学习到的东西: Collections.sort()对一个list排序

比较两个stringBuilder要 strb.toString().equals();

输出list 要list.get

import java.util.*;
public class Main{
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        while(scan.hasNext()){
            
            String str = scan.nextLine();
            getLength(str);
        }
        scan.close();
    }
    
    public static void getLength(String str){
        List<Integer> list = new ArrayList<>();
        for(int i = 0; i<str.length(); i++){
            for(int j = i+1; j<=str.length(); j++){
                StringBuilder strb = new StringBuilder();
                strb.append(str.substring(i,j));
                if(strb.toString().equals(strb.reverse().toString())){
                    list.add(j-i);
                }
            }
        }
//         for(int i = 0; i<list.size(); i++){
//             System.out.print(" " + list.get(i));
//         }
        Collections.sort(list);
        System.out.println(list.get(list.size()-1));
    }
}