Java 程序计算字符串中字符的总出现次数

编写一个 Java 程序，使用示例计算字符串中字符的总出现次数。在此字符串字符出现次数示例中，我们使用 While 循环从头到尾迭代 calStr 字符串。

在循环中，我们将每个 calStr 字符串字母 (charAt()) 与 ch 进行比较。如果它们相等，我们将 charCount 加一。最后，我们将 charCount 作为输出打印出来。

import java.util.Scanner;

public class CountAllCharOccurence1 {
	private static Scanner sc;
	public static void main(String[] args) {
		String calStr;
		char ch;
		int i = 0, charCount = 0;
		
		sc= new Scanner(System.in);

		System.out.print("\nPlease Enter String to Count all Char Occurrence =  ");
		calStr = sc.nextLine();
		
		System.out.print("\nEnter the Character to Find =  ");
		ch = sc.next().charAt(0);
		
		while(i < calStr.length())
		{
			if(calStr.charAt(i) ==  ch) {
				charCount++;
			}
			i++;
		}
		System.out.format("\nTotal Number of time %c has found =  %d ", 
				ch, charCount);	
	}
}

Java Program to Count Total Occurrence of Character in a String using while loop

Java 程序使用 for 循环计算字符串中字符的总出现次数

此字符总出现次数示例与上面相同。在此 Java 示例中，我们用 For 循环替换了 While 循环。

import java.util.Scanner;

public class CntAllChOcc32 {
	private static Scanner sc;
	public static void main(String[] args) {
		String calStr;
		char ch;
		int i, charCount = 0;
		
		sc= new Scanner(System.in);

		System.out.print("\nPlease Enter String =  ");
		calStr = sc.nextLine();
		
		System.out.print("\nEnter the Character to Find =  ");
		ch = sc.next().charAt(0);
		
		for(i = 0; i < calStr.length(); i++)
		{
			if(calStr.charAt(i) ==  ch) {
				charCount++;
			}
		}
		System.out.format("\nTotal Number of time %c has found =  %d ", 
				ch, charCount);	
	}
}

Please Enter String =  hello world

Enter the Character to Find =  l

Total Number of time l has found =  3

此程序使用函数计算字符串中字符的总出现次数。在这里，我们创建了一个 CountAllCharOcc 函数，该函数返回字符计数。

import java.util.Scanner;

public class CntAllChOcc3 {
	private static Scanner sc;
	public static void main(String[] args) {
		
		sc= new Scanner(System.in);

		System.out.print("\nPlease Enter Text =  ");
		String calStr = sc.nextLine();
		
		System.out.print("\nEnter the Letter to Find =  ");
		char ch = sc.next().charAt(0);
		
		int charCount = CntAllCharOcc(calStr, ch);
		System.out.format("\nTotal Number of time %c has found =  %d ", ch, charCount);	
	}
	
	public static int CntAllCharOcc(String calStr, char ch) {
		int i, charCount = 0;
		
		for(i = 0; i < calStr.length(); i++)
		{
			if(calStr.charAt(i) ==  ch) {
				charCount++;
			}
		}
		return charCount;
	}
}

Please Enter Text =  tutorial gateway

Enter the letter to Find =  t

Total Number of time t has found =  3

请参考以下字符串程序。