java - 字符.isDigit()错误: no suitable method found for isDigit(String)

Question

Kepp 在使用 Character.isDigit() 时遇到错误

我在其他地方查找过它并在那里进行了良好的测试，但我在这里不断遇到此错误。

  Scanner scnr = new Scanner(System.in);
  boolean hasDigit;
  String passCode;

  hasDigit = false;
  passCode = scnr.next();

  hasDigit = Character.isDigit(passCode);

  if (hasDigit) {
     System.out.println("Has a digit.");
  }
  else {
     System.out.println("Has no digit.");
  }

根据扫描仪输入预期 true 或 false。不断向我抛出此错误:

CheckingPasscodes.java:12: error: no suitable method found for isDigit(String)
  hasDigit = Character.isDigit(passCode);
                      ^
method Character.isDigit(char) is not applicable
  (argument mismatch; String cannot be converted to char)
method Character.isDigit(int) is not applicable
  (argument mismatch; String cannot be converted to int)

Answer 1

方法 Character.isDigit() 接受一个 char 作为输入 - 您试图向它传递一个 String。

该错误描述了问题所在:

argument mismatch; String cannot be converted to char