c -> c.isManager(), null); //return null there is no manager

max

Invokes a transform function on each element of the sequence and returns the maximum nullable Double value.

BetterArrayList<Contact> contacts = BetterArrayList.fromList(someFunction());

int maxAge = (int)contacts.max(c -> (double)c.getAge());

mean

Computes the mean of the sequence of Double values that are obtained by invoking a transform function on each element of the input sequence.

BetterArrayList<Contact> contacts = BetterArrayList.fromList(someFunction());

int meanAge = (int)contacts.mean(c -> (double)c.getAge());

min

Invokes a transform function on each element of the sequence and returns the minimum nullable Double value.

BetterArrayList<Contact> contacts = BetterArrayList.fromList(someFunction());

int minAge = (int)contacts.min(c -> (double)c.getAge());

orderBy / orderByDescending

Sorts the elements of a sequence in ascending order by using a specified comparer. (You can user orderByDescending to change the order)

BetterArrayList<Contact> contacts = BetterArrayList.fromList(someFunction());

BetterList<Contact> orderedContacts = contacts.orderBy(c -> c.getName);
BetterList<Contact> orderedContacts2 = contacts.orderByDescending(c -> c.getAge()); //oldest first

reverse

Inverts the order of the elements in the sequence.

BetterArrayList<Contact> contacts = BetterArrayList.fromList(someFunction());

BetterList<Contact> reversedContacts = contacts.reverse();

select

Projects each element of a sequence into a new form.

BetterArrayList<Contact> contacts = BetterArrayList.fromList(someFunction());

BetterList<String> contactsMails = contacts.select(c -> c.getEmail());

selectMany / selectManyArrays

Projects each element of a sequence into a new list and flattens the resulting sequences into one sequence.

BetterArrayList<Contact> contacts = BetterArrayList.fromList(someFunction());

BetterList<String> contactsNumbers = contacts.selectMany(c -> c.getAllPhoneNumbers());
BetterList<String> contactsMails = contacts.selectManyArrays(c -> c.getEmail().split(";"));

skip / skipWhile

Bypasses elements in the sequence as long as a specified condition is true and then returns the remaining elements.

BetterArrayList<Contact> contacts = BetterArrayList.fromList(someFunction());

BetterList<Contact> contacts2 = contacts.skip(3);
BetterList<Contact> contacts3 = contacts.skipWhile(c -> c.getEmail().startsWith("society"));

sum

Computes the sum of the sequence of Double values that are obtained by invoking a transform function on each element of the input sequence.

BetterArrayList<Contact> contacts = BetterArrayList.fromList(someFunction());

double salary = contacts.skip(c -> c.getSalary());

take / takeWhile

Returns a specified number of contiguous elements from the start of the sequence.

BetterArrayList<Contact> contacts = BetterArrayList.fromList(someFunction());

BetterList<Contact> contacts2 = contacts.take(5);
BetterList<Contact> contacts3 = contacts.takeWhile(c -> c.getEmail().startsWith("society"));

union

Produces the set union of two sequences.

BetterArrayList<Contact> frenchContacts = BetterArrayList.fromList(someFunction());
ArrayList<Contact> validContacts = someOtherFunction();

BetterList<Contact> validFrenchContacts = frenchContacts.union(validContacts);

where

Filters a sequence of values based on a predicate.

BetterArrayList<Contact> contacts = BetterArrayList.fromList(someFunction());

BetterList<Contact> validContacts = contacts.where(c -> c.getEmail() != null);