What is Java, Why one Should Learn Java
When people say “Java,” there are actually several things they might be talking about:
What is JAVA?
A Java Virtual Machine (JVM) is used to run Java programs. The JVM can be made to run on different platforms, like Linux and Windows, so the same Java programs can run on computers with different operating systems. This is the cornerstone of one of Sun’s slogans for Java: Write Once, Run Anywhere. The JVM is infrastructure, kind of like vocal cords for spoken languages.
The Java Application Programming Interfaces (APIs, or class libraries) are a set of prebuilt classes that you can use in your own programs. Essentially, this is stuff for free, like classes that deal with disk files, network sockets, or graphic interfaces. If the Java language is like a set of grammar rules in a spoken language, then the APIs are dictionaries full of words that can be used to build sentences and paragraphs and stories.
When people talk about “learning Java,” they usually mean learning the Java language and APIs. You probably won’t ever have to know much about the JVM, although a basic familiarity with it is helpful.
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