String str = "aaaaaasssscccccdddddddwsaaasdcas"; int length = str.length(); List index = new ArrayList(); for (int i = 0; i < length - 1; i++) { if(str.charAt(i) != str.charAt(i + 1)){ index.add(i); } } if(str.charAt(length - 2) != str.charAt(length - 1)){ index.add(length - 1); } int start = 0; StringBuffer result = new StringBuffer(); for (int i = 0; i < index.size(); i++) { int end = index.get(i) + 1; if(i != 0){ start = index.get(i - 1) + 1; } String temp = str.substring(start, end); result.append(temp.charAt(0)).append(end - start); } System.out.println(result.toString());最终结果是：a6s4c5d7w1s1a3s1d1c1a1s1
