$ JULIA_NUM_THREADS=1 JULIA_COPY_STACKS=1 julia
julia> using Pkg; Pkg.activate(; temp = true)
  Activating new project at `/tmp/jl_e6uPja`
julia> using JavaCall
 │ Package JavaCall not found, but a package named JavaCall is available from a
 │ registry. 
 │ Install package?
 │   (jl_e6uPja) pkg> add JavaCall 
 └ (y/n) [y]: y
...
julia> JavaCall.addClassPath(pwd()) # Set appropriate classpath
julia> JavaCall.addOpts("-Xmx1024M") # Use 1 GB of memory
OrderedCollections.OrderedSet{String} with 1 element:
  "-Xmx1024M"
julia> JavaCall.addOpts("-Xrs") # Disable signal handling in the JVM, reducing performance but enhancing compatability
OrderedCollections.OrderedSet{String} with 2 elements:
  "-Xmx1024M"
  "-Xrs"
julia> JavaCall.init() # Call before using `jcall` or `jfield`. Do not use this in package `__init__()` to allow other packages to add classpaths or options.
julia> jls = @jimport java.lang.System
JavaObject{Symbol("java.lang.System")}
julia> out = jfield(jls, "out", @jimport java.io.PrintStream) # Third arg is optional, but helps type stability.
JavaObject{Symbol("java.io.PrintStream")}(JavaCall.JavaLocalRef(Ptr{Nothing} @0x0000000003ecda38))
julia> jcall(out, "println", Nothing, (JString,), "Hello World")
Hello World