/tutorial/external/Java/example4.e

  1class EXAMPLE4
  2	-- Compilation:
  3	--    compile_to_jvm example4
  4	--    javac BSimple.java
  5	-- Execution:
  6	--    java example4
  7	-- This example demonstrates how to catch exceptions in Eiffel that were
  8	-- thrown in an external Java object.
  9
 10creation {ANY}
 11	make
 12
 13feature {ANY}
 14	make is
 15		local
 16			a1: POINTER; b: BOOLEAN; i: INTEGER; d: DOUBLE
 17		do
 18			-- create new BSimple instance
 19			a1 := new_BSimple -- get the instance variable theInteger
 20			i := get_theInteger(checkcast_BSimple(a1))
 21			io.put_string("value of theInteger: " + i.to_string + "%N")
 22			-- call proc with argument 13
 23			call_proc(a1, 13)
 24			-- get the instance variable theInteger
 25			i := get_theInteger(checkcast_BSimple(a1))
 26			io.put_string("value of theInteger after calling proc: " + i.to_string + "%N")
 27			-- call proc again with argument -11
 28			call_proc(a1, -11)
 29			-- get the instance variable theInteger
 30			i := get_theInteger(checkcast_BSimple(a1))
 31			io.put_string("value of theInteger after calling proc: " + i.to_string + "%N")
 32		end
 33
 34feature {ANY}
 35	call_proc (a1: POINTER; i: INTEGER) is
 36		local
 37			e: POINTER; javaString: POINTER; javaStringBytes: POINTER; string_length: INTEGER; s: STRING
 38			flag: BOOLEAN
 39		do
 40			if flag = False then
 41				-- call proc with argument i if not in retry
 42				proc(checkcast_BSimple(a1), i)
 43			end
 44		rescue
 45			-- get the exception and print out its message
 46			e := get_exception
 47			javaString := getMessage(checkcast_java_lang_Exception(e))
 48			string_length := length(checkcast_java_lang_String(javaString))
 49			create s.make_filled('%U', string_length)
 50			javaStringBytes := getBytes(checkcast_java_lang_String(javaString))
 51			arraycopy(javaStringBytes, 0, s.to_external, 0, string_length)
 52			io.put_string("Exception was thrown: " + s + "%N")
 53			flag := True
 54			retry
 55		end
 56
 57feature {ANY} -- externals
 58	new_BSimple: POINTER is
 59		external "Java class BSimple new ()"
 60		end
 61
 62	checkcast_BSimple (p: POINTER): POINTER is
 63		external "Java class BSimple checkcast"
 64		end
 65
 66	get_theStaticInteger: INTEGER is
 67		external "Java class BSimple get field static int theStaticInteger"
 68		end
 69
 70	set_theStaticInteger (a: INTEGER) is
 71		external "Java class BSimple set field static int theStaticInteger"
 72		end
 73
 74	get_theInteger (p: POINTER): INTEGER is
 75		external "Java class BSimple get field int theInteger"
 76		end
 77
 78	set_theInteger (p: POINTER; a: INTEGER) is
 79		external "Java class BSimple set field int theInteger"
 80		end
 81
 82	proc (p: POINTER; a: INTEGER) is
 83		external "Java class BSimple method void proc(int)"
 84		end
 85
 86	get_exception: POINTER is
 87		external "Java exception java.lang.Exception get"
 88		end
 89
 90	getMessage (p: POINTER): POINTER is
 91		external "Java class java.lang.Exception method java.lang.String getMessage()"
 92		end
 93
 94	checkcast_java_lang_Exception (p: POINTER): POINTER is
 95		external "Java class java.lang.Exception checkcast"
 96		end
 97
 98	checkcast_java_lang_String (p: POINTER): POINTER is
 99		external "Java class java.lang.String checkcast"
100		end
101
102	length (p: POINTER): INTEGER is
103		external "Java class java.lang.String method int length()"
104		end
105
106	getBytes (p: POINTER): POINTER is
107		external "Java class java.lang.String method byte[] getBytes()"
108		end
109
110	arraycopy (a1: POINTER; a2: INTEGER; a3: POINTER; a4: INTEGER; a5: INTEGER) is
111		external "Java class java.lang.System method static void arraycopy(java.lang.Object,int,java.lang.Object,int,int)"
112		end
113
114end -- class EXAMPLE4