通过 == 判断相等的字符

举例：

import java.util.*;public class Main {public static void main(String[] args) {Scanner sc = new Scanner(System.in);char ch = sc.next().charAt(0);if (ch == 'M')System.out.print("==");elseSystem.out.print("不等于");}
}

通过equals()方法检查相等的字符串

举例一：

import java.util.*;public class Main {public static void main(String[] args) {Scanner sc = new Scanner(System.in);String op = sc.next();// 将输入字符串op置于equals方法内，防止输入字符串op为空程序报错问题if ("M".equals(op))System.out.printf("==");    elseSystem.out.printf("!==");  }
}

举例二：

import java.util.Scanner;public class Main {public static void main(String[] args) {Scanner sc = new Scanner(System.in);String op = sc.next();if (op.equals("M"))System.out.print("==");elseSystem.out.print("!==");}
}