java - 识别数组中未使用的字母

Question

我正在用Java编写一个刽子手程序，但我遇到的问题是，在游戏中我想显示猜测的字母中剩余的字母，为此我创建了一个字符串alpha，其中包含字母表，并且我将其放入 ArrayList 中，这样我就可以选择玩家猜测的字母。但我陷入了困境，我想要得到的输出如下:并且我也附上了我为该函数编写的代码。

您还剩 6 个猜测。可用字母:abcdefghijklmnopqrstuvwxyz请猜一个字母:a

猜测不错:a_ _

您还剩 6 个猜测。可用字母:bcdefghijklmnopqrstuvwxyz

代码:

public String getRemainingLetters(String[] lettersGuessed) {

    String alpha = "abcdefghijklmnopqrstuvwxyz";        
    String [] alpha2 = alpha.split("");          
    ArrayList<String> list = new ArrayList<>(Arrays.asList(alpha2));

    return null;
    // TODO: Fill in your code here
}

Answer 1

List#removeAll & String#join

如下所示使用它们来解决问题:

static String getRemainingLetters(String[] lettersGuessed) {
    String alpha = "abcdefghijklmnopqrstuvwxyz";
    String[] alpha2 = alpha.split("");
    List<String> list = new ArrayList<>(Arrays.asList(alpha2));
    List<String> toBeRemoved = new ArrayList<>(Arrays.asList(lettersGuessed));
    list.removeAll(toBeRemoved);
    return String.join("", list);
}

演示:

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class Main {
    public static void main(String[] args) {
        // Tests
        System.out.println(getRemainingLetters(new String[] { "a", "b", "c" }));
        System.out.println(getRemainingLetters(new String[] { "d" }));
        System.out.println(getRemainingLetters(new String[] { "x", "y", "z" }));
        System.out.println(getRemainingLetters(new String[] { "x" }));
    }

    static String getRemainingLetters(String[] lettersGuessed) {
        String alpha = "abcdefghijklmnopqrstuvwxyz";
        String[] alpha2 = alpha.split("");
        List<String> list = new ArrayList<>(Arrays.asList(alpha2));
        List<String> toBeRemoved = new ArrayList<>(Arrays.asList(lettersGuessed));
        list.removeAll(toBeRemoved);
        return String.join("", list);
    }
}

输出:

defghijklmnopqrstuvwxyz
abcefghijklmnopqrstuvwxyz
abcdefghijklmnopqrstuvw
abcdefghijklmnopqrstuvwyz

交互式演示:

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        StringBuilder consumed = new StringBuilder();
        final int NO_OF_GUESSES = 6;
        Scanner kb = new Scanner(System.in);
        String guess;
        for (int i = 1; i <= NO_OF_GUESSES; i++) {
            System.out.println("Available letters: " + getRemainingLetters(consumed.toString().split("")));
            System.out.print("Guess a letter: ");
            guess = kb.nextLine();
            consumed.append(guess.length() >= 1 ? guess.charAt(0) : "");
            System.out.printf("You have %d chances left%n", NO_OF_GUESSES - i);
        }
    }

    static String getRemainingLetters(String[] lettersGuessed) {
        String alpha = "abcdefghijklmnopqrstuvwxyz";
        String[] alpha2 = alpha.split("");
        List<String> list = new ArrayList<>(Arrays.asList(alpha2));
        List<String> toBeRemoved = new ArrayList<>(Arrays.asList(lettersGuessed));
        list.removeAll(toBeRemoved);
        return String.join("", list);
    }
}

示例运行:

Available letters: abcdefghijklmnopqrstuvwxyz
Guess a letter: a
You have 5 chances left
Available letters: bcdefghijklmnopqrstuvwxyz
Guess a letter: x
You have 4 chances left
Available letters: bcdefghijklmnopqrstuvwyz
Guess a letter: