我试图实现一个打印链表内容的方法 以下是我使用的类的解释：
1）import java.util.Scanner;
import javax.swing.JOptionPane;
public class Hangman {
public static void main(String[] args) {
String playAgainMsg = "Would you like to play again?";
String pickCategoryMsg = "You've tried all the words in this category!\nWould you like to choose another category?";
int winCounter = 0, loseCounter = 0, score = 0;
String[] words;
int attempts = 0;
String wordToGuess;
boolean playCategory = true, playGame = true;
int totalCounter = 0, counter;
while (playCategory && playGame)
{
while (playCategory && playGame) {
words = getWords();
counter = 0;
while (playGame && counter < words.length) {
wordToGuess = words[counter++];
if (playHangman(wordToGuess)) {
winCounter++;
System.out.println("You win! You have won " + winCounter + " game(s)." + " You have lost " + loseCounter + " game(s).");
} else {
loseCounter++;
System.out.println("You lose! You have lost " + loseCounter + " game(s)." + " You have won " + winCounter + " game(s).");
}
if (counter < words.length) playGame = askYesNoQuestion(playAgainMsg);
}
if (playGame) playCategory = askYesNoQuestion(pickCategoryMsg);
}
}
}
public static boolean playHangman(String wordToGuess) {
String[] computerWord = new String[wordToGuess.length()];
String[] wordWithDashes = new String[wordToGuess.length()];
for (int i = 0; i < computerWord.length; i++) {
computerWord[i] = wordToGuess.substring(i, i+1);
wordWithDashes[i] = "_";
}
Scanner in = new Scanner(System.in);
int attempts = 0, maxAttempts = 7;
boolean won = false;
int points = 0;
while (attempts < maxAttempts && !won) {
String displayWord = "";
for (String s : wordWithDashes) displayWord += " " + s;
System.out.println("\nWord is:" + displayWord);
System.out.print("\nEnter a letter or guess the whole word: ");
String guess = in.nextLine().toLowerCase();
if (guess.length() > 1 && guess.equals(wordToGuess)) {
won = true;
} else if (wordToGuess.indexOf(guess) != -1) {
boolean dashes = false;
for (int i = 0; i < computerWord.length; i++) {
if (computerWord[i].equals(guess)) wordWithDashes[i] = guess;
else if (wordWithDashes[i].equals("_")) dashes = true;
}
won = !dashes; // If there are no dashes left, the whole word has been guessed
} else {
drawHangmanDiagram(attempts);
System.out.println("You've used " + ++attempts + " out of " + maxAttempts + " attempts.");
}
}
int score = 0;
score = scoreGame(attempts);
System.out.println("Your score is: " + score);
return won;
}
//should take in a failure int from the main method that increments after every failed attempt
public static void drawHangmanDiagram(int failure)
{
if (failure == 0)
System.out.println("\t+--+\n\t| |\n\t|\n\t|\n\t|\n\t|\n\t|\n\t|\n\t+--");
else if (failure == 1)
System.out.println("\t+--+\n\t| |\n\t| @\n\t|\n\t|\n\t|\n\t|\n\t|\n\t+--");
else if (failure == 2)
System.out.println("\t+--+\n\t| |\n\t| @\n\t| /\n\t|\n\t|\n\t|\n\t|\n\t+--");
else if (failure == 3)
System.out.println("\t+--+\n\t| |\n\t| @\n\t| / \\\n\t|\n\t|\n\t|\n\t|\n\t+--");
else if (failure == 4)
System.out.println("\t+--+\n\t| |\n\t| @\n\t| /|\\\n\t| |\n\t|\n\t|\n\t|\n\t+--");
else if (failure == 5)
System.out.println("\t+--+\n\t| |\n\t| @\n\t| /|\\\n\t| |\n\t| /\n\t|\n\t|\n\t+--");
else if (failure == 6)
System.out.println("\t+--+\n\t| |\n\t| @\n\t| /|\\\n\t| |\n\t| / \\\n\t|\n\t|\n\t+--");
}
// Asks user a yes/no question, ensures valid input
public static boolean askYesNoQuestion(String message) {
Scanner in = new Scanner(System.in);
boolean validAnswer = false;
String answer;
do {
System.out.println(message + " (Y/N)");
answer = in.nextLine().toLowerCase();
if (answer.matches("[yn]")) validAnswer = true;
else System.out.println("Invalid input! Enter 'Y' or 'N'.");
} while (!validAnswer);
return answer.equals("y");
}
public static boolean askForCategory(int category) {
Scanner in = new Scanner(System.in);
boolean validAnswer = false;
String answer;
do {
System.out.println("\nWould you like to play again? (Y/N)");
answer = in.nextLine().toLowerCase();
if (answer.matches("[yn]")) validAnswer = true;
else System.out.println("Invalid input! Enter 'Y' or 'N'.");
} while (!validAnswer);
return answer.equals("y");
}
// Asks the user to pick a category
public static String[] getWords() {
String[] programming = {"java", "pascal", "python", "javascript", "fortran", "cobol"};
String[] sports = {"gymnastics", "badminton", "athletics", "soccer", "curling", "snooker", "hurling", "gaelic", "football", "darts"};
String[] result = {""};
Scanner in = new Scanner(System.in);
boolean validAnswer = false;
String answer;
do {
System.out.println("Pick a category:\n1. Programming\n2. Sports");
answer = in.nextLine().toLowerCase();
if (answer.matches("[1-2]")) validAnswer = true;
else System.out.println("Invalid input! Enter the number of the category you want.");
} while (!validAnswer);
int selection = Integer.parseInt(answer);
switch (selection) {
case 1: result = randomOrder(programming); break;
case 2: result = randomOrder(sports); break;
}
return result;
}
// Sorts a String array in random order
public static String[] randomOrder(String[] array) {
int[] order = uniqueRandoms(array.length);
String[] result = new String[array.length];
for (int i = 0; i < order.length; i++) {
result[i] = array[order[i]];
}
return result;
}
// Generates an array of n random numbers from 0 to n-1
public static int[] uniqueRandoms(int n) {
int[] array = new int[n];
int random, duplicateIndex;
for (int i = 0; i < n; ) {
random = (int) (Math.random() * n);
array[i] = random;
for (duplicateIndex = 0; array[duplicateIndex] != random; duplicateIndex++);
if (duplicateIndex == i) i++;
}
return array;
}
public static int scoreGame(int attempts)
{
int score = 0;
switch (attempts)
{
case 0: score = 70; break;
case 1: score = 60; break;
case 2: score = 50; break;
case 3: score = 40; break;
case 4: score = 30; break;
case 5: score = 20; break;
case 6: score = 10; break;
case 7: score = 0; break;
}
return score;
}
}
和NonEmptyListNode继承EmptyListNode
2）尾随节点用AbstractListNode表示。
我实际上已经实现了它，但是，由于我被告知EmptyListNode关键字不好，我感觉很糟糕。以下是我的问题：
1）我可以在没有instanceof关键字的情况下实现toString（）吗？
2）我能以递归方式实现toString（）吗？
这是我的代码：
instanceof答案 0 :(得分：1)
您可以替换
iter instanceof NonemptyListNode
与
iter.isNonEmpty()
或
!iter.isEmpty()
这会为true
NonemptyListNode