Our Approach

SEC

In this section we present our solution for static compilers to support Java binary compatibility. Table 1 and Table 2 summarize all the binary changes to classes and interfaces specified in Chapter 13 of the Java language specification [12]. Compatible changes are marked with ``$+$'' and incompatible changes are marked with ``$-$''. We present the solutions for these changes in the coming subsections. In these tables, SEC x means the solution is presented in Section x. The symbol ``$trivial$'' is only used for binary compatible changes. It means that the solution is trivial and requires no change to the existing implementation. The numbers associated with each binary change are used for cross-referencing in later sections.

Table 1: Java binary compatibility summary: classes.

No.	$+$/$-$	Binary Change to Class	Solution
1	$+$	adding(overriding) method/constructor (without modifier change)	SEC 4.1
2	$+$	changing hierarchy preserving super(s)	SEC 4.1
3	$+$	adding field (without modifier change)	SEC 4.2
4	$+$	abstract -> nonabstract
5	$+$	final -> nonfinal
6	$+$	nonpublic -> public
7	$+$	allowing more access to member
8	$+$	final field -> nonfinal field
9	$+$	adding/deleting transient modifier
10	$+$	changing formal parameter name of method/constructor
11	$+$	abstract method -> nonabstract
12	$+$	final method -> nonfinal; nonfinal static meth -> final static
13	$+$	changing synchronized modifier
14	$+$	changing throws clause
15	$+$	changing method/constructor body
16	$+$	adding method/constructor that overloads existing one
17	$+$	changing static initializer
18	$-$	removing method/constructor	SEC 4.1
19	$-$	removing field	SEC 4.2
20	$-$	changing hierarchy without preserving super(s)	SEC 4.4.1
21	$-$	noncircular hierarchy -> circular hierarchy	SEC 4.4.1
22	$-$	nonfinal -> final	SEC 4.4.1
23	$-$	nonabstract -> abstract	SEC 4.4.1
24	$-$	nonfinal virtual method -> final virtual	SEC 4.4.2
25	$-$	restricting access to member	SEC 4.4.2
26	$-$	nonfinal field -> final field	SEC 4.4.2
27	$-$	static <-> instance member	SEC 4.4.2
28	$-$	nonabstract method -> abstract	SEC 4.4.2
29	$-$	public -> nonpublic	SEC 4.4.2
30	$+$/$-$	adding(overriding) method (with modifier change)	4.4.3
31	$+$/$-$	adding field (with modifier change)	4.4.3
32	$+$/$-$	changing signature	4.4.3
33	$+$/$-$	about native methods	4.4.3

Table 2: Java binary compatibility summary: interfaces.

No.	$+$/$-$	Binary Change to Interface	Solution
34	$+$	changing hierarchy preserving super(s)	SEC 4.3
35	$+$	nonpublic -> public
36	$+$	adding/deleting transient modifier
37	$+$	changing formal parameter name of method
38	$+$	changing synchronized modifier
39	$+$	adding method that overloads existing one
40	$-$	removing member	SEC 4.3
41	$-$	changing hierarchy without preserving super(s)	SEC 4.4.1
42	$-$	public -> nonpublic	SEC 4.4.2
43	$+$/$-$	adding field	SEC 4.2
			SEC 4.4.3
44	$+$/$-$	adding method	SEC 4.3
			SEC 4.4.3
45	$+$/$-$	changing signature	SEC 4.4.3