java - 为什么这不仅会返回回文字符串？

Question

下面是我编写的代码，目的是让用户输入几个不同的字符串，检查每个字符串是否是回文，然后仅返回回文。目前，所有输入的字符串都将被返回。看来 IF 语句 if 不能正常工作。关于如何返回正确的字符串有什么建议吗？

import java.util.Scanner;

public class hh {

static void checkPalin ()   {
// creates a scanner
Scanner input = new Scanner(System.in);
int i = 0; 
String userInput = "";

// asks the user for the number of strings 
System.out.print("Enter the number of strings: ");

StringBuilder sentence = new StringBuilder(userInput);

StringBuilder palindrome = new StringBuilder();

// stores the number of strings user will enters
int stringNumber = input.nextInt();

// prompts the user to enter in their sentences 
System.out.println("Enter the strings:");

// this loop will go until the number of strings entered are entered
while(i <= stringNumber){

    userInput = input.nextLine();
    if(sentence.reverse().equals(sentence)){
    palindrome.insert(0, " " + userInput);
    }
        i ++;
}
// if( sentence == sentence.reverse()){
System.out.println("The palindromes are: " + palindrome);
}


public static void main(String[] args)  { 

    checkPalin();
}
}

Answer 1

您需要创建 String来自StringBuilder使用toString调用equals之前的方法:

if(new StringBuilder(userInput).reverse().toString().equals(userInput)) { ... }