답변:
In Java, as well as in general computing, the terms "program" and "process" refer to different concepts, and understanding the distinction between them is important.
Program
- Definition: A program is a set of instructions written in a programming language (like Java) that performs a specific task when executed. It is essentially a static entity, stored on disk as a file (e.g.,
.java source file, .class bytecode file, or .jar file).
- Characteristics:
- It is a collection of code and data that is not currently being executed.
- It can be thought of as a blueprint or recipe for performing tasks.
- A program can exist in various forms, such as source code, compiled code, or scripts.
Process
- Definition: A process is an instance of a program that is being executed by the operating system. It includes the program code, its current activity (represented by the value of the program counter and the contents of the processor's registers), and the program's current state (including memory allocation, open files, etc.).
- Characteristics:
- It is a dynamic entity, meaning it is created when a program is executed and can change state during its execution.
- A process has its own memory space, which includes the program code, data, and stack.
- Multiple processes can be created from the same program, allowing for concurrent execution.
Summary
- A program is a static set of instructions stored on disk, while a process is a dynamic instance of that program in execution.
- You can think of a program as a recipe, and a process as the actual cooking that happens when you follow that recipe.
In Java, when you compile a Java program, you create bytecode files (the program). When you run a Java application using the Java Virtual Machine (JVM), it creates a process that executes the bytecode.