Java中从类到主类的用户输入

Question

我正在尝试创建一个程序，该程序 (1) 提示输入用户的全名，然后生成用户名； (2) 提示输入一个数字，然后判断该数字是奇数还是偶数。我写了用户名和奇/偶类的代码，并想从主类中调用它们。但是，当从主类调用时，username 方法在生成用户名之前会提示用户两次，而奇/偶方法实际上并不能确定用户输入的数字是奇数还是偶数。当我从用户名类中删除扫描仪对象时，我得到一个超出范围的编译错误，所以我不得不把它放回去，这样程序才能运行。我应该使用 return 语句吗？

用户名

/**
 * Class to generate the username based on user's first name and randomly generated numbers
 */
public void username()
{
    Scanner inputReader = new Scanner(System.in);
    String fullName = inputReader.nextLine();
    // create random object and variable to store it in
    Random randomizer = new Random();
    int randomNumber = randomizer.nextInt(1000);
    // create variable to store lowercase username
    String lowercase = (fullName.toLowerCase());
    // create string variable to format username to first three characters in lowercase
    String firstThreeLetters = (lowercase.substring(0, 3));
    // concatenate lowercase characters and random number
    String usernameFinal = (firstThreeLetters + randomNumber);
    // print out final username
    System.out.println("Your username is " + usernameFinal);
}

奇/偶

/**
 * Class to determine if a user inputted value is odd or even
 */
public void OddEven1()
{
    Scanner inputReader = new Scanner(System.in);
    int userInteger = 0;
    // if/else to determine if number is odd or even
    if (userInteger % 2 == 0)
    {
        System.out.println(userInteger + " is an even number.");
    }
    else
    {
        System.out.println(userInteger + " is an odd number.");
    }
}

主要方法

{
/**
 * This class holds the main method through which all other classes are run.
 */
public static void main(String[] args)
{
    // create objects
    Username usernameGenerator = new Username();
    OddEven oddeven = new OddEven();
    Scanner inputReader = new Scanner(System.in);

    // prompt for real name and print username
    System.out.print("Name: ");
    String fullName = inputReader.nextLine();
    usernameGenerator.username();

    // prompt for number
    System.out.print("Give me a number: ");
    // variable to store value
    int userInteger = inputReader.nextInt();
    oddeven.OddEven1();
}

输出：

Answer 1

你应该像下面这样改变你的代码

main方法内部

System.out.print("Give me a number: ");
    // variable to store value
    int userInteger = inputReader.nextInt();
    oddeven.OddEven1(userInteger );

奇数/偶数

public void OddEven1(int userInteger )
{

    // if/else to determine if number is odd or even
    if (userInteger % 2 == 0)
    {
        System.out.println(userInteger + " is an even number.");
    }
    else
    {
        System.out.println(userInteger + " is an odd number.");
    }
}

现在让我们讨论一下用户名。您已经从 main 方法中捕获了用户名。所以你不需要再次从用户那里获取它。

String fullName = inputReader.nextLine();
    usernameGenerator.username(fullName );

public void username(String fullName )
{
//Your logic
}

Answer 2

1 - 你请求用户名两次，这里一次

String fullName = inputReader.nextLine();

这里有一个

Scanner inputReader = new Scanner(System.in);
String fullName = inputReader.nextLine();

我建议保留第一种方法并将fullName 传递给username() 函数。举个例子：

/**
  * Class to generate the username based on user's first name and 
   randomly generated numbers
    */
   public void username(fullName)
   {
    // create random object and variable to store it in
    Random randomizer = new Random();
    int randomNumber = randomizer.nextInt(1000);
    // create variable to store lowercase username
    String lowercase = (fullName.toLowerCase());
    // create string variable to format username to first three characters in lowercase
    String firstThreeLetters = (lowercase.substring(0, 3));
    // concatenate lowercase characters and random number
    String usernameFinal = (firstThreeLetters + randomNumber);
    // print out final username
    System.out.println("Your username is " + usernameFinal);
}

2 - 您在第二个函数 OddEven1() 中执行相同操作。我也建议将参数传递给它。例如：

public void OddEven1(number)
 {
   int userInteger = number;
   // if/else to determine if number is odd or even
    if (userInteger % 2 == 0)
     {
      System.out.println(userInteger + " is an even number.");
      }
    else
     {
       System.out.println(userInteger + " is an odd number.");
     }
 }

3 - 所以你的主要功能变成：

public static void main(String[] args)
{
// create objects
Username usernameGenerator = new Username();
OddEven oddeven = new OddEven();
Scanner inputReader = new Scanner(System.in);

// prompt for real name and print username
System.out.print("Name: ");
String fullName = inputReader.nextLine();
usernameGenerator.username(fullName);

// prompt for number
System.out.print("Give me a number: ");
// variable to store value
int userInteger = inputReader.nextInt();
oddeven.OddEven1(userInteger);
}