输出不带括号和逗号的Arraylist字符串

Question

我试图写一个程序，读取一串文本，并打印文本中的所有直方图及其频率。

输入示例：在停车场停车

相应的输出：ar:3pa:2rk:2at:1ca:1he:1in:1ki:1lo:1ng:1ot:1th:1

当我尝试这个示例输入时，它输出[ar:3，pa:2，rk:2，ca:1，at:1，th:1，he:1，ki:1，in:1，ng:1，lo:1，ot:1]

我该如何修复它，使它不会有括号和逗号？

public class Digrams {

public static void main(String args[]) {
    Scanner scan = new Scanner(System.in);

    String str = scan.nextLine();

    ArrayList<String> repetition = new ArrayList<String>();
    ArrayList<String> digrams = new ArrayList<String>();
    String digram;

    for (int i = 0; i < str.length() - 1; i++) {
        digram = str.substring(i, i + 2);
        if (repetition.contains(digram) || digram.contains(" ") || digram.length() < 2) {
            continue;
        }
        int occurances = (str.length() - str.replace(digram, "").length()) / 2;
        digrams.add(digram + ":" + occurances);
        repetition.add(digram);
    }

    Collections.sort(digrams, (s1, s2) -> s2.substring(3, 4).compareTo(s1.substring(3, 4)));

    System.out.println(digrams);
  }
}

Answer 1

这不是最有效的解决方案，但它能解决问题。

String result = digrams.toString();
System.out.println(result.replaceAll(",","").replace("[","").replace("]",""));