????3. x??????д????δ??
???????????????????null???????????????????????洢λ?ü???????????????(?????)?????????Щ??????x?????????е?????????
??????????   JVM ???????????  ?? ????????????????????????????????????????е??????????????????????????.
???????????: ???????????????????x????????????????????.
??????????д???淶??????У?????
????private String x = null;
????????? private ????д?????????????????????????????????????
?????ο?????:
????1. Variables?? Operators?? and Expressions
????2. Variable
????3. JVM Specifications
??????????:
????Java ??????????е??
????Declaration?? Initialization and Scoping for Java
????Notes from “Sun Certified Programmer for Java 6 Study Guide”
????String is passed by “reference” in Java