CompareTo和If语句

Question

我是一个Java初学者。现在，我尝试修复代码中的错误。据说有3个错误：else without if。我一直在改变我的代码，但看起来我会有更多的其他错误。

我编写了一个程序，询问用户的姓氏，询问他们在点名过程中必须等待多长时间，并且我需要使用else if来使只打印一条语句。

import java.util.Scanner;
public class CompareTo
{public static void main( String[] args )
    {   Scanner Keyboard = new Scanner (System.in);

        String Name, Carswell, Jones, Smith, Young;
        System.print.out( "What's your last name? ");
        Name = Keyboard.next();   
        "Name".compareTo("Carswell");

        if ( "Name" < "Carswell" )
        {System.out.print( "You dont' have to wait long, " + Name);
        }

        "Name".compareTo("Jones"); 
         else if ( "Name" > "Carswell"  && Name < "Jones" )
        {System.out.print( "that's not bad, "  + Name );
        }

        "Name".compareTo("Smith");
        else if ( "Name" > "Jones" && Name < "Smith")
        {System.out.print( "looks like a bit of a wait, "  + Name );
        }

        "Young".compareTo("Young");
         else if ( "Name" > "Smith" && Name < "Young" )
        {System.out.print( "it's gonna be a while, "  + Name );
        }

        else 
        {System.out.print( "not going anywhere for a while, "  + Name );
        }
    }
}

Answer 1

问题出在这里：

if ( "Name" < "Carswell" )
{System.out.print( "You dont' have to wait long, " + Name);
}

"Name".compareTo("Jones"); //This is the issue
 else if ( "Name" > "Carswell"  && Name < "Jones" )
{System.out.print( "that's not bad, "  + Name );
}

if和else if之间有"Name".compareTo("Jones");。if和else if之间不应该有任何代码。将上面的代码移动到if块或else if块以编译您的代码。

Answer 2

您的代码有很多错误，但正如您所说的，您得到的是else，如果没有if，那么请考虑以下内容

import java.util.Scanner;

类CompareTo{

public static void main(String[] args){
    Scanner keyboard = new Scanner(System.in);

    String Name, Carswell, Jones, Smith, Young;

    System.out.println( "What's your last name? ");

    Name = keyboard.next();   

    if ( Name.compareTo("Carswell")<0 )
    {
        System.out.print( "You dont' have to wait long, " + Name);
    }

    /*
        if you have an else if after if; then between them
        you cannot write any other code 
        because you cant write an else if without an if 
        thats why you getting error
    */

    else if(Name.compareTo("Carswell") > 0 && Name.compareTo("Jones")<0){
        System.out.print( "that's not bad, "  + Name );
    }
}

}

Answer 3

//千万不要使用java预定义的方法作为类名

//变量必须以小写字母开头

public class TestClass{
public static void main( String[] args ) 
{ 
    Scanner Keyboard = new Scanner (System.in);
    String Name, Carswell, Jones, Smith, Young;
    System.out.print( "What's your last name? ");
    Name = Keyboard.next();
    if (Name.compareTo("Carswell")<0){
        System.out.print( "You dont' have to wait long, " + Name);
    }
    //You need to use || not &&
    else if (Name.compareTo("Carswell")>0  || Name.compareTo("Jones")<0 ) {
        System.out.print( "that's not bad, "  + Name );
    }
    else if (Name.compareTo("Jones")>0 || Name.compareTo("Smith")<0)
    {
        System.out.print( "looks like a bit of a wait, "  + Name );
    }

    else if ( Name.compareTo("Smith")>0 || Name.compareTo("Young")<0){
        System.out.print( "it's gonna be a while, "  + Name );
    }

    else {
        System.out.print( "not going anywhere for a while, "  + Name );
    }
}
}