DZone Snippets: Archanciel's Code Snippets

Printing out a Map in sorted order

Archanciel (Jean-Pierre Schnyder) — Thu, 27 Mar 2008 09:09:50 GMT

// print out a Map in sorted order of its keys



    public static String dumpToString(Map map) {

        if (map == null) {

            return Constants.EMPTY_STRING;

        }



        StringBuffer strbuf = new StringBuffer();



        SortedMap sMap = new TreeMap(map);

        Set> s = sMap.entrySet();



        for (Map.Entry elem : s) {

            String key = elem.getKey();

            Object value = elem.getValue();

            strbuf.append(key);

            strbuf.append("=");

            strbuf.append(value == null ? Constants.EMPTY_STRING : value);

            strbuf.append("\r\n");

        }



        return strbuf.toString();

    }

Recursively dump imbricated Map of Maps

Archanciel (Jean-Pierre Schnyder) — Wed, 12 Sep 2007 12:58:09 GMT

// description of your code here



    public void dumpMapOfMap(Map map) {

        Set s = map.entrySet();

        Iterator sit = s.iterator();

        boolean isFirst = true;



        while (sit.hasNext()) {

            Map.Entry elem = (Map.Entry)sit.next();

            String key = (String)elem.getKey();

            Object value = elem.getValue();



            if (value instanceof String) {

                // recursivity stop condition

                System.out.print(key);

                System.out.print(" : ");

                System.out.println(value);

            } else {

                if (!isFirst) {

                    System.out.println("");

                } else {

                    isFirst = false;

                }

                System.out.println(key);

                Map valueMap = (Map)elem.getValue();

                dumpMapOfMap(valueMap);

            }

        }

    }

Obtaining the value of a public static field by reflexion

Archanciel (Jean-Pierre Schnyder) — Thu, 06 Sep 2007 14:59:06 GMT

// Obtaining the value of a static public constant of a class, here Boolean for example



        Object returnedObj = null;

        try {

            Class clazz = Class.forName("java.lang.Boolean");

            returnedObj = clazz.getField("TRUE").get(clazz);

            assert java.lang.Boolean.TRUE == returnedObj : "wrong returned object";

        } catch (ClassNotFoundException e) {

            e.printStackTrace();

        } catch (SecurityException e) {

            e.printStackTrace();

        } catch (NoSuchFieldException e) {

            e.printStackTrace();

        } catch (IllegalArgumentException e) {

            e.printStackTrace();

        } catch (IllegalAccessException e) {

            e.printStackTrace();

        }



        return returnedObj;

Printing out the full path of a resource on the classpath

Archanciel (Jean-Pierre Schnyder) — Tue, 04 Sep 2007 09:59:44 GMT

// displaying the full path of a resource found by the class loader on the classpath, here the log4j.xml file



String resourceName = "/log4j.xml"; // pay attention to the leading '/' !

URL location = AnyClass.class.getResource(resourceName);



if (location != null) {

    System.out.println(location.getPath());

} else {

    System.out.println(resourceName + " not found on the classpath");

}

Loading a text file into a String from the classpath

Archanciel (Jean-Pierre Schnyder) — Thu, 30 Aug 2007 12:48:18 GMT

Locate a text file in the classpath and read it into a String



    /** 

     * @param filePath      name of file to open. The file can reside

     *                      anywhere in the classpath

     */

    private String readFileAsString(String filePath) throws java.io.IOException {

        StringBuffer fileData = new StringBuffer(1000);

        BufferedReader reader = new BufferedReader(new InputStreamReader(this

            .getClass().getClassLoader().getResourceAsStream(filePath)));

        char[] buf = new char[1024];

        int numRead = 0;

        while ((numRead = reader.read(buf)) != -1) {

            String readData = String.valueOf(buf, 0, numRead);

            fileData.append(readData);

            buf = new char[1024];

        }

        reader.close();

        return fileData.toString();

    }

Loading a property file from the classpath

Archanciel (Jean-Pierre Schnyder) — Thu, 30 Aug 2007 12:28:02 GMT

Loads a property file located anywhere in the classpath



    private Properties getPropertiesFromClasspath(String propFileName) throws IOException {

        // loading xmlProfileGen.properties from the classpath

        Properties props = new Properties();

        InputStream inputStream = this.getClass().getClassLoader()

            .getResourceAsStream(propFileName);



        if (inputStream == null) {

            throw new FileNotFoundException("property file '" + propFileName

                + "' not found in the classpath");

        }



        props.load(inputStream);



        return props;

    }