NME Native Extension Part 1 – Android : Calling Java methods from Haxe

The JNI class (nme.JNI) allow native haxe code to call Java methods.

For static method the function call is :

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nme.JNI.createStaticMethod( package_name , "method_name" , signature )

for non-static method it’s :

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nme.JNI.createMemberMethod( package_name , "method_name" , signature )

Package name:

The package is the full class package and class name separated by slash ( example: “org.shoebox.Test” is “org/shoebox/Test” )

The signature :

The signature of the method is a string:
( mapped arguments type ) return_type

First thing to know is than the arguments type must be mapped for Java.

For the basics types just follow the following table:

For the non basic types ( by example a class instance ) the mapping is:

Lpackage/of/the/ClassName;

Some examples:

On the java side :

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static public DemoJNI getInstance( ){}

static public boolean test_ret_bool( ){}

public boolean test_method_nonstatic( i : Int , b : boolean ){}

 

On the haxe side for the statics methods :

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var f1 = nme.JNI.createStaticMethod( "org/shoebox/DemoJNI" , "getInstance" , "()Lorg/shoebox/DemoJNI;" );
var instance = f1( );
var f2 = nme.JNI.createStaticMethod "org/shoebox/DemoJNI" , "test_ret_boo" , "()Z" );
var b = f2( );

 

For member methods calls you must pass as argument the JNI class instance ( by example the result of the getInstance( ) method )

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var f3 = nme.JNI.createMemberMethod "org/shoebox/DemoJNI" , "test_method_nonstatic" , "(IZ)Z" );
f3( instance , 10 , false );

Quite easy isn’t it ? When you have understand the java mapping it’s quite easy to call any java method from Haxe.

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  • Samir Sabri

    Thanks for writing this great post, I’ve noticed that you have used createStaticMethod for test_method_nonstatic is that correct? shouldn’t you use createMemberMethod ?

    Also, its very appreciated if you write another post, Calling Haxe methods from Java, I still don’t know how to call haxe function from Java, so this would be great help :-)

    • shoeboks

      You are right ! it’s fixed !

      Bad copy paste :)

      • Samir Sabri

        Can you please point me to an example about calling Haxe methods from Java?