java - 如何在java中添加一个名为number Of Digits()的新方法？

Question

我有一个名为 public class ZeroCounter { 的程序。我想向其中添加一个名为 numberOfDigits() 的新方法，并在 main() 方法中添加一行来测试它。我应该怎样去做呢？下面是一小部分代码。

public class ZeroCounter   {
public static void main(String[] args)
    {
         System.out.println("Enter a nonnegative number:");
         Scanner keyboard = new Scanner(System.in);
         int number = keyboard.nextInt( ) ;

         System.out.println(number + " contains " + numberOfZeros(number) + " zeros.");
} // End of main

更新代码:

import java.util.*;

public class ZeroCounter   {
public static void main(String[] args)
    {
         System.out.println("Enter a nonnegative number:");
         Scanner keyboard = new Scanner(System.in);
         int number = keyboard.nextInt( ) ;

         System.out.println(number + " contains " + numberOfZeros(number) + " zeros.");
         int theDigit = keyboard.nextInt( ) ;    //added for the digitcount
         int digitCount = numberOfDigits(number, theDigit); 

    }// End of main

// * * * * Recursive Method * * * * 
public static int numberOfZeros(int n)  {
n = Math.abs(n); // Make sure the number is not negative. 

// 1. STOPPING CONDITION: Number has only only digit. 
if ( n < 10 )  {
    // if( n == 0 ) return 1;   else return 0;

    return n==0 ? 1:  0 ; // Conditional  operator.

} // end of the outer if block handling the stopping condition.


// 2. Else handle the case of two or more digits using recursion.
else {

    return n%10 == 0 ? 1 + numberOfZeros(n/10):  numberOfZeros(n/10) ; // Conditional  operator.


    // if (n%10 == 0) return 1 + numberOfZeros(n/10);
    // else return numberOfZeros(n/10);
} // end of outer else block 


} // end of recursive method method numberOfZeros. * * * * * * * * 


public static int numberOfDigits(int n, int digit) {
n = Math.abs(n); // Make sure the number is not negative.  
if ( n < 10 )  { 
     if( n == digit )    return 1;  
else           return 0; 
} // end of the outer if block handling the stopping condition. 
// 2. Else handle the case of two or more digits using recursion. 
else {   
      if (n%10 == digit) return 1 + numberOfDigits(n/10, digit);
        else return numberOfDigits(n/10, digit); 
} // end of outer else block 
} // end of recursive method method numberOfZeros. * * * * * * * *  
}

Answer 1

public class ZeroCounter   {
  public static void main(String[] args) {
         System.out.println("Enter a nonnegative number:");
         Scanner keyboard = new Scanner(System.in);
         int number = keyboard.nextInt( ) ;

         System.out.println(number + " contains " + numberOfZeros(number) + " zeros.");
  } // End of main

  private static int numberOfZeros(int number) {
         int result = ///// calculation
         return result;
  }
}

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