【面试】将字符串倒序输出

1：递归

public static void main(String[] args) {

        String  s="abcdefg";
        dgTest(s);
        StringBuilder b = new StringBuilder(s);
        System.out.print(b.reverse().toString());
}


public static String dgTest(String s) {
    if(s == null || s.length() <= 1) {
        return s;
    }else{
        return dgTest(s.substring(1)) + s.charAt(0);

    }
}

 

2：使用StringBuild 和 StringBuffer的reverse()

StringBuilder stringBuilder = new StringBuilder();
stringBuilder.append("abcdefg");
System.out.println(stringBuilder.reverse()); 

StringBuffer stringBuffer = new StringBuffer();
stringBuffer.append("abcdefg");
System.out.println(stringBuffer.reverse());

 

3：数组循环

public static void main(String[] args) {

        String s = "12345678";

        char[] array = s.toCharArray();  //转成char数组

        for (int i = 0; i < s.length() / 2; i++) {

            array[i] = s.charAt(s.length() - 1 - i);

            array[s.length() - 1 - i] = s.charAt(i);

            System.out.println(array);
        }

    }