java - 当 charAt 和 String.valueOf 的值相同时，为什么它们的比较不返回 true？

Question

这是我的程序:

import java.util.Scanner;
public class Lottery
{
public static void main(String[] args)
{
    //declare and initialized variables and objects
    Scanner input = new Scanner(System.in);

    String lotteryNum = "";
    String userGuess = "";

    //Generate a 3-digit "lottery" number composed of random numbers
    int num1 = (int)(Math.random()*10);
    int num2 = (int)(Math.random()*10);
    int num3 = (int)(Math.random()*10);
    //Simulate a lottery by drawing one number at a time and 
    //concatenating it to the string
    String c1 = String.valueOf(num1);
    String c2 = String.valueOf(num2);
    String c3 = String.valueOf(num3);
    lotteryNum = (c1+c2+c3);
    //Identify the repeated steps and use a for loop structure
    //Input: Ask user to guess 3 digit number
    System.out.println("WINNER:"+lotteryNum+" Please enter your three numbers (e.g. 123): ");
    userGuess = input.next();
    System.out.println(c1.equals(userGuess.charAt(0)));
    System.out.println(userGuess.charAt(0) +"   " + userGuess.charAt(1) + "     " + userGuess.charAt(2) + "\n" + c1 + "\t"+c2+"\t"+c3);;
    if (c1.equals(userGuess.charAt(0)) && c2.equals(userGuess.charAt(1)))
        System.out.println("Winner: "+ lotteryNum+"\nCongratulations, the front pair matched.");
    else if (c2.equals(userGuess.charAt(1)) && c3.equals(userGuess.charAt(2)))
        System.out.println("Winner: "+ lotteryNum+"\nCongratulations, the end pair matched.");
    else if (c1.equals(userGuess.charAt(0)) && c2.equals(userGuess.charAt(1)) && c3.equals(userGuess.charAt(2)))
        System.out.println("Winner: "+ lotteryNum+"\nCongratulations, both pairs matched.");
    else 
                System.out.println("Winner: "+ lotteryNum+"\nSorry, no matches. You only had \n one chance out of 100 to win anyay.");

} //end main
}//end class Lottery

出于某种原因，这些行的逻辑如下:

System.out.println(c1.equals(userGuess.charAt(0)));

特别返回false，即使用户输入相同的值，即String.valueOf(num1)与userGuess.charAt(0)相同的值)，我什至将它们都视为字符串，但它仍然返回 false。这是为什么？

Answer 1

因为String不是char。

if (c1.equals(String.valueOf(userGuess.charAt(0))) 
        && c2.equals(String.valueOf(userGuess.charAt(1))))

或较短的一个

if (c1.charAt(0) == userGuess.charAt(0) && c2.charAt(0) == userGuess.charAt(1))