How to declare ArrayList alongside values inwards Java? Examples

Sometimes you lot desire to practise an ArrayList amongst values, but similar you lot initialize t at the fourth dimension of declaration, every bit shown below:

int[] primes = {2, 3, 5, 7, 11, 13, 17};
or
String[] names = {"john", "Johnny", "Tom", "Harry"};

but unfortunately, ArrayList doesn't back upwardly such form of annunciation inward Java. But don't worry, at that topographic point is a workaround to declare an ArrayList amongst values e.g. String, integers, floats or doubles past times using Arrays.asList() method, which is goose egg but a shortcut to convert an Array to ArrayList.

Declaring ArrayList amongst values inward Java

Here is a code instance to exhibit you lot how to initialize ArrayList at the fourth dimension of declaration:

ArrayList<Integer> numbers = new ArrayList<>(Arrays.asList(1, 2, 3, 4, 5, 6));

This is how you lot declare an ArrayList of Integer values. You tin practise same to practise an ArrayList amongst String objects every bit well, e.g.

ArrayList<String> cities = new ArrayList<>(Arrays.asList("London", "Tokyo", "New York"));

Similarly hither is how you lot should practise ArrayList amongst float values:

ArrayList<Float> floats = new ArrayList<>(Arrays.asList(3.14f, 6.28f, 9.56f));

don't forget the suffix 'f', it's of import because past times default floating-point numbers are double inward Java.

Some programmer's too similar declare a List amongst values inward i line as:

List<Integer> listOfInts = Arrays.asList(1, 2, 3);

This is Ok to impress values, but it's non an ArrayList. You cannot add together or take elements into this listing but when you lot practise an ArrayList similar new ArrayList(Arrays.asList()), you lot acquire a regular ArrayList object, which allows you lot to add, take together with laid values.

Here is the prissy summary of code examples of how to brand an ArrayList of values inward Java:

but similar you lot initialize t at the fourth dimension of annunciation How to declare ArrayList amongst values inward Java? Examples

That's all nearly how to declare an ArrayList amongst values inward Java. You tin utilisation this technique to declare an ArrayList of integers, String or whatsoever other object. It's genuinely useful for testing together with demo purpose, but I convey too used this to practise an ArrayList of an initial laid of fixed values.

Further Learning
Java Fundamentals: Collections
From Collections to Streams inward Java 8 Using Lambda Expressions
Grokking Algorithms past times Aditya Bhargava
Java Programming Interview Exposed past times Makham

Related Java ArrayList Tutorials
If you lot similar this Java tip together with wants to larn to a greater extent than nearly how to operate amongst ArrayList inward Java, cheque out following Java tutorials together with articles:

What is the deviation betwixt an array together with an ArrayList inward Java? (answer)
The deviation betwixt CopyOnWriteArrayList together with synchronized ArrayList inward Java?(answer)
What is the deviation betwixt ArrayList together with Vector inward Java? (answer)
How to avoid ConcurrentModificationException spell looping over ArrayList? (solution)
A deviation betwixt LinkedList together with ArrayList inward Java? (answer)
How to take elements from ArrayList inward Java? (example)
What is the deviation betwixt HashSet together with ArrayList inward Java? (answer)
How to opposite an ArrayList inward Java? (solution)
What is the deviation betwixt ArrayList together with HashMap inward Java? (answer)
How to loop over ArrayList inward Java? (answer)
How to sort an ArrayList? (solution)
How to acquire the subList() from an ArrayList inward Java? (solution)
The difference betwixt length together with size of ArrayList? (answer)
How to sort the ArrayList inward decreasing order? (example)

Further Reading
If you lot a beginner inward Java together with but started learning, together with thus you lot tin read Head First Java sec Edition, but if you lot are experienced Java developer together with looking forwards to taking your noesis of Java Collections framework to side past times side marker together with thus read Java Generics together with Collections from Maurice Naftalin.