追加后返回null的字符串 [英] string returning null on append
问题描述
我受命创建一个猜词游戏.您只有5次尝试猜单词的机会.用户一次输入一个字母试图找出我的秘密单词"juice"，但是您应该使用提示单词结构，如果正确，每个猜测都会用正确的字母替换星号.
I've been tasked to create a word guessing game. You only have 5 tries to guess the word. User enters in one letter at a time to try to figure out my secret word which is "juice" but you're supposed to work with a hint word construct which each guess replaces the asterisks with the correct letter if it is correct.
输出应该是这样的:
欢迎来到猜词游戏！您有5次尝试猜出这个秘密单词的机会！当前提示是
Welcome to the word guessing game! You have 5 tries to guess the secret word! The current hint is
猜一个小写字母
u
* u ***
猜个秘密
tutre
继续尝试！
猜一个小写字母
t
* u ***
猜一个秘密的词
变种
继续尝试！
...持续进行5次尝试，然后您获胜或失败
... Continues on till 5 tries then you either win or lose
我的输出不会一直让您尝试猜测，并且提示词的前5个星号都为空，因此提示词显然被弄乱了.我不确定如何解决它.
当前提示是
null *****
null*****
猜一个小写字母
j
jull *
猜个秘密
黄麻
继续尝试！
游戏结束！再试一次?
这是我的课程:
public class SecretWord {
private String secretWord;
private String hintWord;
private int numberOfTurns;
//Default Constructors
public SecretWord()
{
this.secretWord = "juice";
for (int i = 0; i < secretWord.length(); i++)
{
this.hintWord+="*";
}
this.numberOfTurns = 0;
}
//Accessors
public String getSecretWord()
{
return this.secretWord;
}
public String getHintWord()
{
return this.hintWord;
}
public int getNumberOfTurns()
{
return this.numberOfTurns;
}
//Mutators
public void setSecretWord ()
{
this.secretWord = "juice";
}
public void setHintWord ()
{
char[] correctLetters = new char[secretWord.length()];
for (int i = 0; i<secretWord.length();i++)
{
hintWord+="*";
correctLetters[i] += '*';
}
}
public void setNumberOfTurns (int i)
{
this.numberOfTurns = 5;
}
//Methods
public void guessLetter(char guess)
{
String tempHintWord="";
for (int i = 0; i < secretWord.length(); i++)
{
if (secretWord.charAt(i) == guess)
{
tempHintWord += guess;
}
else
{
tempHintWord += hintWord.charAt(i);
}
}
hintWord = tempHintWord;
}
这是我的驾驶舱:
public class SecretWordGame {
//Constant for number of tries
public static final int NUM_TRIES = 5;
public static void main (String[] args)
{
Scanner keyboard = new Scanner(System.in);
//Starts game
boolean quit = false;
while (quit == false)
{
System.out.println("Welcome to the word guessing game! You have " +
+NUM_TRIES+" tries to guess the secret word!");
SecretWord myWord = new SecretWord();
System.out.println("The current hint is \n"+myWord.getHintWord());
while (myWord.getNumberOfTurns() <NUM_TRIES)
{
System.out.println("Guess a lowercase letter");
//Gets the first letter of what is entered
char guess = keyboard.nextLine().charAt(0);
//Updates the hint by calling guess letter method
myWord.guessLetter(guess);
System.out.println(myWord.getHintWord());
System.out.println("Guess the secret word");
String myGuess = keyboard.nextLine();
//Checks correct guess
if (myGuess.equals(myWord.getSecretWord()))
{
System.out.println("You win!");
break;
}
else
{
System.out.println("Keep trying!");
}
myWord.setNumberOfTurns(myWord.getNumberOfTurns()+1);
}
//Prompts user to play again
System.out.println("Game over! Try again?");
String userInput = keyboard.nextLine();
if(userInput.equalsIgnoreCase("no"))
{
quit = true;
}
else
{
System.out.println("Let's go again!");
}
}
System.out.println("Goodbye!");
}
推荐答案
SecretWord 的提示字词默认情况下初始化为 null .因此，当您将其附加到 + ="*" 时，会将当前值转换为"null" ，然后添加"*" .如果您在将提示词声明为" 的地方初始化提示词，它将解决此问题.
SecretWord's hintword is initialized to null by default. So when you append to it += "*" it converts the current value to "null" and then adds the "*". If you initialize hintword where you declare it to "" it will fix that issue.
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