Interpreting java.lang.NoSuchMethodError message
From section 4.3.2 of the JVM Spec:
Character Type Interpretation ------------------------------------------ B byte signed byte C char Unicode character D double double-precision floating-point value F float single-precision floating-point value I int integer J long long integer L<classname>; reference an instance of class S short signed short Z boolean true or false [ reference one array dimension
From section 4.3.3, Method descriptors:
A method descriptor represents the parameters that the method takes and the value that it returns:
MethodDescriptor:
( ParameterDescriptor* ) ReturnDescriptor
Thus,
(ILcom/sun/javadoc/ClassDoc;Lcom/sun/javadoc/MemberDoc;Ljava/lang/String;Z)
Ljava/lang/String;
translates to:
A method with int
, ClassDoc
, MemberDoc
, String
and boolean
as parameters, and which returns a String
. Note that only reference parameters are separated with a semicolon, since the semicolon is part of their character representation.
So, to sum up:
Why there are four types in parentheses (ILcom/sun/javadoc/ClassDoc;Lcom/sun/javadoc/MemberDoc;Ljava/lang/String;Z) and one after the parentheses Ljava/lang/String; when the method printDocLinkForMenu clearly has five parameters?
There are five parameters (int, ClassDoc, MemberDoc, String, boolean) and one return type (String).
What does "ILcom" or "Z" mean?
Those are mapping types for native types. You can find an overview here.
Native Type | Java Language Type | Description | Type signature ---------------+--------------------+------------------+---------------- unsigned char | jboolean | unsigned 8 bits | Z signed char | jbyte | signed 8 bits | B unsigned short | jchar | unsigned 16 bits | C short | jshort | signed 16 bits | S long | jint | signed 32 bits | I long long | jlong | signed 64 bits | J __int64 | | | float | jfloat | 32 bits | F double | jdouble | 64 bits | D
In addition, the signature
"L fully-qualified-class ;"
would mean the class uniquely specified by that name; e.g., the signature"Ljava/lang/String;"
refers to the classjava.lang.String
. Also, prefixing[
to the signature makes the array of that type; for example,[I
means the int array type.
As to your next question:
Why there are four types in parentheses (ILcom/sun/javadoc/ClassDoc;Lcom/sun/javadoc/MemberDoc;Ljava/lang/String;Z) and one after the parentheses Ljava/lang/String; when the method printDocLinkForMenu clearly has five parameters?
Because you're not running the code you think you're running. The actually running code is trying to call exactly that method described in the error message, with actually five parameters (the I
should be counted separately) and a String
return type, but this method doesn't exist in the runtime classpath (while it was available in the compiletime classpath), hence this error. Also see the NoSuchMethodError
javadoc:
Thrown if an application tries to call a specified method of a class (either static or instance), and that class no longer has a definition of that method.
Normally, this error is caught by the compiler; this error can only occur at run time if the definition of a class has incompatibly changed.
So, verify if you're actually running the right version of the code as you've posted in your question and are using the right dependencies in the runtime classpath and not having duplicate different versioned libraries in the classpath.
Update: the exception signifies that the actual code is (implicitly) trying to use the method like as follows:
String s = printDocLinkForMenu(context, cd, (MemberDoc) emd, name, false);
Because it is expecting a String
outcome while it is declared void
.