BINARY COMPATIBILITY

Method and Constructor Declarations

13.4.12

13.4.9

static

Fields

If a field that is not declared

private

 was not declared

static

 and is changed to

be declared

static

, or vice versa, then a linkage time error, specifically an

IncompatibleClassChangeError

, will result if the field is used by a preexisting

binary which expected a field of the other kind. Such changes are not recom 

mended in code that has been widely distributed.

13.4.10

transient

Fields

Adding or deleting a

transient

 modifier of a field does not break compatibility

with pre existing binaries.

13.4.11

volatile

Fields

If a field that is not declared

private

 was not declared

volatile

 and is changed

to be declared

volatile

, or vice versa, then a linkage time error, specifically an

IncompatibleClassChangeError

, may result if the field is used by a preexisting

binary that expected a field of the opposite volatility. Such changes are not recom 

mended in code that has been widely distributed.

13.4.12   Method and Constructor Declarations

Adding a method or constructor declaration to a class will not break compatibility

with any pre existing binaries, even in the case where a type could no longer be

recompiled because a method invocation previously referenced a method of a

superclass with an incompatible type. The previously compiled class with such a

reference will continue to reference the method declared in a superclass.

Deleting a method or constructor from a class will break compatibility with

any pre existing binary that referenced this method or constructor; a

NoSuchMethodError

will be thrown when such a reference from a pre existing

binary is linked. Only

private

 methods or constructors may be safely deleted

from a widely distributed class.

If the source code for a class contains no declared constructors, the Java com 

piler automatically supplies a constructor with no parameters. Adding one or more

constructor declarations to the source code of such a class will prevent this default

constructor from being supplied automatically, effectively deleting a constructor,

unless one of the new constructors also has no parameters, thus replacing the

default constructor. The automatically supplied constructor with no parameters is

given the same access modifier as the class of its declaration, so any replacement

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