“ <identifier> Java中出现“预期的”编译错误

Question

I get " <identifier> expected " error on this line....

  private static String getReducedISBN(char 'x') {

...of this code....

public class CheckISBN7 {

//private static String originalISBN;  // class variable

public static void main(String[] args) {
    // Prompt the user to enter an ISBN
    SimpleIO.prompt("Enter ISBN: ");
    String originalISBN = SimpleIO.readLine();

    // Get the ISBN number without the dashes
    String reducedISBN = getReducedISBN('-');

    // Get the computed check digit
    int computedCheckDigit = getCheckDigit(reducedISBN);

    // Display check digit entered by the user
    System.out.println("Check digit entered: " + originalISBN.charAt(12));

    // Display computed check digit
    System.out.println("Check digit computed: " + computedCheckDigit);
}

private static String getReducedISBN(char 'x') {
    SimpleIO.prompt("Enter ISBN: ");
    String originalISBN = SimpleIO.readLine();
    int dashPos1 = originalISBN.indexOf("x");
    int dashPos2 = originalISBN.indexOf("x", dashPos1 + 1);
    String reducedISBN = originalISBN.substring(0, dashPos1) +
            originalISBN.substring(dashPos1 + 1, dashPos2) +
            originalISBN.substring(dashPos2 + 1, 11);
    return reducedISBN;
}

private static int getCheckDigit(String reducedISBNParameter) {
    int total = 0;
    final String digits = "0123456789X";
    for(int i = 0, j = 10; i <= 8; i++, j++) {
        total += j *
                (Integer.parseInt(reducedISBNParameter.substring(i, i + 1)));
    }
    int checkDigit = 10 - ((total - 1) % 11);
    int computedCheckDigit = digits.charAt(checkDigit);
    return computedCheckDigit;
    }
}

Can't really figure out the problem , any help would be much appreciated.

Answer 1

You're trying to pass the char value 'x' in your method signature, which isn't valid syntax:

private static String getReducedISBN(char 'x') {

Did you mean to use x as a variable name?

private static String getReducedISBN(char x) {

As well as here, since I assume you're trying to find the index of whatever you pass as the separator character instead of the string "x" :

int dashPos1 = originalISBN.indexOf(x);
int dashPos2 = originalISBN.indexOf(x, dashPos1 + 1);

Answer 2

'x' is not an indentifier (variable or whatever), it is a literal character. Likewise "x" is a literal string. Replace char 'x' with Character x and "x" with x.toString() to get what you want.