java--字符串排序

字符串倒序

package cn.com.iterview.questions;
/**
 * 面试题<br>
 * 字符串倒序
 * @author wutz
 *
 */
public class StringReverse {

    public static void main(String[] args) {
        String str = "abcdef";
        //function 1将字符串的每个字符存入数组toCharArray()
        StringBuffer sb = new StringBuffer();
        char[] ch = str.toCharArray();
        for(int i = ch.length-1;i>=0;i--){
            sb.append(ch[i]);
        }

        System.out.println(sb.toString());

        //function 2方法返回指定索引处的char值。索引范围是从0到length() - 1
        StringBuffer sb1 = new StringBuffer();
        for(int i=str.length()-1;i>=0;i--){
            sb1.append(str.charAt(i));
        }
        System.out.println(sb1.toString());

        //function 3StringBuffer对象的值反转
         System.out.println(new StringBuffer(str).reverse().toString());
    }
}

对字符串按照字母表顺序排序：

        String str = "wangbao";
        char[] arr = str.toCharArray();
        Arrays.sort(arr);
        System.out.println(String.valueOf(arr));