Java Tutorial

Java Tutorial Java Features C++ vs Java Java History Java Hello World Java Development Kit Java Runtime Environment Java Virtual Machine Difference between JDK, JRE, and JVM Memory Areas in Java Java Operators Java Keywords Primitive Data Types Variables

Java Loops

Java Do While Loop Java While Loop Java For Loop Java Enhanced For Loop

Java Programs

Java Basic Programs Factorial Program in Java Fibonacci Series Program in Java Prime Number Program in Java Palindrome Number Program in Java Armstrong Number Program in Java Anagram Program in Java Pattern Programs in Java Calculator Program in Java Leap Year Program in Java Addition Program in Java Number Pattern Programs in Java Star Pattern Programs in Java Package Program in Java Pyramid Program in Java Sorting Program in Java String Palindrome Program in Java Even Odd Program in Java For Loop Program in Java If Else Program in Java Switch Case Program in Java GCD Program in Java LCM Program in Java Hello Program in Java Matrix Program in Java Menu Driven Program in Java Series Program in Java Client Server Program in Java Swapping Program in Java Pig Latin Program in Java Tower of Hanoi Program in Java Recursion Program in Java Matrix Multiplication Program in Java Perfect Number Program in Java Classes and Objects in Java Example Programs String Programs in Java Array Programs in Java Constructor Program in Java Inheritance Program in Java Abstract class Program in Java Interface Program in Java Encapsulation Program in Java Polymorphism Program in Java Exception Handling Program in Java Multithreading Program in Java Thread Program in Java Collection Programs in Java ArrayList Program in Java Stack Program in Java Applet Program in Java Swing Program in Java JDBC Program in Java How to run Java program in command prompt How to run Java program in Eclipse Program to find and replace characters on string in java Program to find the duplicate characters in a string Program to check whether a given character is present in a string or not Java Program to Print Permutations of String Java program to find frequency of characters in a string Java Program to remove duplicate characters in a string

Java Sorting

Sorting Algorithms in Java Merge Sort in Java Quick Sort in Java Bubble Sort in Java Insertion Sort in Java Selection Sort in Java Heap Sort in Java Radix Sort in Java Topological Sort in Java Bucket Sort in Java Counting Sort in Java

Java OOPs Concepts

OOPs - Object Oriented Programming Objects and Classes in Java Methods in Java Java Naming Conventions Constructors in Java Java this keyword Java static keyword Inheritance in Java Aggregation in Java Java super keyword Constructor Chaining and Constructor Overloading Java Polymorphism Static and Dynamic Binding in Java Java Abstraction Abstract class in Java Interface in Java Difference between Abstract class and Interface Java final keyword Packages in Java Access Modifiers in Java Java Wrapper classes Java Numbers Java Characters Java Integer Java Boolean Java Arrays Java Command Line Arguments Java strictfp Keyword Java Math

Java Strings

Java Strings Java String Methods StringBuilder in Java StringBuffer in Java Java Regular Expressions StringBuffer vs StringBuilder String vs StringBuffer String vs StringBuilder String Manipulation in Java Java String Concatenation How to Reverse a String in Java String Array in Java How to Compare Two Strings in Java How to Concatenate Two Strings in Java Why String in Immutable in Java Java.lang.NumberFormatException for Input String String Pool in Java Java Generate Random String How to take String Input in Java Java String Interview Questions

Java Exceptions

Exception Handling in Java Java try catch Java throw Java throws Difference between throw and throws Java finally Java Custom Exception Java Exception Propagation

Garbage Collection

Automatic Resource Management in Java Java Garbage Collection Java finalize() Java gc() Difference between final, finally and finalize


Multithreading in Java Process and Thread in Java Basic Terms in Multithreading Java Thread creation Thread Scheduler in Java Java Thread class DeadLock in Java

Java IO

Java IO Java Read File Java file Reader Java Buffer Reader Java file Writer Java BufferedWriter Java InputStreamReader Scanner in Java Java StringReader Java StringReader Class Java PrintWriter Java File Java Read File Line By Line Java FileInputStream Java FileOutputStream Java Create File Java Delete File Java Open File Java Read File to String Java copy file Java Read JSON file Jar File in Java Java FileNotFoundException


Java Serialization Java transient


Java Network Programming Java Socket Programming Java URL Java URLConnection HttpURLConnection in Java Java InetAddress Java DatagramSocket and Java DatagramPacket


Java AWT


Swing in Java

Java Collections

Collections in Java Java List Interface ArrayList in Java LinkedList in Java Vector in Java Stack in Java ArrayList vs LinkedList in Java ArrayList vs Vector in Java Java Set Interface HashSet in Java LinkedHashSet in Java TreeSet in Java Java Queue Interface PriorityQueue in Java ArrayDeque in Java Java Map Interface HashMap in Java LinkedHashMap in Java TreeMap in Java Dictionary in Java Hashtable in Java Properties in Java Collections class in Java Java Comparable Java Comparator Comparable vs Comparator in Java

Java Generics

Generics in Java

Java Annotations

Annotations in Java


Java JDBC Tutorial JDBC Architecture Types of JDBC Drivers JDBC vs ODBC Java Database Connectivity with MySQL Statements in java Prepared statement in Java Resultset in java Java ResultSetMetaData DatabaseMetaData in Java Callable Statement in Java Transaction Management in java

Java Differences

Java vs JavaScript Python vs Java Kotlin vs Java Java vs C++ C# vs Java Static vs Non-static in Java C vs Java int vs Integer in Java Stack vs Heap in Java Java Array vs ArrayList

How to

How to run Java program How to set path in Java How to check the Java version in cmd How to install Java in Windows 10 How to run Java program in cmd How to add double quotes in a string in Java How to convert list to String in Java How to call a method in Java How to sort an array in Java How to iterate HashMap in Java How to write Java program How to create an array in Java How to create a package in Java How to generate random numbers in Java How to input String in Java How to create thread in Java How to find length of String in Java How to sort a string in Java How to use scanner in Java How to achieve multiple inheritance in Java How to find the length of an Array in Java How to run Java program in Eclipse How to call a function in Java How to create array of objects in Java How to create custom exception in Java How to import packages in Java How to run applet Program in Java How to take Array Input in Java How to achieve abstraction in Java How to call static method in Java How to compare characters in Java How to initialize string array in Java How to Install Java on MAC How to run java program in ubuntu How to find characters with the maximum number of times in a string java How to Set Java_home in Linux How to Split the String in Java with Delimiter How to Split String by Comma in Java How to remove special characters from String in Java How to remove last character from String in Java

Java 8 Features

Java 8 Features Lambda Expressions in Java Functional Interface in Java Streams in Java Java Base64 Encoding and Decoding Parallel Arrays Sort in Java

Java 9 Features

Java 9 Tutorial Java 9 Try With Resources Java 9 Interface Private Method

Java Servlet Tutorial

Java Servlets Tutorial

Java JSP Tutorial

Java JSP Tutorial

Hibernate Tutorial

Hibernate Tutorial

Spring Tutorial

Spring Tutorial

Spring MVC Tutorial

Spring MVC Tutorial

Jenkins Tutorial

Jenkins Tutorial

Java Math Methods

Math.abs() Math.acos() Math.addExact() Math.asin() Math.atan () Math.atan2() Math.cbrt() Math.ceil() Math.copysign() Math.cos() Math.cosh() Math.decrementExact() Math.exp() Math.expm1() Math.floor() Math.floorDiv() Math.floorMod() Math.getExponent() Math.hypot() Math.IEEEremainder() Math.incrementExact() Math.log() Math.log10() Math.log1p() Math.max() Math.min() Math.multiplyExact() Math.multiplyFull() Math.negateExact() Math.nextAfter() Math.nextDown() Math.nextUp() Math.pow() Math.random() Math.rint() Math.round() Math.scalb() Math.signum() Math.sin() Math.sinh() Math.sqrt() Math.subtractExact() Math.tan() Math.tanh() Math.toDegrees() Math.toIntExact() Math.toRadians() Math.ulp()

Java String Methods

toCharArray() copyValueOf() endsWith() equals() equalsIgnoreCase() format() getBytes() getChars() hashCode() indexOf() intern() isEmpty() join() lastIndexOf() length() replace() replaceAll() replaceFirst() split() startsWith() subSequence() substring() toLowerCase() toUpperCase() trim() valueOf()

Java Conversion

Java Convert String to int Java Convert int to String Java Convert String to long Java Convert long to String Java Convert String to float Java Convert float to String Java Convert String to double Java Convert double to String Java Convert String to Date Java Convert Date to String Java Convert String to Object Java Convert Object to String Java Convert String to char Java Convert char to String Java Convert int to long Java Convert long to int


Functional Interfaces in Java Singleton class in Java Awesome explanation of Strings in Java Object class in Java Static class in Java All the important string methods in Java String Handling Method in Java What are Array strings in Java Advantages and Disadvantages of Strings in Java Big Decimal class in Java Class definition in Java Char and String differences in Java Difference between String, StringBuffer and StringBuilder in java Replace character in string Java String Coding Interview Questions in Java What is String in Java? String isnullorempty in Java String Matches in Java Trim Method in String Java Bean class in Java Libraries in Java Arithmetic Operations on String in Java Convert Char array to string in java Check whether Java is installed or not How to calculate time difference in Java How to stop execution after a certain time in Java Jagged Array in Java Java ArraylistRemove() Time Complexity Java Swing Time Picker Zigzag Array in Java Array and String based questions in Java Array and String with Examples in Java Best Practices to use String Class in Java What is string in Java why it's immutable Java String Java String Inbuilt functions Java String Matches vs Contains Sum of digits in string in java Check the presence of Substring in a String in java Java import packages Interfaces and Classes in Strings in Java Maximum length of string in java Hidden classes in Java Class memory in Java public static void main string args meaning in java Reverse a String in Java String Concatenation in Java Difference between String and Char Array in Java Buffer reader to read string in Java

Java ArraylistRemove() Time Complexity

In this tutorial, we will learn about how we can remove time complexity in Java ArrayList. But unless we will not learn what is ArrayList, we don’t understand this process. So, first of all, we learn about what is ArrayList in java then we learn about time complexity and finally we will learn how we can remove time complexity in java ArrayList.

What is an ArrayList in Java?

The ArrayList classis part of java.util package is a dynamic array. ArrayLists can modify their size dynamically, butbuilt-in arrays are fixed in size. An ArrayList can have elements added and removed as needed, assisting the user with memory management.

In C++, ArrayLists are equivalent to vectors:

How to Create an ArrayList

The syntax for declaring an ArrayList is as follows. An ArrayList, like arrays, requires the user to declare the data type of its components, and its initial size is determined by the user.

import java.util.ArrayList; //the ArrayList class to be imported
class My_Class
    public static void main(String args[] ) 
ArrayList<String> shapes = new ArrayList<String>();
    // Make an ArrayList object with the data type of string

ArrayList Methods

The ArrayList class has a number of useful functions, which are listed below:

  • Add a new item: To add an item to the beginning of an ArrayList, use the add() function. This item's index is 0 and all other indices have been incremented by1.
  • To go to an item: In the ArrayList,the get() function is used to access an element using an index as input.
  • Set an item: In the ArrayListsets an element at the specified index using the set() function, which takes an index as input.
shapes.set(2, "triangle")
  • Remove an item: An element in an ArrayList is removed using the remove() method, which takes an index as input. All elements in front of the eliminated element have their indexes decreased by one.
  • Remove all items: To delete all elements from an ArrayList, use the clear() function.
  • Size of ArrayList: The number of elements in an ArrayList can be found using the size() function.

Implementation of ArrayList

The implementation of an ArrayList in Java code is shown below.

import java.util.ArrayList; // the ArrayList Class to be imported
class My_Class {
  public static void main(String args[] ) {
ArrayList shapes = new ArrayList(); //Make an ArrayList with the new data type of string

shapes.add("pentagon");// at index 0, add pentagon
shapes.add("hexagon ");     // at index 1, add hexagon
shapes.add("square");    // at index 2, add square
shapes.add("rhombus");    // at index 3, add rhombus
shapes.add("triangle ");     // at index 4, add triangle
shapes.add("rectangle");   // at index 5, add rectangle
shapes.add("octagon ");   // at index 6, add octagon

System.out.println(shapes); // every ArrayList shape's element to be printed.

System.out.println(shapes.get(4)); // at index 4, print element

shapes.remove(2);          // at index 2, remove element
shapes.remove(5);          // at index 5, remove element

System.out.println(shapes); //every element of ArrayList shapes to be printed

shapes.set(4,"circle"); // with circle at index 4, replaces element

System.out.println(shapes); // every element of ArrayList shapes to be printed

System.out.println(shapes.size()); // in the ArrayList
theelements number to be printed

shapes.clear();             //  every elements in the ArrayList is remove
System.out.println(shapes); // every element of ArrayList shapes to be printed



[pentagon,hexagon, square, rhombus, triangle, rectangle, octagon]
[pentagon, square, rhombus, triangle, rectangle]
[pentagon, square, rhombus, triangle, circle]


In Java, the ArrayList is backed by an array. This aids in comprehending the implementation's internal logic. This page contains a more detailedexplanation of the ArrayList.

So, let's start with a high-level look at the temporal complexity of typical operations:

  • add() takes O(1) time: although, in the worst-case situation, when a new array is built and all the elements are copied to it, it takes O(2) time (n)
  • add(index, element): takes O(n) time on average.
  • get(): returns a value that is always the same, the operation O(1)
  • remove(): takes O(n) time to execute. To discover the element that qualifies for removal, we must loop through the entire array.
  • indexOf():  also a linear time function. It iterates across the internal array, checking each entry one by one, hence this operation's temporal complexity is always O(n).
  • contains(): because it's based on indexOf(), it'll take O(n) time to execute.

Time Complexity

The term "time complexity" refers to how long a block of code or an algorithm takes to process or runin relation to the size and cost of the input in programming.

It won't take an algorithm's entire execution time into consideration. Instead, it will give details on how the amounts of operations in an algorithm change the execution time (increase or decrease).

Yes, as the word implies, the time required is purely dictated by the number of iterations of one-line statements within the code.

Take a look at the code below.

using namespace std;
int main()
cout<<” Hello Dev_1\n” ;
cout<<” Hello Dev_2\n” ;
cout<<” Hello Dev_3\n” ;

Despite the fact that the main() method contains three different statements, the overall time complexity is still O(1) because each statement takes a unit of time to complete.

Consider the following instance:

using namespace std;
int main()
int j, no=35;
for(j =1 ; j<= no , j++)
cout<<” Hello Dev_1\n” ;
cout<<” Hello Dev_2\n” ;
cout<<” Hello Dev_3\n” ;

The O(1) piece of code (the three cout instructions) is encapsulated behind a looping statement that iterates for 'n' times. As a result, our entire time complexity is n*O(1), or O(1) (n).

You may assert that the time required is constant when an algorithm employs statements that are only executed once. However, when the statement is in a loop condition, the amount of time required increases in direct proportion to how many times the loop is set up to run.

The amount of time needed increases according to the number of times each statement is run when an algorithm contains both LOOP statements and single-executed statements, or nested LOOP statements.

Finding and recognizing the source of a recursive function's temporal complexity, for instance, can help reduce processing time from 600ms to 100ms when the function is run multiple times.That is what temporal complexity analysis is attempting to accomplish.

Notations for Time Complexity

Some of the most frequent asymptotic notations for estimating the running time complexity of an algorithm are listed below:

  • O Notation
  • Ω Notation
  • θ Notation
  1. Big Oh Notation, Ο
    The Big-O notation O is a systematic technique to express the upper limit of an algorithm's running time (n). It determines the worst-case time complexity or the amount of time it will take an algorithm to finish its execution.

    Also, unless otherwise stated, this is the most generally used notation for describing the temporal complexity of distinct algorithms.

    Definition: Allow g and f to be methods from the natural numbers set (N). If there is a constant c > 0 and a natural number n0, the function f is said to be O(g).

    For any n >= n0, f (n) = cg(n).
  2. Omega Notation, Ω
    The notation is a systematic technique to express the lowest bound of an algorithm's running time (n). It determines the best-case time complexity, or how long it will take an algorithm to finish in the minimum amount of time.

    Definition: There are positive constants c and n0 such that 0 cg(n) f(n) for all n n0 (g(n)) = f(n).

    The following equation can be characterized as a function f(n) belonging to the set (g(n)) if and only if a positive constant c (c > 0) exists such that it is larger than c*g(n) for an adequately high value of n.

    Ω(g(n)) is the minimal time required for the execution of an algorithm to be complete.
  3. Theta Notation, θ
    The notation is a systematic technique to express both the lower and upper bounds of an algorithm's running time (n).

    Definition: θ(g(n)) = {f(n): there exist certain positive constants x1, x2 and n0 such that 0 ≤ x1g(n) ≤ f(n) ≤ x2g(n) for all n ≥ n0}

Remove Time Complexity by Index: O(N)

Because ArrayList implements the RandomAccess interface, reading anyrandom element takes only O(1) time. However, because the other parts must also be moved from one position to the left, the entire time complexity rises to O(N).

If the index is given as a parameter, the remove method will also delete and return the element that was removed. The delete method, on the other hand, throws IndexOutOfBoundsException if the index is not inside the ArrayList's range.

Java ArraylistRemove() Time Complexity

Remove Time Complexity by Value: O(N)

When we send an object to the remove method, it must loop through all of the list's elements until it identifies the one that needs to be removed. And, of course, the remaining pieces on the right must be shifted as well. As a result, the total temporal complexity is O(N).