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105 lines
3.3 KiB
Plaintext
105 lines
3.3 KiB
Plaintext
[[Property:title|Eiffel2Java Sample]]
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[[Property:weight|1]]
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[[Property:uuid|90ef17d4-8e23-34dd-1cb8-488533561dd4]]
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This example shows how to create an instance of the Java Virtual Machine and the creation of an object of type <eiffel>test</eiffel>, a java class reproduced below:
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<code lang="java">
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(Java Code)
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class test
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{
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test ()
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{
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my_integer = 10;
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}
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public int my_integer;
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public static int my_static_integer;
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public void my_method (int arg_int, String arg_string)
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{
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my_static_integer = arg_int;
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my_integer = arg_int;
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}
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}
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</code>
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In order to run properly you need to read [[Eiffel2Java|the library requirement]] .
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===Compiling the example===
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Since the example is using the `test.java` class, the first step is to compile the java class using the `javac` command line utility from the JDK. Once it is done, copy the `test.class` either into $ISE_EIFFEL\examples\Eiffel2Java\EIFGENs\classic\W_code or else into $ISE_EIFFEL\examples\Eiffel2Java\EIFGENs\classic\F_code, depending on your compilation mode (freezing vs. finalizing).
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===Running the example===
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Once the example is compiled, you can run it and here is the expected output:
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<code>
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$ sample
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Creating instance of class `test'
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Value of `my_integer' is 10
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Value of `my_static_integer' is 0
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Calling `my_method' with (2, "String test")
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Value of `my_integer' after call to `my_method' is 2
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</code>
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===Code description===
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<code>(Eiffel Code)
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class
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EIFFEL_TO_JAVA
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inherit
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SHARED_JNI_ENVIRONMENT
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create
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make
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feature -- Creation
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make
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local
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class_test: JAVA_CLASS
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instance_of_class_test: JAVA_OBJECT
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fid: POINTER
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value: INTEGER
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j_args: JAVA_ARGS
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do
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--| Creation of the Java object
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class_test := jni.find_class ("test")
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create instance_of_class_test.create_instance (class_test, "()V", Void)
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--| Access to a public attribute
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fid := instance_of_class_test.field_id ("my_integer", "I")
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-- 'fid' contains the id of the field 'my_integer'
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-- 'value' contains the value of the field referenced
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-- by 'fid'
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value := instance_of_class_test.integer_attribute (fid)
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--| Access to a static attribute using directly the JAVA_CLASS
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fid := class_test.field_id ("my_static_integer", "I")
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value := class_test.integer_attribute (fid)
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--| Access to a static attribute using the attribute 'jclass'
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fid := instance_of_class_test.jclass.field_id ("my_static_integer", "I")
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value := instance_of_class_test.jclass.integer_attribute (fid)
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--| Access to the method 'my_method'
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-- Get the id of 'my_method'
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fid := instance_of_class_test.method_id ("my_method", "(ILjava/lang/String;)V")
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-- Create the set of arguments for 'my_method'
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create j_args.make(2)
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j_args.push_int (2)
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j_args.push_string("String test")
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-- Create the set of arguments for 'my_method'
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-- Call to the void method referenced by 'fid'
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instance_of_class_test.void_method (fid, j_args)
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end -- make
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end -- class EIFFEL_TO_JAVA</code>
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