判断是否回文字符串 And 最长回文字符串 子串长度

str[begin]==str[end];没有这种用法； String str 

import java.util.Scanner;  
public class Main{  
  public static void main(String[] args){  
      Scanner sc = new Scanner(System.in);   
      while(sc.hasNext()){
          String str = sc.next();
          int begin = 0;int end = str.length()-1;
          while(begin < end){
              if(str.charAt(begin)==str.charAt(end)){
                  begin++;end--;
              }
              else{
                  System.out.print("No!");
                  break;
              }
          }
          if(begin>=end){
              System.out.print("Yes!");
          }
      }
  }
}

链接：https://www.nowcoder.com/questionTerminal/df00c27320b24278b9c25f6bb1e2f3b8
来源：牛客网
import java.util.Scanner;
/**
*回文串就是一串字符正反序一样，所以将原来的字符串倒叙以后和原先字符串匹配则就是回文串
*字符串倒叙可直接用str.reverse()
*/
public class Main {
  
    public static void main(String[] args) {
            Scanner scan=new Scanner(System.in);
            while(scan.hasNext()){
            String str=scan.nextLine();               
            StringBuilder sb=new StringBuilder(str); //注意数据结构
            String newStr = sb.reverse().toString();
                
            if(str.equals(newStr)){
                System.out.println("Yes!");
            }else{
                System.out.println("No!");
            }
    }
}
}