public static String removeStr(String src, String str) {

         if (src == null || str == null) return src;

         int idx = src.indexOf(str);

         if (idx == -1) return src;

         int pst = 0;

         char[] cs = src.toCharArray();

         char[] rs = new char[src.length() - str.length()];

         for (int i = 0; i < cs.length; i ++) {

             if (i >= idx && i < idx + str.length()) continue;

             rs[pst] = cs[i];

             pst ++;

         }

         return new String(rs);

     }

     public static String replaceStr(String src, String target, String replacement) {

         if (src == null || target == null || replacement == null) return src;

         int idx = src.indexOf(target);

         if (idx == -1) return src;

         int pst = 0;

         char[] cs = src.toCharArray();

         char[] rs = new char[src.length() - target.length() + replacement.length()];

         for (int i = 0; i < cs.length; i ++) {

             if (i == idx) {

                 for (char c : replacement.toCharArray()) {

                     rs[pst] = c;

                     pst ++;

                 }

                 continue;

             }

             if (i > idx && i < idx + target.length()) continue;

             rs[pst] = cs[i];

             pst ++;

         }

         return new String(rs);

     }

     /**

      *

      * @param src

      * @param target

      * @param replacement

      * @return

      */

     public static String replaceAllStr(String src, String target, String replacement) {

         if (src == null || target == null || replacement == null) return src;

         int idx = src.indexOf(target);

         if (idx == -1) return src;

         int pst = 0;

         char[] cs = src.toCharArray();

         char[] rs = new char[src.length() - target.length() + replacement.length()];

         for (int i = 0; i < cs.length; i ++) {

             if (i == idx) {

                 for (char c : replacement.toCharArray()) {

                     rs[pst] = c;

                     pst ++;

                 }

                 continue;

             }

             if (i > idx && i < idx + target.length()) continue;

             rs[pst] = cs[i];

             pst ++;

         }

         return replaceAllStr(new String(rs), target, replacement);

     }