What is Java hashmap?


The Java collections framework's HashMap class offers hash table data structure capability. The elements are kept in key/value pairs. Here, each value on a map is linked to a key, which acts as a distinctive identifier. The Map interface is implemented by the HashMap class. HashMap implementation in Java.


What is Hashmap? And why is it used for?

For mapping one arbitrary piece of data to another arbitrary piece of data, hashmaps are a highly helpful data structure. They rely on a strong modulus function, a set of "buckets," and a hash function. Maps are frequently used to connect two collections of data or to organize data using a common key.

Did you know?

Java's most well-known and frequently used full name is Just Another Virtual Accelerator

What are the advantages of Hashmap?

HashMap has the advantage that space complexity is O (n) O(n) O(n) and time complexity to insert and retrieve an item is typically O (1) O(1) O(1). Later on in the article, we'll examine how HashMap performs in Java.

How to implement a Java program?

  • Go to the directory where you saved the Java program (MyFirstJavaProgram.java) and open a command prompt window.
  • To compile your code, type "javac MyFirstJavaProgram.java" and hit Enter. The command prompt will advance you to the following line if your code is error-free (Assumption: The path variable is set).
  • To run your program, type 'java MyFirstJavaProgram' at this point.
  • The outcome will be visible and printed on the window.

Where Java is used?

 Web applications

In web applications such as e-commerce websites, social media networks, and enterprise-level systems, are frequently created using Java. For creating online applications, Java frameworks like Spring, Struts, and Hibernate are common alternatives.

 Mobile applications

Java is the preferred language for creating Android applications, which are accessed by billions of people worldwide. When creating cross-platform mobile applications with programs like Xamarin and PhoneGap, Java is also utilized.

 Enterprise application development

Large-scale corporate applications including those for banking, finance, healthcare, and supply chain management are frequently developed with the help of Java. Enterprise application development largely uses Java frameworks such as JavaServer Faces (JSF), Java Persistence API (JPA), and Java Message Service (JMS).

 Internet of Things (IoT)

Java is utilized widely in the development of IoT applications that require lightweight & scalable software solutions. For creating IoT applications, Java frameworks like Eclipse IoT, Kura, and ThingWorx are frequently used.

 Artificial intelligence & Machine learning

Java is utilized in the creation of applications for artificial intelligence (AI) and machine learning (ML). It is used particularly in the creation of tools for data processing and analysis. Java frameworks for building AI and ML applications, like Apache Spark, Deeplearning4j, and H2O.ai, are popular options.

 Game development

Java is used to create desktop and mobile games, and it serves as the core programming language for well-known game engines like LibGDX and jMonkeyEngine.

What are all the strengths of the Java platform?

The Java environment is well-liked for software development because of its many benefits, including,

 Platform independence

The Java platform's flexibility to run on several operating systems and hardware architectures without requiring any code adjustments is one of its main advantages. The Java Virtual Machine (JVM), which converts Java code into bytecode that can be executed on any system with a JVM installed, is used to do this.

 Object-oriented programing

Being an object-oriented programming language, Java was created with the idea of objects that include data and methods. Complex software systems are easier to create and manage as a result.


Java was made specifically to be a robust language that can gracefully manage mistakes and exceptions. It contains an internal memory management system, which lessens the possibility of crashes and memory leaks.

 Large & active community

One of the biggest and busiest communities in the software development industry is the Java community. This implies that there is a tonne of tools, frameworks, and libraries that may be utilized to hasten development and raise the caliber of the code.


With built-in tools for tracking issues like encryption, authentication, and access control, Java places a significant emphasis on security. Because of this, it is frequently used for creating applications for financial systems & healthcare systems that need a high level of security.


Because Java is a highly scalable language, it can easily manage huge and complicated software systems. It is frequently employed in the creation of enterprise-level applications, including supply chain management programs and e-commerce platforms.


Java has a strict backward compatibility policy. This quality makes sure that Java-based applications will function as expected for many years to come.

Can I do PhD in Java?

The list of qualifications for a PhD in Java programming includes things like exploring open EHR-based clinical recommendations for acute stroke care and research, approaches, and tools for automating end-to-end online testing, and the architecture of the Semantic Data Quality Management Framework (SDQM). Below are a number of PhD Java projects for your better understanding.

“Since everyone in the world is familiar with Java and eager to use it, the field of Java programming has always been booming.

It is hardly a brand-new development to highlight. Everyone has learned Java, whether it is as part of their education or just for fun. Because we are familiar with this field, it is simple to select a topic.

Additionally, it is platform-neutral. Java may be used to implement any application because it is compatible with all environments. Another popular high-level programming language is Java, which is utilized on a wide range of computing platforms, including business servers and embedded devices like mobile phones”