java - 只获取字符串中的每个字母一次

Question

我正在为 Horspool 算法编写 Java 程序，但遇到了一些麻烦。我正在尝试创建一个字符数组，将每个字母保存在字符串中，但我不想要重复的字母。现在这是我的代码:

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

    int count = 0;

    int count2 = 0;

    int inc = 0;

    //The text to search for the phrase in
    String t = "";

    //The phrase/pattern to search for
    String p = "";

    System.out.println(" ");
    System.out.println("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~");
    System.out.println("Harspool's Algorithm: ");
    System.out.println("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~");
    System.out.println(" ");
    System.out.println("Please enter the full text: ");
    t = scanIn.nextLine();
    System.out.println("Please enter the pattern to search for: ");
    p = scanIn.nextLine();

    char[] text = new char[t.length()];
    char[] pattern = new char[p.length()];
    char[] alphabet = new char[t.length()];

    for (int i = 0; i < alphabet.length; i++)
    {
        alphabet[i] = ' ';
    }


    for (int i = 0; i < text.length; i++)
    {
        text[i] = t.charAt(i);
    }

    for (int i = 0; i < pattern.length; i++)
    {
        pattern[i] = p.charAt(i);
    }

    while (inc < text.length)
    {
        for (int j = 0; j < text.length; j++)
        {
            if (text[inc] != alphabet[j])
            {
                count++;
            }
            if (count == p.length() - 1 && count2 < text.length)
            {
                alphabet[count2] = text[inc];
                count2++;
                count = 0;
                inc++;
            }
        }
    }

    for (int i = 0; i < alphabet.length; i++)
    {
        System.out.print(alphabet[i]);
    }
}

我相信问题出在 while 循环中，但我无法弄清楚到底出了什么问题。现在，它将打印出传入的整个字符串，而它应该只打印每个字母一次。有人可以帮忙吗？

Answer 1

不要计算每个字符的出现次数，而是使用 Set<Character> 。集合包含唯一的元素，因此这样就不会出现重复项。

您还可以转换 Set通过执行 mySet.toArray(new String[mySet.size()]); 到数组或者只是 mySet.toArray(new String[0]);