统计字符串中各个字符的数量(提示:字符不用排序)

import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map.Entry;
import java.util.Scanner;
import java.util.Set;

/*分析以下需求,并用代码实现	
1.利用键盘录入,输入一个字符串
2.统计该字符串中各个字符的数量(提示:字符不用排序)
3.如:
	用户输入字符串"If~you-want~to~change-your_fate_I_think~you~must~come-to-the-dark-horse-to-learn-java"
	程序输出结果:-(9)I(2)_(3)a(7)c(2)d(1)e(6)f(2)g(1)h(4)i(1)j(1)k(2)l(1)m(2)n(4)o(8)r(4)s(2)t(8)u(4)v(1)w(1)y(3)~(6)*/
public class t6 {
	public static void main(String[] args) {
		//创建键盘录入对象
		Scanner sc = new Scanner(System.in);
		System.out.println("请输入一个字符串:");
		//接收字符串
		String s = sc.nextLine();
		
		//将字符串转换成数组
		char[] ch = s.toCharArray();
		
		//创建Map集合
		HashMap<Character, Integer> hm = new HashMap<Character, Integer>();
		
		//遍历字符数组
		for (int i = 0; i < ch.length; i++) {
			
			//将数组中的字符作为键去查询map表
			Integer value = hm.get(ch[i]);
			
			//判断值是否为null
			int count = 0;
			if( value != null) {
				count = value;
			}
			count++;
			hm.put(ch[i], count);
		}
		
		//遍历集合
		Set<Entry<Character, Integer>> entrys = hm.entrySet();
		for (Entry<Character, Integer> entry : entrys) {
			Character key = entry.getKey();
			Integer value = entry.getValue();
			System.out.print(key+"("+value+")");
		}
	}
}

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转载自blog.csdn.net/ludadan/article/details/79947038