format a string

StringFormatter.java

/**
 * User: walter
 * Date: 5/5/14
 * Time: 5:09 PM
 */
public class StringFormatter {

    static final String DELIM_STR = "{}";

    /**
     * Format a string. <br/>
     *
     * StringFormatter.format("/user/{}/info",123) // "/user/123/info" <br/>
     *
     * @param pattern
     * @param params
     * @return
     */
    final public static String format(final String pattern, Object... params) {

        if (pattern == null) {
            return "";
        }

        if (params == null) {
            return pattern;
        }

        int i = 0;
        int j;
        StringBuffer sbuf = new StringBuffer(pattern.length() + 50);

        int L;
        for (L = 0; L < params.length; L++) {

            j = pattern.indexOf(DELIM_STR, i);

            if (j == -1) {
                // no more variables
                if (i == 0) { // this is a simple string
                    return pattern;
                } else { // add the tail string which contains no variables and return
                    // the result.
                    sbuf.append(pattern.substring(i, pattern.length()));
                    return sbuf.toString();
                }
            } else {
                // normal case
                sbuf.append(pattern.substring(i, j));
                appendParameter(sbuf, params[L]);
                i = j + 2;
            }
        }
        // append the characters following the last {} pair.
        sbuf.append(pattern.substring(i, pattern.length()));
        if (L < params.length - 1) {
            return sbuf.toString();
        } else {
            return sbuf.toString();
        }
    }

    private static void appendParameter(StringBuffer sb, Object o) {
            String oAsString = o.toString();
            sb.append(oAsString);
    }
}