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require File.expand_path(File.dirname(__FILE__) + '/edgecase')
include Java
# Concepts
# * Pull in a java class
# * calling a method, Camel vs snake
# * Resolving module/class name conflicts
# * Showing what gets returned
# * Ruby Strings VS Java Strings
# * Calling custom java class
# * Calling Ruby from java???
class AboutJavaInterop < EdgeCase::Koan
def test_using_a_java_library_class
java_array = java.util.ArrayList.new
assert_equal __(Java::JavaUtil::ArrayList), java_array.class
end
def test_java_class_can_be_referenced_using_both_ruby_and_java_like_syntax
assert_equal __(true), Java::JavaUtil::ArrayList == java.util.ArrayList
end
def test_include_class_includes_class_in_module_scope
assert_nil defined?(TreeSet) # __
include_class "java.util.TreeSet"
assert_equal __("constant"), defined?(TreeSet)
end
# THINK ABOUT IT:
#
# What if we use:
#
# include_class "java.lang.String"
#
# What would be the value of the String constant after this
# include_class is run? Would it be useful to provide a way of
# aliasing java classes to different names?
JString = java.lang.String
def test_also_java_class_can_be_given_ruby_aliases
java_string = JString.new("A Java String")
assert_equal __(java.lang.String), java_string.class
assert_equal __(java.lang.String), JString
end
def test_can_directly_call_java_methods_on_java_objects
java_string = JString.new("A Java String")
assert_equal __("a java string"), java_string.toLowerCase
end
def test_jruby_provides_snake_case_versions_of_java_methods
java_string = JString.new("A Java String")
assert_equal __("a java string"), java_string.to_lower_case
end
def test_jruby_provides_question_mark_versions_of_boolean_methods
java_string = JString.new("A Java String")
assert_equal __(true), java_string.endsWith("String")
assert_equal __(true), java_string.ends_with("String")
assert_equal __(true), java_string.ends_with?("String")
end
def test_java_string_are_not_ruby_strings
ruby_string = "A Java String"
java_string = java.lang.String.new(ruby_string)
assert_equal __(true), java_string.is_a?(java.lang.String)
assert_equal __(false), java_string.is_a?(String)
end
def test_java_strings_can_be_compared_to_ruby_strings_maybe
ruby_string = "A Java String"
java_string = java.lang.String.new(ruby_string)
assert_equal __(false), ruby_string == java_string
assert_equal __(true), java_string == ruby_string
# THINK ABOUT IT:
#
# Is there any possible way for this to be more wrong?
#
# SERIOUSLY, THINK ABOUT IT:
#
# Why do you suppose that Ruby and Java strings compare like that?
#
# ADVANCED THINK ABOUT IT:
#
# Is there a way to make Ruby/Java string comparisons commutative?
# How would you do it?
end
def test_however_most_methods_returning_strings_return_ruby_strings
java_array = java.util.ArrayList.new
assert_equal __("[]"), java_array.toString
assert_equal __(true), java_array.toString.is_a?(String)
assert_equal __(false), java_array.toString.is_a?(java.lang.String)
end
def test_some_ruby_objects_can_be_coerced_to_java
assert_equal __(Java::JavaLang::String), "ruby string".to_java.class
assert_equal __(Java::JavaLang::Long), 1.to_java.class
assert_equal __(Java::JavaLang::Double), 9.32.to_java.class
assert_equal __(Java::JavaLang::Boolean), false.to_java.class
end
def test_some_ruby_objects_are_not_coerced_to_what_you_might_expect
assert_equal __(false), [].to_java.class == Java::JavaUtil::ArrayList
assert_equal __(false), {}.to_java.class == Java::JavaUtil::HashMap
assert_equal __(false), Object.new.to_java.class == Java::JavaLang::Object
end
def test_java_collections_are_enumerable
java_array = java.util.ArrayList.new
java_array << "one" << "two" << "three"
assert_equal __(["ONE", "TWO", "THREE"]), java_array.map { |item| item.upcase }
end
# ------------------------------------------------------------------
# Open the Java ArrayList class and add a new method.
class Java::JavaUtil::ArrayList
def multiply_all
result = 1
each do |item|
result *= item
end
result
end
end
def test_java_class_are_open_from_ruby
java_array = java.util.ArrayList.new
java_array.add_all([1,2,3,4,5])
assert_equal __(120), java_array.multiply_all
end
end
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