Source code in Java refers to the set of instructions or commands written by a programmer using the Java programming language. It is the fundamental component of a computer program that is created by a programmer, often written in the form of functions, descriptions, definitions, calls, methods, and other statements. Java source code is written in plain text, similar to the English language, and is easy to read and modify. Once the programmer writes the source code, it is compiled into machine-understandable code, which is called bytecode. The computer can not understand direct source code, but it can understand the bytecode and execute it.
Programmers can use a text editor, a visual programming tool, or an integrated development environment (IDE) such as a software development kit (SDK) to create source code. In large program development environments, there are often management systems that help programmers separate and keep track of different states and levels of source code files.
In summary, source code in Java is a set of instructions or commands written by a programmer using the Java programming language. It is the fundamental component of a computer program that is compiled into machine-understandable code, which is called bytecode.