It is a short side project away from the OpenCV and Processing thread. In this example, I would like to see if I can load an external class within a Processing sketch. The structure of the program is:<\/p>\n
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\nMain program<\/em>
\nTestLoad001<\/p>\n\r\nimport java.lang.reflect.Method;\r\n\r\nvoid setup() {\r\n size(640, 480);\r\n}\r\n\r\nvoid draw() {\r\n background(0);\r\n}\r\n\r\nvoid mousePressed() {\r\n MyLoader ldr = new MyLoader();\r\n Class myObj = ldr.load(\"MyTest\");\r\n Object oo;\r\n try {\r\n oo = myObj.newInstance();\r\n println(\"Class name: \" + oo.getClass().getName());\r\n Method m = oo.getClass().getMethod(\"ShowMe\");\r\n println(\"Method name: \" + m.getName());\r\n m.invoke(oo);\r\n } \r\n catch (Exception e) {\r\n e.printStackTrace();\r\n }\r\n}\r\n<\/pre>\n
\nLoader class<\/em>
\nMyLoader (a subclass of ClassLoader)<\/p>\n\r\nimport java.net.URL;\r\nimport java.net.URLConnection;\r\nimport java.io.ByteArrayOutputStream;\r\n\r\npublic class MyLoader extends ClassLoader {\r\n\r\n public MyLoader() {\r\n super();\r\n }\r\n\r\n public Class load(String _c) {\r\n try {\r\n String url = \"file:\" + dataPath(_c + \".class\");\r\n URL addr = new URL(url);\r\n URLConnection conn = addr.openConnection();\r\n\r\n InputStream in = conn.getInputStream();\r\n ByteArrayOutputStream buf = new ByteArrayOutputStream();\r\n int num = in.read();\r\n while (num != -1) {\r\n buf.write(num);\r\n num = in.read();\r\n }\r\n in.close();\r\n byte [] data = buf.toByteArray();\r\n\r\n return defineClass(\"MyTest\", data, 0, data.length);\r\n } \r\n catch (Exception e) {\r\n e.printStackTrace();\r\n }\r\n return null;\r\n }\r\n}\r\n<\/pre>\n
\nExternal class (compiled and placed inside the data folder)<\/em>
\nMyTest<\/p>\n\r\npublic class MyTest {\r\n\r\n public MyTest() {\r\n System.out.println(\"MyTest object instance created.\");\r\n }\r\n\r\n public void ShowMe() {\r\n System.out.println(\"ShowMe method called.\");\r\n }\r\n}\r\n<\/pre>\n