/**  * Run-Length编码（游长编码）  * @author will  *  */ public class RunLengthEncoder {  public static void main(String[] args) {     String input = "0";   System.out.println("Original String Length: " + input.length());   String encodedStr = encode(input);   System.out.println("Encoded String: " + encodedStr);   System.out.println("Encoded String Length: " + encodedStr.length());   String decodedStr = decode(encodedStr);   System.out.println("Decoded String: " + decodedStr);  }  /**   * 用Run-Length算法编码字符串   * @param sourceStr 原始字符串   * @return   */  public static String encode(String sourceStr) {   if(sourceStr == null || sourceStr.length() <= 1) {    return sourceStr;   }   int len = sourceStr.length();   StringBuilder resultBuilder = new StringBuilder();   for(int i = 0; i < len; i++) {    char cur = sourceStr.charAt(i);    int runLength = 1;    while((i+1) < len && sourceStr.charAt(i+1) == cur) {     i++;     runLength++;    }    if(runLength > 1) {     resultBuilder.append(runLength + "" + cur);    }    else {     resultBuilder.append(cur);    }   }   return resultBuilder.toString();  }  /**   * 解码Run-Length编码的字符串   * @param encodedStr   * @return   */  public static String decode(String encodedStr) {   if(encodedStr == null || encodedStr.length() <= 1) {    return encodedStr;   }   int len = encodedStr.length();   StringBuilder resultBuilder = new StringBuilder();   for(int i = 0; i < len; i++) {    char curChar = encodedStr.charAt(i);    if(Character.isDigit(curChar)) {     i++;     char nextChar = encodedStr.charAt(i);     int runLength = Integer.parseInt(curChar + "");     for(int j = 0; j < runLength; j++) {      resultBuilder.append(nextChar);     }    }    else {     resultBuilder.append(curChar);    }   }   return resultBuilder.toString();  } }