Question

我有这个课程，我试图用它来查找字符串中的元音数量和辅音数量。

import java.lang.String;
    public class vowelsAndConsonantsClass
    {
      private int vowels;
      private int consonants;
      public vowelsAndConsonantsClass(int vwls, int cons)
      {
        vowels = vwls;
        consonants = cons;
      }
        public void numberOfVowels(String str)
        {
          int vwls = 0;
          for(int i=0; i>str.length(); i++)
          {
            if(str.charAt(i) == 'a' || str.charAt(i) == 'e' || str.charAt(i) == 'i' || str.charAt(i) == 'o' || str.charAt(i) == 'u' || str.charAt(i) == 'y');
            vwls++;
          }
        }//end numberOfVowels 
        public void numberOfConsonants(String str)
        {
          int cons = 0;
          for(int i=0; i>=str.length(); i++)
          {
            if(str.charAt(i) != 'a' || str.charAt(i) != 'e' || str.charAt(i) != 'i' || str.charAt(i) != 'o' || str.charAt(i) != 'u' || str.charAt(i) != 'y');
            cons++;
          }
        }//end numberOfConsonants
        public int getNumberOfVowels()
        {
          return vowels;
        }
        public int getNumberOfConsonants()
        {
          return consonants;
        }
    }//end class

我在收到错误时尝试使用此测试输入。我会评论它所在的线。

import java.util.Scanner;
import java.lang.String;
public class testVowelsAndConsonants
{
  public static void main(String[] args)
  {
    Scanner keyboard = new Scanner(System.in);
    int choice;
    System.out.println("Please enter a string.");
    String str = keyboard.nextLine();
    choice = menu(keyboard);
    Character.toLowerCase(choice);
    switch(choice)
    {
      case 'a':
        System.out.println(vowelsAndConsonantsClass.getNumberOfVowels());//ERROR ON THIS LINE
        break;
      case 'b':
        break;
      case 'c':
        break;
      case 'd':
        break;
      case 'e':System.exit(0);
    }
  }
  public static int menu(Scanner keyboard)
    {
    int choice;
    System.out.println("Enter a to count the number of vowels in the string.\n"+
                       "Enter b to count the number of consonants in the string.\n"+
                       "Enter c to count both the vowels and consonants in the string.\n"+
                       "Enter d to enter another string.\n"+
                       "Enter e to Exit.\n");
    do
    {
      choice = keyboard.nextInt();
    }
    while(choice<1||choice>6);
    return choice;
  }//End menu
}

请注意，我没有100％完成测试数据。一旦我理解了错误，我就会完成它。提前谢谢。

Answer 1

您不能通过类名称（静态调用）调用非静态方法/成员。我建议你实例化该类，然后调用非静态方法：

vowelsAndConsonantsClass v = new vowelsAndConsonantsClass(0, 0);
v.numberOfVowels(str);
System.out.println(v.getNumberOfVowels());

Answer 2

您正尝试在此行上以静态方式调用非静态方法：

vowelsAndConsonantsClass.getNumberOfVowels())

根据您的需要，创建vowelsAndConsonantsClass的实例或将getNumberOfVowels标记为static。

Answer 3

System.out.println(vowelsAndConsonantsClass.getNumberOfVowels());

你可以使用类名来引用类的静态方法，就像你使用它一样

因为getNumberOfVowels()中的vowelsAndConsonantsClass不是静态的，您会收到此错误

详细了解方法依据here

Java：无法对非静态方法进行静态引用

3 个答案: