Best answer: How do you add different data types in an ArrayList in Java?

You can make it like : List sections = new ArrayList (); (Recommended) Another possible solution would be to make a custom model class with two parameters one Integer and other String. Then using an ArrayList of that object.

Can an ArrayList have different data types?

The ArrayList class implements a growable array of objects. ArrayList cannot hold primitive data types such as int, double, char, and long. With the introduction to wrapped class in java that was created to hold primitive data values.

How do ArrayList use different data types?

We can use the Object class to declare our ArrayList using the syntax mentioned below. ArrayList<Object> list = new ArrayList<Object>(); The above list can hold values of any type. The code given below presents an example of the ArrayList with the Objects of multiple types.

Can ArrayList have multiple types?

There is really one case where you can realistically add multiple types of objects to an ArrayList in Java. If you do not not specify a type for the ArrayList, or if you specify the type to be Object, any object (e.g. Dog or String like in your question) would be able to be added to the ArrayList.

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How do you add multiple data to an ArrayList?

Add Multiple Items to an Java ArrayList

  1. List<Integer> anotherList = Arrays. asList(5, 12, 9, 3, 15, 88); list. …
  2. List<Integer> list = new ArrayList<>(); Collections. addAll(list, 1, 2, 3, 4, 5);
  3. List<Integer> list = new ArrayList<>(); Integer[] otherList = new Integer[] {1, 2, 3, 4, 5}; Collections.

Can List have different data types?

There are no inherent problems in having multiple data types in a list. Problems may, of course, arise if you try to use that list for something that expects it to be all the same type. In your example, if this is all you’re doing with it, there’s no way for it to become a problem.

What data type is an ArrayList?

The ArrayList class implements a growable array of objects.

ArrayLists cannot hold primitive data types such as int, double, char, and long (they can hold String since String is an object, and wrapper class objects (Double, Integer). Like an array, it contains components that can be accessed using an integer index.

Which two Cannot be stored in an ArrayList?

The ArrayList class implements a growable array of objects. ArrayLists cannot hold primitive data types such as int, double, char, and long (they can hold String since String is an object, and wrapper class objects (Double, Integer).

What are the methods in ArrayList?

Methods of ArrayList

Method Description
void ensureCapacity(int requiredCapacity) It is used to enhance the capacity of an ArrayList instance.
E get(int index) It is used to fetch the element from the particular position of the list.
boolean isEmpty() It returns true if the list is empty, otherwise false.
Iterator()
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What is difference between array and ArrayList?

An array is basic functionality provided by Java. ArrayList is part of collection framework in Java. Therefore array members are accessed using [], while ArrayList has a set of methods to access elements and modify them. Array is a fixed size data structure while ArrayList is not.

Does ArrayList maintain insertion order?

Yes, ArrayList is an ordered collection and it maintains the insertion order. Yes. ArrayList is a sequential list. If you add elements during retrieval, the order will not remain the same.

What can an ArrayList hold?

The Java collection classes, including ArrayList, have one major constraint: they can only store pointers to objects, not primitives. So an ArrayList can store pointers to String objects or Color objects, but an ArrayList cannot store a collection of primitives like int or double.

What type of class is an ArrayList?

The ArrayList class extends AbstractList and implements the List interface. ArrayList supports dynamic arrays that can grow as needed. Standard Java arrays are of a fixed length.

How do you add multiple data to a list?

extend to extend the list by multiple values from any kind of iterable, being it another list or any other thing that provides a sequence of values. So you can use list. append() to append a single value, and list. extend() to append multiple values.

Can you add an ArrayList to an ArrayList?

Approach: ArrayLists can be joined in Java with the help of Collection. addAll() method. This method is called by the destination ArrayList and the other ArrayList is passed as the parameter to this method. This method appends the second ArrayList to the end of the first ArrayList.

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Can an ArrayList contain multiple references to the same object?

The ArrayList in java does not provide the checks for duplicate references to the same object. Therefore, we can insert the same object or reference to a single object as many times as we want.

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