Add two arg jfield

Author: mkitti

src/core.jl

@@ -399,6 +399,14 @@ get_method_id(method::JMethod) = @checknull JNI.FromReflectedMethod(method)
 (m::JMethod)(obj, args...) = jcall(obj, m, args...)
 
 
+"""
+    jfield(ref, field, [fieldType])
+
+Get a pointer to a field of of a Java class or object.
+* `ref` could be a JavaObject{T} type or a JavaObject
+* `field` can be an AbstractString or JField
+* `fieldType` is a Type
+"""
 function jfield(ref, field, fieldType)
     assertroottask_or_goodenv() && assertloaded()
     jfieldID = get_field_id(ref, field, fieldType)
@@ -412,6 +420,14 @@ function jfield(ref, field)
     _jfield(_jcallable(ref), jfieldID, fieldType)
 end
 
+function jfield(ref, field::AbstractString)
+    assertroottask_or_goodenv() && assertloaded()
+    field = listfields(ref, field)[]
+    fieldType = jimport(gettype(field))
+    jfieldID = get_field_id(ref, field, fieldType)
+    _jfield(_jcallable(ref), jfieldID, fieldType)
+end
+
 function get_field_id(typ::Type{JavaObject{T}}, field::AbstractString, fieldType::Type) where T
     @checknull JNI.GetStaticFieldID(Ptr(metaclass(T)), String(field), signature(fieldType))
 end