public static void main(String[] args) {
Scanner input=new Scanner(System.in);
String uname,pwd;
System.out.println("请输入用户名:");
uname=input.next();
System.out.println("请输入密码:");
pwd=input.next();
if(uname.equals("Tom")&&pwd.equals("1234567")){
System.out.println("登录成功！");
}else{
System.out.println("用户名或密码不匹配！");
}

}

字符串的比较