JVM is a kind of software. As to Java program, it is shown as the computer ofsoftware with single hardware and operating system characteristic. It makes Javaprogram possess the high portability among different computer systems.

• Java 虚拟机是一种软件,对Java 程序而言,它表现为具有单一硬件和操作系统特性的软件“计算机”,它使得Java 程序在不同的计算机系统之间具备高度的可移植性。