ArrayList in Java

February 14, 2023

What is an ArrayList?

Arraylists is a part of collection framework in java and is a kind of a resizable array which can be found in the java.util Package.
It implements the List interface of the collections framework.

Here, in the page we will discuss more about the ArrayList that are used in java.

ArrayLists in Java:

In Java, You can store the elements in a dynamic array using the Java ArrayList class of collection Framework. It is Similar to an array, but arraylist has no size restrictions. we can add or remove elements of an arraylist anytime. As a result, it is significantly more adaptable than a conventional array but it may be slower than standard arrays.

Syntax:

ArrayList<> Prep = new ArrayList<>(); // Initialiazation of an ArrayList.

Keywords and Variables

Basic Inbuilt Operations Of ArrayList:

There are several Operations of ArrayList that are available in java collection framework. Some of the important Operations are listed below:

Add Function:

The add() function is used to add an element to the arraylist in java.

Example:

Run

import java.util.*;

public class Main{
    public static void main(String[] args) {
        ArrayList arr = new ArrayList<>(); 

        // Adding elements to the Arraylist
        arr.add(1);
        arr.add(2);
        System.out.println(arr);
    }
}

Output:

[1, 2]

Explanation In the above example, We are initializing an Arraylist and We are adding two integer elements to the arraylist using the add function of Integer class.

Delete Function:

The Delete() function in java is used to delete an element of an arraylist in java. We can delete an element with the help of its index.

Example:

Run

import java.util.*;

public class Main{
    public static void main(String[] args) {
        ArrayList arr = new ArrayList<>();

        // Adding elements to the arraylist 
        arr.add(1);
        arr.add(2);
        arr.add(3);
        System.out.println("Before Deleting :" + arr);

        // removing an element using the remove function
        arr.remove(1);
        System.out.println("After Deleting :" + arr);
    }
}

Output:

Before Deleting :[1, 2, 3]
After Deleting :[1, 3]

Explanation In the above example, We are initializing an Arraylist and We have added three integer elements to the arraylist using the add function and we are deleting an element of the arraylist using the remove function of arraylist.

Set Function:

The set() function in java is used to change an element of an arraylist in java. We can change an element by the index of that arraylist.

Example:

Run

import java.util.*;

public class Main{
    public static void main(String[] args) {
        ArrayList arr = new ArrayList<>(); 

        // Adding elements to the arraylist
        arr.add(1);
        arr.add(2);
        arr.add(3);
        System.out.println("Before Changing :" + arr);

        // changing a specific element of arraylist
        arr.set(1, 5);
        System.out.println("After Changing :" + arr);
    }
}

Output:

Before Changing :[1, 2, 3]
After Changing :[1, 5, 3]

Explanation In the above example, We are initializing an Arraylist and We have added three integer elements to the arraylist using the add function and we are changing a specific element of the arraylist using the set function of arraylist class.

Size Function:

The size() function in java is used to check the size or the length of the arraylist.

Example:

Run

import java.util.*;

public class Main{
    public static void main(String[] args) {
        ArrayList arr = new ArrayList<>();

        // Adding elements to the arraylist 
        arr.add(1);
        arr.add(2);
        arr.add(3);
        
        // Printing the size of the arraylist using size function
        System.out.println("Size of the ArrayList is : " + arr.size()); // size() function 
        of arraylist
    }
}

Output:

Size of the ArrayList is : 3

Sort Function:

The sort() function in java is used to sort the elements of the arraylist.

Example:

Run

import java.util.*;

public class Main{
    public static void main(String[] args) {
        ArrayList arr = new ArrayList<>(); 

        // Adding elements to the arraylist
        arr.add(2);
        arr.add(4);
        arr.add(1);
        System.out.println("Before Sorting : " + arr);
        
        // sorting the array of arraylist 
        Collections.sort(arr);
        System.out.println("After Sorting : " + arr);
    }
}

Output:

Before Sorting : [2, 4, 1]
After Sorting : [1, 2, 4]

Explanation In the above example, We are initializing an Arraylist and We have added three integer elements to the arraylist using the add function and we are sorting the arraylist using the sort function of collection class.

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ArrayList in Java

What is an ArrayList?

ArrayLists in Java:

Syntax:

Basic Inbuilt Operations Of ArrayList:

Add Function:

Example:

Delete Function:

Example:

Set Function:

Example:

Size Function:

Example:

Sort Function:

Example:

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