$ java -classpath $JAVA_HOME/lib/tools.jar sun.tools.javac.Main
Usage: javac <options> <source files>

where <options> includes:
  -g                     Generate all debugging info
  -g:none                Generate no debugging info
  -g:{lines,vars,source} Generate only some debugging info
  -O                     Optimize; may hinder debugging or enlarge class files
  -nowarn                Generate no warnings
  -verbose               Output messages about what the compiler is doing
  -deprecation           Output source locations where deprecated APIs are used
  -classpath <path>      Specify where to find user class files
  -sourcepath <path>     Specify where to find input source files
  -bootclasspath <path>  Override location of bootstrap class files
  -extdirs <dirs>        Override location of installed extensions
  -d <directory>         Specify where to place generated class files
  -encoding <encoding>   Specify character encoding used by source files
  -target <release>      Generate class files for specific VM version

------解决方案--------------------
哈哈，楼主的意思是想问 Java 编译器是 Java 写的，但是 Java 编译器的源代码是谁来编译的呢？

很显然，最早的 Java 编译器肯定不是 Java 编写的。

一个先有鸡，还是先有蛋的问题，呵呵。

------解决方案--------------------
探讨


无语，不知道java是c++写的吗