原则上几乎任何事情，通常C

原则上几乎任何事情，通常C

来自Java文档

编译器是用Java编写的，运行时是用ANSI C编写的

这个问题的精确措辞有点误导人:它不是“JVM”或“编译器”，因为有多个JVM供应商(jrockit是一个，IBM是另一个)和多个编译器。

The Sun JVM is written in C, although this need not be the case - the JVM as it runs on your machine is a platform-dependent executable and hence could have been originally written in any language. For example, the original IBM JVM was written in Smalltalk The Java libraries (java.lang, java.util etc, often referred to as the Java API) are themselves written in Java, although methods marked as native will have been written in C or C++. I believe that the Java compiler provided by Sun is also written in Java. (Although again, there are multiple compilers out there)

这个链接应该能回答你的问题

现在编译器似乎是用Java编写的，但运行时是用ANSI C编写的

When Java was introduced by Sun Microsystem, the java compiler was written in C using some libraries from C++. As there is a concept in Compiler Design called Bootstrapping, Mostly it is used in Compiler Development, Bootstrapping is the process of writing a compiler(Or Assembler) In the source programming language which it is intended to compile. It is used to produce a self-hosting compiler. The development of compilers for new Programming languages first developed in an existing language and then rewritten in the new language and compiled by itself. That's why today, Java compiler is written in Java itself. Java Virtual Machine: Java virtual machine is an abstract machine. Like a real computing machine, It has an instruction set and manipulates various memory areas of runtime. Usually, JVM interprets the byte code into Machine code.

(有关更多信息，您可以查看此链接:https://docs.oracle.com/javase/specs/jvms/se7/html/)