java -- 计算字符串中某个字符出现的次数

import java.util.HashMap;

/**
 * 统计字符串”abadcdffbaeba”中每个字符出现了多少次，按次数排序并输出。
   	例如：c : 1，e : 1，d : 2，f : 2，b : 3，a : 4
 * @author Administrator
 *
 */
public class TestString {

	public static void main(String[] args) {
		
//		String str = "abadcdffbaeba";
		String str = "gtgtthhtreeer4rtrtrgrgrgrgswxstt";
		HashMap<Object, Integer> hashMap = new HashMap<Object, Integer>();
		for(int i=0; i< str.length(); i ++){
			char ch = str.charAt(i);
			if(ch >= 'a' && ch <= 'z' || ch <= 'A' && ch <= 'Z'){
				if(!hashMap.containsKey(ch)){
					hashMap.put(ch, 1);
				}else{
					hashMap.put(ch, hashMap.get(ch) + 1);
				}
			}
		}
		String agr[][] = new String[hashMap.size()][hashMap.size()];
		
		int h =0;
		for(Object object : hashMap.keySet()){
			System.err.println(object.toString() + "," + hashMap.get(object));
			
			agr[h][0] = object.toString();
			agr[h][1] = hashMap.get(object).toString();
			
			h++;
		}
		
		
		for (int i = 0; i < agr.length; i++) {
			for (int k = 0; k < agr.length - 1; k++) {

				if (Integer.parseInt(agr[k][1]) > Integer.parseInt(agr[k + 1][1])) {
					
                                        Object temp1 = agr[k][0];
					agr[k][0] = agr[k + 1][0];
					agr[k + 1][0] = (String) temp1;

					Object temp2 = agr[k][1];
					agr[k][1] = agr[k + 1][1];
					agr[k + 1][1] = (String) temp2;
				}

			}
			
		}
		
		for (int l = 0; l < agr.length; l++) {
			System.out.println(agr[l][0] + "------" + agr[l][1]);
		}
	
	}
}