I have some lambas expression in my code and some try multi-catch statements and when I do gradlew build to export my mode it fails because some of the stuff I did is not supported in source 1.6. How can I use a latter version of java?

Add these lines to your build.gradle.

 

Note that ForgeGradle can't reobfuscate lambdas (see this issue), so you need to create wrapper interfaces like this one.

So I exported my mod and and I don't understand why it does not work the same between the eclipse version and the real version of minecraft?

 

I mean some things works but for example in my eclipse version I can hurt entities by doing a right click, but it does no damage when running on the real version. I think that has something to do wih server stuff. Do we have to "install server" with the forge installer?

Did you build it by running the

build

Gradle task?

 

You should create a new thread for this issue and post your code and the FML log.

CAN you require J8 in your mod? Yes.

SHOULD you? No, Minecraft targets J6, so should you. Simple as that.

I deleted my lambdas expressions and

srcCompat = JavaVersion.VERSION_1_8
targetCompat = JavaVersion.VERSION_1_8

and yes I use gradlew build.

I now have an error when I build, the error in the code is

if (amount > 0.0F && (boolean)method.invoke(attackedEntity, source))

which says "incompatible types: Object cannot be converted to boolean

 

I didn't have the problem in eclipse, but I fixed it by putting

srcCompat = JavaVersion.VERSION_1_7
targetCompat = JavaVersion.VERSION_1_7

 

in the build.gradle, it now generate the jar but the mod still act different than the eclipse one. Also I don't know where the FML log are

Casting an object to a primitive type should compile under Java 7 or 8 (and does for me), I'm not sure why it wasn't working for you.

 

You can find the FML log in <gameDirectory>/logs/fml-client-latest.log. In the development environment, <gameDirectory> is the value of the

minecraft.runDir

variable in build.gradle (defaults to run).

 

Again I suggest creating a new thread for your issue since it's likely not directly related to Java 8.