程序沒有讀取來自URL的輸入

Question

所以我的程序應該從URL讀取一個名稱列表，以玩猜名遊戲;但是，該程序似乎無法讀取URL中的任何內容，更不用說將其添加到ArrayList中。運行該程序時，我所得到的是「此列表中有0個名稱」，表示沒有從該URL添加名稱。

當我使用調試器並進入URL時，出現錯誤提示「無法執行，選定的線程未掛起」。

import java.io.IOException; 
import java.net.MalformedURLException; 
import java.net.URL; 
import java.util.ArrayList; 
import java.util.Collections; 
import java.util.Scanner; 

public class NameGuesser { 
    private ArrayList<String> lastNames = new ArrayList<String>(); 
Scanner input = new Scanner(System.in); 
    public void readNames() throws IOException, MalformedURLException { 
     // Read the last names 

     URL url = new URL(
       "http://www2.census.gov/topics/genealogy/1990surnames/dist.all.last"); 

     Scanner in = new Scanner(url.openStream()); 
     while (in.hasNext()) { 
      // Read the last name 
      String lastName = in.next(); 
      lastNames.add(lastName); 

      // Ignore the statistical information 
     // in.nextDouble(); 
      // in.nextDouble(); 
     // in.nextInt(); 
     } 
     in.close(); 

     // Print out the number of names in the file and 
     // Sort the names using Collections 
     Collections.sort(lastNames); 
     System.out.println("There are " + lastNames.size() + " names in this list"); 
    } 

    public int guessName() { 
     int counter = 0; 
     int low = 0; 
     int high = lastNames.size(); 
     int mid = high/2; 
     boolean notFound = true; //variables to hold game info 
     String userInput = ""; 
     while (notFound) { //while the name is not found 
      System.out.println("Does your name come before " + lastNames.get(mid) + " in the dictionary? (Y/N), or is " + lastNames.get(mid) + " your name? (S)"); 
      userInput = input.next(); //ask if it is in the middle 
      if (userInput.equalsIgnoreCase("Y")) { //if before, set new upper bound 
       high = mid; 
       mid = ((high - low)/2) + low; 
       counter++; 
      } else if(userInput.equalsIgnoreCase("N")){ //if after, set new lower bound 
       counter++; 
       low = mid; 
       mid = ((high - low)/2) + low; 
      } 
      else{ //if name is found, return counter 
       System.out.println("Your name, " + lastNames.get(mid) + ", was found with " + counter + " guesses."); 
       input.close(); 
       return counter; 
      } 
      if(high == low){ //if upper and lower bounds are equal 
       System.out.println("Is your name: " + lastNames.get(mid) + " ? (Y/N)"); 
       userInput = input.next(); //ask if name is found 
       if(userInput.equalsIgnoreCase("Y")){ //if yes, print success, counter, and return counter 
        System.out.println("Your name, " + lastNames.get(mid) + ", was found with " + counter + " guesses."); 
        input.close(); 
        return counter; 
       } 
       else if(userInput.equalsIgnoreCase("N")){ //if no, inform user that guesser failed 
        System.out.println("Name not found. Attempted locating with " + counter + " guesses"); 
        input.close(); 
        return counter; 
       } 
      } 
     } 
     input.close(); 
     return counter; 
    } 
} 

測試方法：

import java.io.IOException; 
import java.net.MalformedURLException; 


    public class NameGame { 

     public static void main(String[] args) throws MalformedURLException, IOException { 
      NameGuesser game = new NameGuesser(); 

      game.readNames(); 
     } 
    } 

Answer 1

你試過在瀏覽器中打開URL？它重定向到一個安全協議（HTTPS）。 將您的網址更改爲「https://www2.census.gov/topics/genealogy/1990surnames/dist.all.last」，它應該可以正常工作。