//方法一
String originalString = "abcdefg";
StringBuffer stringBuffer = new StringBuffer(originalString);
System.out.println(stringBuffer.reverse());


//方法二
String originalString = "abcdefg";
String resultString = "";
char[] charArray = originalString.toCharArray();
for (int i = charArray.length-1; i>=0; i--){
        resultString +=charArray;
   }
        System.out.println(resultString);
}

//方法一
String originalString = "abcdefg";
StringBuffer stringBuffer = new StringBuffer(originalString);
System.out.println(stringBuffer.reverse());


//方法二
String originalString = "abcdefg";
String resultString = "";
char[] charArray = originalString.toCharArray();
for (int i = charArray.length-1; i>=0; i--){
        resultString +=charArray;
   }
        System.out.println(resultString);
}