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What are the components of Java Program

What are the components of a Java Program?‘What are the components of Java Program?’

If you know the components of Java, you know almost everything in java to become an expert programmer. Knowledge of components makes your java learning curve faster and easy. If you go through the complete topic and apply the concepts explained, you will feel more comfortable & confident while writing the code. You will start visualizing the codes & implementations quickly. It will also help you to design a best quality application in java. Now let’s talk about ‘What are the components of Java Program?’

What are the components of Java Program?

If this term is new to you in Java, just think about terms part, element, section, piece, portion, segment, ingredient. All are synonyms of components. Till the time you must have got the idea what is the component. Now let’s guess what are the components of a Java Program?If there is nothing that comes to mind, then you must be a new learner of Java. If you got some components in your mind, you started visualizing the things in Java as an expert programmer. These are: Module, Package, Class, Variable, Statement, Method, Constructor, Inner class. Let’s talk about each one in a concise manner to make it more clear.


Module is nothing but a group of packages in java. When you develop an application you keep your java file inside a package. A group of these packages makes a module. Every real time project in java must have at least one module. In Microservice based projects, we consider a module as one microservice.


In simple terms these are group of classes. You keep multiple related java class files within a package. With the help of packages you can easily locate the classes. Suppose you are working in a Java application for the first time and you are trying to fix a bug which requires the code change for a particular functionality, there are high chances that you will go through the packages to find the classes to modify. Packages also help you to eliminate class name conflicts.


A class is a group of variables, methods, constructors, blocks & inner classes. This is the most important & mandatory part of Java application. Without existence of a class you can’t write a single useful program in Java. Also from the Object oriented language point of view you create objects with the help of a class only.


Variables provide memory for storing values like a carton in our daily life to store our valuable things. Technically a variable is a name given to a memory location. It is the basic unit of storage in a program.


Java statements are instructions that tell the programming language what to do. A basic statement, like an assignment statement, assigns a value to a variable. All Java statements must end with a semicolon (;). Other examples are like if, if-else, switch-case, break, continue etc.


Methods are used for developing logic to perform an operation like deposit, withdraw, math operations etc. They are also very important part of a program.


The primary purpose of a constructor in java is to initialize an object. Apart from that it is also used to set the values of declared variables like setter methods. If you know some basic concepts of Spring framework, you can visualize it as the constructor-injection.

Inner Class 

An Inner class is a group of variables, methods, constructors, blocks, inner classes as a separate group inside a top level class. The main advantage of using an inner class is that it can access all the members (data members and methods) of outer class including private. Apart from that it is used to develop concise, more readable and maintainable code.

What are the Essential Components Of Java Program to display some messages on a console?

There are 3 components which are essential to display a message on console like “Hello World!” which are :

1. Class
2. Main Method
3. System.out.println statement


While developing any Java Application if you have all these components in your mind you will learn java in very less time, visualize the things very easily, write code very fast, design your application quickly and now nobody can stop you to become an expert in java.




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