java常用方法(String)6

public static final String module = StringUtil.class.getName();

    /**
     * Replaces all occurances of oldString in mainString with newString
     * @param mainString The original string
     * @param oldString The string to replace
     * @param newString The string to insert in place of the old
     * @return mainString with all occurances of oldString replaced by newString
     */
    public static String replaceString(String mainString, String oldString, String newString) {
        if (mainString == null) {
            return null;
        }
        if (oldString == null || oldString.length() == 0) {
            return mainString;
        }
        if (newString == null) {
            newString = "";
        }

        int i = mainString.lastIndexOf(oldString);

        if (i < 0) return mainString;

        StringBuffer mainSb = new StringBuffer(mainString);

        while (i >= 0) {
            mainSb.replace(i, i + oldString.length(), newString);
            i = mainString.lastIndexOf(oldString, i - 1);
        }
        return mainSb.toString();
    }

    /**
     * Creates a single string from a List of strings seperated by a delimiter.
     * @param list a list of strings to join
     * @param delim the delimiter character(s) to use. (null value will join with no delimiter)
     * @return a String of all values in the list seperated by the delimiter
     */
    public static String join(List list, String delim) {
        if (list == null || list.size() < 1)
            return null;
        StringBuffer buf = new StringBuffer();
        Iterator i = list.iterator();

        while (i.hasNext()) {
            buf.append((String) i.next());
            if (i.hasNext())
                buf.append(delim);
        }
        return buf.toString();
    }
    public static String join(String prefix,List list, String delim) {
        if (list == null || list.size() < 1)
            return null;
        StringBuffer buf = new StringBuffer();
        Iterator i = list.iterator();

        while (i.hasNext()) {
        buf.append(prefix);
            buf.append((String) i.next());
            if (i.hasNext())
                buf.append(delim);
        }
        return buf.toString();
    }   

    /**
     * Splits a String on a delimiter into a List of Strings.
     * @param str the String to split
     * @param delim the delimiter character(s) to join on (null will split on whitespace)
     * @return a list of Strings
     */
    public static List split(String str, String delim) {
        List splitList = null;
        StringTokenizer st = null;

        if (str == null)
            return splitList;

        if (delim != null)
            st = new StringTokenizer(str, delim);
        else
            st = new StringTokenizer(str);

        if (st != null && st.hasMoreTokens()) {
            splitList = new ArrayList();

            while (st.hasMoreTokens())
                splitList.add(st.nextToken());
        }
        return splitList;
    }

    /**
     * Encloses each of a List of Strings in quotes.
     * @param list List of String(s) to quote.
     */
    public static List quoteStrList(List list) {
        List tmpList = list;

        list = new ArrayList();
        Iterator i = tmpList.iterator();

        while (i.hasNext()) {
            String str = (String) i.next();

            str = "'" + str + "'";
            list.add(str);
        }
        return list;
    }