JNI: Create HashMap

Question

How do I create a HashMap object in JNI?

Answer 1

One may also consider alternatives to directly using JNI - e.g. tools that can generate JNI code for you. For example, JANET (disclaimer: I wrote it) allows you to embed Java code in your native methods, so creating and using a hash map is then as simple as:

... (C++ code)
`Map map = new HashMap();` // embedded Java
... (C++ code)
... const char* foo = "foo";
`map.put(#$(foo), 50);` // ["foo" -> 50]

the back-ticked statements get translated by JANET to JNI code, so you never have to worry about signatures, reference handling, exception handling, etc. yet you still get the performance of JNI.