字符串反转

Posted 2022-01-12 jxxblogs

public class TurnOver 

    public static void main(String[] args) 
        String str = "abcdefg";
        System.out.println("方法1：" + turnOver1(str));
        System.out.println("方法2：" + turnOver2(str));
        System.out.println("方法3：" + turnOver3(str));
    

    /**
     * 使用递归
     *
     * @param str
     * @return
     */
    private static String turnOver1(String str) 
        if (str == null || str.length() <= 1) 
            return str;
        
        return turnOver1(str.substring(1)) + str.charAt(0);
    

    /**
     * 将字符串转换为数组，将数组倒序
     *
     * @param str
     * @return
     */
    private static String turnOver2(String str) 
        char[] arr = str.toCharArray();
        String result = "";
        for (int i = arr.length - 1; i >= 0; i--) 
            result += arr[i];
        
        return result;
    

    /**
     * 使用StringBuilder的reverse()方法
     *
     * @param str
     * @return
     */
    private static String turnOver3(String str) 
        StringBuilder sb = new StringBuilder(str);
        return sb.reverse().toString();