Frequent question: How do you return an empty array list in java?

Can you return ArrayList in Java?

An ArrayList is a resizable class of java. util package. It is a scalable array, which means that the size of an array can be modified whenever you want.

How do you send an empty ArrayList in Java?

There are two ways to empty an ArrayList – By using ArrayList. clear() method or with the help of ArrayList. removeAll() method.

How do you return a null list in Java?

In Java, a null value can be assigned to an object reference of any type to indicate that it points to nothing. The compiler assigns null to any uninitialized static and instance members of reference type. In the absence of a constructor, the getArticles() and getName() methods will return a null reference.

What is an empty ArrayList in Java?

The isEmpty() method of ArrayList in java is used to check if a list is empty or not. It returns true if the list contains no elements otherwise it returns false if the list contains any element. Syntax: list_name.isEmpty() Parameter: It does not accepts any parameter.

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Can ArrayList be a return type?

4 Answers. If you cannot change the signature and it is mandatory to return an arraylist, then you can create an arraylist with just one element and return it. Something like this: ArrayList returnList = new ArrayList(); returnList.

How do you return an ArrayList?

add(3); return(numbers); } } public class T{ public static void main(String[] args){ Test t = new Test(); ArrayList<Integer> arr = t. myNumbers(); // You can catch the returned integer arraylist into an arraylist. } }

What does an empty ArrayList return?

emptyList() returns an immutable list, i.e., a list to which you cannot add elements if you want to perform any operation on your list, then create new instance of list and return it. … getResultList(); } else { return new ArrayList<Lookup>(); // return array list instance. }

How do you check if an ArrayList is empty?

To check if an ArrayList is empty, you can use ArrayList. isEmpty() method or first check if the ArrayList is null, and if not null, check its size using ArrayList. size() method. The size of an empty ArrayList is zero.

How do you create an empty ArrayList?

The general syntax of this method is:

ArrayList<data_type> list_name = new ArrayList<>(); For Example, you can create a generic ArrayList of type String using the following statement. ArrayList<String> arraylist = new ArrayList<>(); This will create an empty ArrayList named ‘arraylist’ of type String.

Should I return null or throw exception?

Only throw an exception if it is truly an error. If it is expected behavior for the object to not exist, return the null. Otherwise it is a matter of preference. As a general rule, if the method should always return an object, then go with the exception.

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Is it better to return null or empty list?

It is better to return empty collections rather than null when writing methods. The reason being that any code calling your method then doesn’t need to explicitly handle a special null case. Returning an empty collection makes the null check redundant and results in much cleaner method calling code.

Is an empty list null Java?

An empty collection isn’t the same as null . An empty collection is actually a collection, but there aren’t any elements in it yet. null means no collection exists at all.

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