Build Once, Run Anywhere - Fact or Fiction?
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4 min read May 15, 2024

Build Once, Run Anywhere - Fact or Fiction?

There must be certain apps you are used to using on multiple devices, such as your laptop and phone. Have you ever wondered how these apps have been programmed to run the same way on different operating systems and devices? What amount of work would it take to code the same app but integrate it for each device?

These were all challenges faced by software engineers, who would have to code the same app multiple times for different operating systems and devices. That is until Java introduced the concept of ‘Build Once, Run Anywhere’ or ‘Write Once, Run Anywhere (WORA)‘.

Read on to learn more about WORA and how it helps quicken software development.

What is Build Once, Run Anywhere?

WORA is a system used in Java applications that run on the Java Virtual Machine, which means a programmer can build a Java program on one system and run it on any other Java-enabled system without making adjustments to the code. Thus, a programmer could develop a program on a PC and expect it to run smoothly on any Java-operated phone without making changes to the code. 

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How is Build Once, Run Anywhere Revolutionary?

Before WORA, in programming languages like C++, the program would be converted based on the device’s hardware when the program was compiled and converted into code. Thus, if developers would run the same code on another device with different hardware that understands different commands, the code would not be able to work. Hence, developers would have to spend many hours adjusting the code for that particular hardware, and for widespread apps, this happened for countless device hardware.

WORA revolutionised this aspect of coding, as the same code could work for any different hardware as long as it was integrated with the Java Virtual Machine (JVM). In fact, ‘Build Once, Run Anywhere’ was such a success that JVM being installed on chips, devices, and other software packages became an industry standard.

What Are The Benefits of Build Once, Run Anywhere?

  • No Additional Changes Required

Since Java is based on the WORA concept, when a developer creates a program for multiple different operating systems and platforms, that code built on JVM will run the same way on other Java-integrated devices. This ensures that no adjustments will be required for other hardware. Additionally, as more devices start incorporating JVM into their chips and software, the overall system integration will be extremely efficient and time-saving for programmers.

  • Writing Code For Only Java

Since the developers have to write code for only the Java platform, they don’t need to spend time learning and implementing different types of codes for specific platforms. They can focus on learning skills related to Java.

How Does WORA Work?

A Java source file containing the program runs through the compiler, which converts it into bytecode for a neutral platform. Then, this bytecode is chosen for execution in a Java Runtime Environment, where a verifier ensures no error in the code, and a class loader loads the bytecode onto the JVM. When the code is executed, a just-in-time compiler (JIT) translates the Java bytecode into the native code specific to the platform and hardware.

Summing Up

‘Build Once, Run Anywhere’ is a technical concept associated with Java. In this concept, any code built on the Java Virtual Machine can run directly on any other device as long as it is Java-integrated. This is a revolutionary technology, as it ensures programmers don’t need to spend hours changing code for different operating systems. WORA is a leading practice in many codes and devices and has single-handedly transformed the way creating code for multiple devices is approached.

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