Compute a Java function's signature

java method-signature
Niklas R picture Niklas R · Nov 9, 2011 · Viewed 18.1k times · Source

Is there a way to compute a Java class's method's signature? A signature
like ([Ljava/lang/String;)V represents a function that takes a String[] as argument
and returns void.

What's the rule to compute the signature?

Answer

Ernest Friedman-Hill picture Ernest Friedman-Hill · Nov 9, 2011

It's always a set of parentheses enclosing type signifiers for the arguments, one after the other with no commas or anything, followed by a type signifier for the return value after the closing paren. It's pretty straightforward.

There's a table of type signatures on this page:

Signature    Java Type
Z    boolean
B    byte
C    char
S    short
I    int
J    long
F    float
D    double
V    void
L fully-qualified-class ;    fully-qualified-class
[ type   type[]

Those last two mean that to name a class, you say, for example, Ljava/lang/Object;, and to name an array of (for example) int, you say [I, and an array of array of int is [[I.

If you wanted to literally compute the signature in Java code based on reflection, it'd be simple enough; just use the table above with rules for handling objects and arrays.

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