IDE autocomplete does not know argument names of native methods-CodePudding

I am working on two library projects. One being a native library in c and the other a Java library that uses JNI to wrap the functions from the native library. So in total I got 3 libraries:

The native library in c (project 1)
The wrapper library in c that uses headers generated by javac (project 2)
The wrapper library in Java which I use to generate headers with (project 2)

My question relates only to project 2. To compile project 2 I use a script that runs both cmake, javac and jar in one go to generate a single jar file with all my .class and .so files. With javac I use the '-g' parameter to generate debugging info. This works fine for non-native (as in the keyword 'native', not c native) methods but it does not for native. The compiled .class files do not contain the right signature either. This is rather frustrating because when I use my libraries in another java project (project 3) I do not know what to fill in based on the helper popup IntelliJ shows. My methods look like this in Java and like this in c . Any idea if I can fix that?

Also, any idea what the term is called for changing the signature of a Java method like this? I tried to lookup my problem for a couple of days now but could not find it so I was wondering if I was using the wrong search phrases in Google.

Thanks in advance!

CodePudding user response：

It appears the names of arguments are stored as "local" variables, which is not filled in for a native method. You can get around this with a small "trampoline" method:

class Window {
    public long create(int width, int height, String title) {
        return native_create(width, height, title);
    }
    private native long native_create(int width, int height, String title);
}

which results in the following javap output:

  public long create(int, int, java.lang.String);
    descriptor: (IILjava/lang/String;)J
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=4, locals=4, args_size=4
         0: aload_0
         1: iload_1
         2: iload_2
         3: aload_3
         4: invokevirtual #7                  // Method native_create:(IILjava/lang/String;)J
         7: lreturn
      LineNumberTable:
        line 4: 0
      LocalVariableTable:
        Start  Length  Slot  Name   Signature
            0       8     0  this   LWindow;
            0       8     1 width   I
            0       8     2 height   I
            0       8     3 title   Ljava/lang/String;