How to Run Java Program?

Last Updated on April 25, 2023 by Prepbytes

Java is a widely used programming language that is used to build a wide range of applications, from mobile applications to enterprise software. Running a Java program requires a few steps. So let us learn how to run a Java program.

How to Run Java Program?

To run a Java program, it’s important to first ensure that Java is installed on the system and that the path is correctly set. Without a properly set path, the Java program cannot be executed. We are assuming that you have installed Java properly and the path is properly set.

Here are the steps of how to run Java Programs.

• Step 1: Open the Notepad and write the Java code in the Notepad. We will use the following code for performing all other operations.

  

• Step 2: Now save the file with the name “program.java”. You can save the file with any name but you must add the “.java” extension at the end of the file name. After saving you will see a Java file in the folder as shown in the image below.

  

• Step 3: Now press the keys ALT+D, by pressing these keys you will get into the search bar as shown in the image below.

  

• Step 4: Now in this search box, enter “CMD”.

  

• Step 5: As soon as you press enter, the Command Prompt Window will get open on your screen.

  

• Step 6: Now in the command prompt window, type “javac program.java”. Since we have saved our file with the name “program.java”.

  

• Step 7: Now press enter. When you press enter the Java program will be compiled by the compiler and a “PrepBytes.class” file is generated as shown in the image. This file is named after the main class present in our program.

  

• Step 8: Now to run your Java program, we have to type “java PrepBytes” in the cmd.

  

  When we press enter, our Java program will run and we will get the output in the cmd window.

  Here in our case, we get the output as “Hello, I am PrepBuddy” on the screen.

The “javac” Command

The javac command is used to compile Java source code into bytecode that can be executed by the Java Virtual Machine (JVM). This command takes a Java source file as input and produces a corresponding class file as output.

The syntax for the javac command is:

javac FileName.java

This command will compile the source code in the file FileName.java and produce a class file with the name of the main class present in the file.

The “java” Command

Once the Java code has been compiled, it can be executed using the java command. The java command is used to launch the Java Virtual Machine and execute the compiled Java code.

The syntax for the java command is:

java FileName

This command will execute the class file FileName.class that was produced by the javac command.

Conclusion
In this article, we have discussed the stepwise process of how to run Java program. We have used the javac and java commands to compile and run the java program respectively. By following these simple steps, you can also run Java programs on your own computer.

Frequently Asked Questions(FAQs)

Here are some frequently asked questions on how to run Java program.

Ques 1. What is a Java program?
Ans. A Java program is a program written in the Java programming language that can be executed on any device that has the Java Virtual Machine (JVM) installed.

Ques 2. What is a classpath?
Ans. The classpath is an environment variable that tells the JVM where to find classes and packages that are needed to run a Java program.

Ques 3. What is the JDK?
Ans. The JDK (Java Development Kit) is a software development kit used to develop Java applications. It includes the Java compiler, the Java Virtual Machine, and other tools needed for Java development.

Ques 4. What is the JRE?
Ans. The JRE (Java Runtime Environment) is a set of tools that are needed to run Java applications. It includes the Java Virtual Machine and other tools needed to run Java programs.