Java 追加时返回null的字符串
我的任务是制作一个猜字游戏。你只有5次试着猜这个词。用户一次输入一个字母，试图找出我的秘密单词“juice”，但你应该使用一个提示词构造，如果正确，每次猜测都会用正确的字母替换星号 输出应该是这样的：Java 追加时返回null的字符串,java,Java,我的任务是制作一个猜字游戏。你只有5次试着猜这个词。用户一次输入一个字母，试图找出我的秘密单词“juice”，但你应该使用一个提示词构造，如果正确，每次猜测都会用正确的字母替换星号 输出应该是这样的： public class SecretWord { private String secretWord; private String hintWord; private int numberOfTurns; //Default Constructors public SecretWord()
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;
}
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!");
}
猜一个小写字母 u *u*** 猜猜这个秘密 塔特尔 继续努力 猜一个小写字母 t *u*** 猜猜这个秘密 突变 继续努力 。。。持续5次，然后你要么赢，要么输 我的输出不允许您尝试猜测，提示词显然是乱七八糟的，因为它在5个星号的前面是空的。。我不知道如何修复它。 当前的提示是 空的***** 猜一个小写字母 j 七月* 猜猜这个秘密 朱特 继续努力 游戏结束！再试一次 这是我的班级：
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;
}
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!");
}
公共类SecretWord{
私密字串；
私人字符串hintWord；
私人整数匝数；
//默认构造函数
公开密文（）
{
this.secretWord=“juice”；
for（int i=0；iSecretWord
的hintword
默认初始化为null
。因此，当您向其追加+=“*”
时，它会将当前值转换为“null”
，然后添加“*”
。如果您在声明它的位置初始化hintword
它会解决这个问题。在SecretWord
类中，您不会初始化hintWord
因此，当执行hintWord+=“*”；
时，hintWord为null
，然后隐式转换为字符串“null”
，与“*”
*”连接，您应该在构造函数中使用它之前设置hintWord。将其设置为“”应该可以工作。hintWord不是null
它的“null*****”
正如您对代码的期望。如果您想知道原因，请在setHintWord（）上放置一个断点方法并逐步执行代码。@PeterLawrey你知道为什么它不会像预期的那样在5个字母的猜测后停止吗？你总是设置this.numberOfTurns=5；
，然后忽略传入的值。同样，这是你可以在调试器中看到的。你知道为什么它在5个字母的猜测后不会像预期的那样停止吗etNumberOfTurns忽略其参数i，而是始终将变量的值设置为5。它在while循环结束时被调用。这会导致while条件的下一次检查返回false，循环退出。你知道为什么它不会像预期的那样在5个字母的猜测后停止吗？@ChrisM，setNumberOfTurns（inti）
不会将
numberOfTurns`设置为
i