无法为星球大战名称生成器完成此代码

Question

我需要使用真实名字的前三个字母+真实姓氏的前两个字母，以及母亲娘家姓的前两个字母+出生城市的前三个字母。我还需要将第一个字母大写。使用 toUpperCase() 和 toLowerCase()。谢谢！

import java.util.Scanner;

public class Assignment2
{
    public static void main(String[] args) 
    {
    System.out.printf("Enter your first name: ");
    /* This should be string as your gettting name*/
    String firstname = input.nextLine(); 
    firstname = firstname.substring(0, 1).toUpperCase() + firstname.substring(1);
     /* Don't need new variable use same and that also should be string. */
    System.out.printf("Enter your last name: ");

    String lastname = input.nextLine();
    lastname = lastname.substring(0,2). toUpperCase() + lastname.substring(1);

    System.out.printf("Enter your mother's maiden name: ");
    String mothersname = input.nextLine();
    mothersname = mothersname.substring(0,2);

    System.out.printf("Enter the name of the city in which you were born: ");
    String cityname = input.nextLine();
    cityname = cityname.substring(0,3);

    String StarWarsName = firstname+lastname+mothersname+cityname;
    System.out.println("May the force be with you, " + StarWarsName );
}

  }

//* Updated code 
import java.util.Locale;
import java.util.Scanner;

public class Assignment2
{
    public static void main(String[] args) 
    {
        Scanner input = new Scanner(System.in);
        System.out.printf("Enter your first name: ");
        String firstname = input.nextLine(); 
        firstname = firstname.substring(0, 1).toUpperCase() + firstname.substring(1).toLowerCase();

    System.out.printf("Enter your last name: ");
    String lastname = input.nextLine();
    lastname = lastname.substring(0,1). toUpperCase() + lastname.substring(1).toLowerCase(); 

    System.out.printf("Enter your mother's maiden name: ");
    String mothersname = input.nextLine();
    mothersname = mothersname.substring(0,2);

    System.out.printf("Enter the name of the city in which you were born: ");
    String cityname = input.nextLine();
    cityname = cityname.substring(0,3);

    String StarWarsName = firstname+lastname+" "+mothersname+cityname;
    System.out.println("May the force be with you, " + StarWarsName );
}

  }

Answer 1

firstname cannot be resolved to a variable

您没有声明 firstname。不仅 firstname 你没有声明 lastname、mothersname、cityname。所以你应该全部申报。那些应该是 String.
您没有创建 Scanner 对象。创建 Scanner class 对象。
```
Scanner input = new Scanner(System.in);
```

下一个变化。您将 cityname 声明为两次并声明为 int 类型。但是 nextLine() returns String 不是 int.

String cityname = input.nextLine();//returns String, not int
cityname = city.substring(0,3);//returns the first 3 characters as String, not int

String#substring() returns String 不是 int。所以检查整个代码。

改变

String StarWarsName = ( "firstname"  + "lastname " + "mothersname " + "cityname");

到

   String StarWarsName = firstname+lastname+" "+mothersname+cityname;

所有这些都是变量而不是值。所以不要加双引号。

编辑：大写firstname

的第一个字母

   firstname = firstname.substring(0, 1).toUpperCase() + firstname.substring(1).toLowerCase();

Answer 2

更正了代码并在注释中解释了更改。也通过评论。不要只是复制此代码。

 import java.util.Scanner;

public class test1
{
    public static void main(String[] args) 
    {
     Scanner input = new Scanner();
    System.out.printf("Enter your first name: ");
    /* This should be string as your gettting name*/
    String firstname = input.nextLine();
     /* Don't need new variable use same and that also should be string. */
    firstname = firstname.substring(0,1);
    System.out.printf("Enter your last name: ");

    String lastname = input.nextLine();
    lastname = lastname.substring(0,2);

    System.out.printf("Enter your mother's maiden name: ");
    String mothersname = input.nextLine();
    mothersname = mothersname.substring(0,1);

    System.out.printf("Enter the name of the city in which you were born: ");
    String cityname = input.nextLine();
    cityname = cityname.substring(0,2);

    String StarWarsName = ( "firstname"  + "lastname " + "mothersname " + "cityname"); 
    System.out.println("May the force be with you, " + StarWarsName );
}

  }

无法为星球大战名称生成器完成此代码

having trouble compling this code for a starwars name generator

java

computer-science