判断一句话中开头与结尾处字符是否相同

import java.util.Scanner;
public class TestPalindrome {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        
        
        //use the scanner function to input a sentence
        System.out.println("input a sentence");
        Scanner input = new Scanner(System.in);
        String inStr = input.nextLine();
        
        //Convert uppercase words in sentences to lowercase
        //translate the sentence into a Array
　　　　　
        String sentence=inStr.toLowerCase();将一句话中的字母全部转化为小写
        char[] elements = sentence.toCharArray(); 将这句话转化为数组的形式（也可以直接声明的一个数组将输入的句子储存进去）
        
        //read the first characters and the last characters of the sentence
        char firstChara=elements[0];
        char lastChara;
        
        
        int i=1;
        
        //make sure that the last character is a letter not others
　　　　 这一步就是从后往前读取数组中的内容，并判断是否为字符
        do {
            lastChara=elements[elements.length-i];
            i++;
        }while(!Character.isLetter(lastChara));
        
        /**
         * compare first character and last character 
         */
        if(firstChara==lastChara) {
            System.out.println("this sentence is a palindromic sentences");
        }
        else{
            System.out.println("this sentence is not a palindromic sentences");
        }
    }

}