java - 显示用户输入的第一个字母

Question

例如，我有一个随机的用户输入列表。用户输入的范围可以是 1-10。然后，用户输入将入队并出队以显示用户输入列表。

但是，我想使用用户输入来显示每个用户输入的第一个字母。我尝试创建一个名为 name1 的新变量来存储用户输入，但由于 name1 变量为空，它返回错误。

for(int i =1;i<=value ;i++){
    System.out.println("Enter name #" + i+":");
    String name = input.next();
    String name1 = name;
    myQueue.enqueue(name);   
 }
System.out.println("List of names: ");
for(int j=1; j <=value; j++){
    System.out.println(j+". " +(myQueue.dequeue()));

} 
System.out.println("Statistics:");
char firstletter = name1.charAt(0); //error: value is null 
System.out.println(firstletter); 

Answer 1

希望这对您有帮助

import java.util.LinkedList;
import java.util.Scanner;

class GenQueue<E> {
   private LinkedList<E> list = new LinkedList<E>();
   public void enqueue(E item) {
      list.addLast(item);
   }
   public E dequeue() {
      return list.poll();
   }
   public boolean hasItems() {
      return !list.isEmpty();
   }
   public int size() {
      return list.size();
   }
   public void addItems(GenQueue<? extends E> q) {
      while (q.hasItems())
         list.addLast(q.dequeue());
   }
}

public class myQueue {
   public static void main(String[] args) {
      GenQueue<Employee> empList;
      empList = new GenQueue<Employee>();
      GenQueue<HourlyEmployee> hList;
      hList = new GenQueue<HourlyEmployee>();

      Scanner reader = new Scanner(System.in);  // Reading from System.in
      System.out.println("Enter a number: ");
      int n = reader.nextInt(); // Scans the next token of the input as an int.
      for(int i =1;i<=n ;i++){
          System.out.println("Enter a name: ");
          String name = reader.next();

          hList.enqueue(new HourlyEmployee(name, name));
          empList.addItems(hList);
      }
      System.out.println("The employees' names are:");
      while (empList.hasItems()) {
         Employee emp = empList.dequeue();
         //System.out.println(emp.firstName + " "  + emp.lastName);
         char firstletter = emp.firstName.charAt(1); //error: value is null 
         System.out.println(firstletter); 
      }
   }
}

class Employee {
   public String lastName;
   public String firstName;
   public Employee() {
   }
   public Employee(String last, String first) {
      this.lastName = last;
      this.firstName = first;
   }
   public String toString() {
      return firstName + " " + lastName;
   }
}

class HourlyEmployee extends Employee {
   public double hourlyRate;
   public HourlyEmployee(String last, String first) {
      super(last, first);
   }
}