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