如何修改一个芬字符串在java?

Question

所以我有这个字符串StringBuilder fenToString = new StringBuilder("1P111Pr1")

现在我怎么把它改成a = "1P3Pr1"?

i tried this

int fenNum = 0;
for(int i = 0; i < fenToString.length(); i++){
if(Character.isDigit(fenToString.charAt(i))){
fenNum += 1;
fenToString.setCharAt(i, (char)(fenNum+'0'));
}else{
fenNum = 0;
}
}

我得到"1P123Pr1"而不是"1P3Pr1"

Answer 1

要显式地说明任务:您想要将两个或多个数字的序列转换为这些数字的和。该和保证小于等于8，即也保证为个位数。

有很多方法可以做到这一点，但最接近你正在尝试的可能是:

static String normalizeFen(String fen) {
StringBuilder buf = new StringBuilder(fen);
for (int i = 1; i < buf.length(); i++) {
if (Character.isDigit(buf.charAt(i)) && Character.isDigit(buf.charAt(i - 1))) {
// Found 2 consecutive digits, so sum them
int sum = Character.digit(buf.charAt(i - 1), 10)
+ Character.digit(buf.charAt(i), 10);
buf.setCharAt(i - 1, Character.forDigit(sum, 10));
buf.deleteCharAt(i); // Remove second digit
i--; // Go back to reprocess the same index position again
}
}
return buf.toString();
}

测试

System.out.println(normalizeFen("1P111Pr1"));
System.out.println(normalizeFen("rnbqkbnr/pp1ppppp/11111111/11p11111/1111P111/11111111/PPPP1PPP/RNBQKBNR"));

输出

1P3Pr1
rnbqkbnr/pp1ppppp/8/2p5/4P3/8/PPPP1PPP/RNBQKBNR

Answer 2

可以在不删除StringBuilder中的字符的情况下转换FEN字符串:

static String fixFenString(String fen) {
// debug print
System.out.print(fen + " -> ");
StringBuilder fenToString = new StringBuilder(fen.length());
int fenNum = 0;
for (int i = 0; i < fen.length(); i++) {
if(Character.isDigit(fen.charAt(i))) {
fenNum += fen.charAt(i) - '0';
} else {
if (fenNum > 0) {
fenToString.append(fenNum);
fenNum = 0;
}
fenToString.append(fen.charAt(i));
}
}
// add last digit if available
if (fenNum > 0) {
fenToString.append(fenNum);
}
return fenToString.toString();
}

测试:

System.out.println(getFenString("1P111P11"));
System.out.println(getFenString("1P12PP1"));
System.out.println(getFenString("1P131P"));
System.out.println(getFenString("rnbqkbnr/pp1ppppp/11111111/11p11111/1111P111/11111111/PPPP1PPP/RNBQKBNR"));

输出:

1P111P11 -> 1P3P2
1P12PP1 -> 1P3PP1
1P131P -> 1P5P
rnbqkbnr/pp1ppppp/11111111/11p11111/1111P111/11111111/PPPP1PPP/RNBQKBNR ->
rnbqkbnr/pp1ppppp/8/2p5/4P3/8/PPPP1PPP/RNBQKBNR