feat: robusta_jni

__ffi/robusta_jni/com/example/robusta/HelloWorld.java

@@ -0,0 +1,37 @@
+package com.example.robusta;
+
+import java.util.*;
+
+class HelloWorld {
+    private static native ArrayList<String> special(ArrayList<Integer> input1, int in2);
+
+    // pub extern "java" fn staticJavaAdd(i: i32, u: i32) -> i32 {}
+    public static int staticJavaAdd(int i, int u) {
+        return i + u;
+    }
+
+    // pub extern "java" fn javaAdd(&self, i: i32, u: i32) -> i32 {}
+    public int javaAdd(int i, int u) {
+        return i + u;
+    }
+
+    public String javaAdd(String i, int f, String u) {
+            return i + u;
+    }
+
+    // pub extern "jni" fn nativeFun(self, static_call: bool) -> i32
+    public native int nativeFun(boolean staticCall);
+
+    static {
+        System.loadLibrary("robusta_jni");
+    }
+
+    public static void main(String[] args) {
+        ArrayList<String> output = HelloWorld.special(new ArrayList<Integer>(List.of(1, 2, 3)), 4);
+        System.out.println(output);
+
+        HelloWorld h = new HelloWorld();
+        System.out.println(h.nativeFun(false));
+        System.out.println(h.nativeFun(true));
+	}
+}