Java中的Word程序错误

Question

This is my code and it compiles fine but when I try to create a string it says Error: cannot find symbol - variable racer

 public class Word {
    private String original;

    public Word(String s) {
       original = s;
    }
    public String reverse () {
       String reverse= "";
       int x = 1;
       int length = original.length();
       while (length - x >= 0) {
        reverse = reverse + original.substring(length -x);
        x++;
       }
       return reverse;

    }
    public boolean isPalindrome() {
       if(original.equals(reverse()))
       return true;
       else
       return false;     
    }      
}

Answer 1

The stated problem is not in the code posted - my guess is irrelephant's comment is correct, ie change new Word(racer) --> new Word("racer") .

But I offer this to eliminate any chance of any errors in your code by basically eliminating your code:

public class Word {
    private String original;

    public Word(String s) {
       original = s;
    }

    public boolean isPalindrome()
        return new StringBuilder(original).reverse().toString().equals(original);
    }
}

or if you must expose a reverse() method:

public class Word {
    private String original;

    public Word(String s) {
       original = s;
    }

    public String reverse () {
        return new StringBuilder(original).reverse().toString();
    }

    public boolean isPalindrome()
        return reverse().equals(original);
    }
}

Answer 2

I don't see the variable racer anywhere, but since you're using reverse inside a method, I'd recommend making it

Most likely, racer was never defined

Either that or the method was called w/o quotes

isPalindrome(racer)//note the lack of quotes

change reverse() to this

private() String reverse () {
   String reverse= "";
   int x = 1;
   int length = original.length();
   while (length - x >= 0) {
    reverse = reverse + original.substring(length -x);
    x++;
   }
   return reverse;