Java对txt中数据的修改

Question

用java读入、修改、再把修改后的数据写入新txt，希望写入新txt的结果是所有的相邻字母对出现的次数（ab=次,ba=次,aa=次，等等），原始数据中的*和#分别表示字母串的开始和结束。
我是Java初学者，请大家帮忙，写一个可以直接运行并且初学者能读懂的代码，关键部分给出注释。感谢大家热心帮忙。

源txt部分数据（都是这种格式）：
*
a
b
#
*
a
b
b
#
*
a
a
b
c
#
*
a
c
c
b
#
*
d
#
*
a
d
b
a
d
d
c
#

Answer 1

[code="java"]
public static void main(String[] args) throws Exception {
adjacentLetters();
}

public static void adjacentLetters() throws Exception {
    String inFile = "D:\\data.txt";
    String outFile = inFile;
    BufferedReader bs = null;
    BufferedWriter bw = null;
    try{
        bs = new BufferedReader(new FileReader(new File(inFile)));
        char[] ch = new char[3];
        char c = 0;
        char oc = 0;
        Map<String, Integer> outData = new TreeMap<String, Integer>();
        String key = "";
        Integer sum = 0;
        while (bs.read(ch) != -1) {
            c = ch[0];
            if(c == '*' || c == '#'){
                oc = 0;
                continue;
            }
            if(oc == c || (oc + 1) == c || (oc - 1) == c){
                key = String.valueOf(oc) + String.valueOf(c);
                sum = outData.get(key);
                if(sum == null){
                    sum = 0;
                }
                outData.put(key, ++sum);
            }
            oc = c;
        }
        //bs.close();
        //bs = null;
        if(!outData.isEmpty()){
            //true 追加  false不追加（至文件尾）
            bw = new BufferedWriter(new FileWriter(new File(outFile), false));
            for(Entry<String, Integer> entry: outData.entrySet()){
                bw.write(entry.getKey() + ":" + entry.getValue() + "\r\n");
            }
        }
    }finally{
        if(bs != null)
            bs.close();
        if(bw != null)
            bw.close();
    }
}

[/code]