在将列元素保持在一起的同时对二维数组进行洗牌

Question

所以我正在为一个班级做这个作业，但我一生都无法弄清楚如何使用 Collections.shuffle() 方法来洗牌由州及其首都组成的数组。现在，当我洗牌时，它会洗牌所有东西。我需要它来洗牌，但也要保持国家和首都之间的关系。 （即

[阿拉巴马][蒙哥马利],[阿拉斯加][朱诺],...

不应该变成这样的

[阿拉巴马][阿拉斯加],[朱诺][蒙哥马利],...

或

[阿拉斯加][蒙哥马利]，[朱诺][阿拉巴马]，...

有什么我遗漏的吗？这是到目前为止的工作代码...

import java.util.ArrayList; 
import java.util.Arrays; 
import java.util.Collections; 
import java.util.List; 
import java.util.Random;
/** 
* @author mstashev 
* 
* Rewrite Programming Exercise 8.37 to store the pairs of states and 
* capitals so that the questions are displayed randomly. 
* 
* Exercise 8.37 
* 
* Write a program that repeatedly prompts the user to enter a capital 
* for a state. Upon receiving the user input, the program reports 
* whether the answer is correct. Assume that 50 states and their 
* capitals are stored in a 2D array. The program prompts the user to 
* answer all state's capitals and displays the total correct count. The 
* user's answer is not case-sensitive. 
*/ 
public class RandomStateCapitalQuestionnaire {
/**
 * 
 */
public static void main(String[] args) {
    // create a 2D array storing all 50 states and capitals
    String[][] twoDStatesAndCapitals = {
            { "Alabama", "Alaska", "Arizona", "Arkansas", "California",
                    "Colorado", "Connecticut", "Delaware", "Florida",
                    "Georgia", "Hawaii", "Idaho", "Illinois", "Indiana",
                    "Iowa", "Kansas", "Kentucky", "Louisiana", "Maine",
                    "Maryland", "Massachusetts", "Michigan", "Minnesota",
                    "Mississippi", "Missouri", "Montana", "Nebraska", "Nevada",
                    "New Hampshire", "New Jersey", "New Mexico", "New York",
                    "North Carolina", "North Dakota", "Ohio", "Oklahoma",
                    "Oregon", "Pennsylvania", "Rhode Island", "South Carolina",
                    "South Dakota", "Tennessee", "Texas", "Utah", "Vermont",
                    "Virginia", "Washington", "West Virginia", "Wisconsin",
                    "Wyoming" },
            { "Montgomery", "Juneau", "Phoenix", "Little Rock", "Sacramento",
                    "Denver", "Hartford", "Dover", "Tallahassee", "Atlanta",
                    "Honolulu", "Boise", "Springfield", "Indianapolis",
                    "Des Moines", "Topeka", "Frankfort", "Baton Rouge",
                    "Augusta", "Annapolis", "Boston", "Lansing", "St. Paul",
                    "Jackson", "Jefferson City", "Helena", "Lincoln",
                    "Carson City", "Concord", "Trenton", "Santa Fe", "Albany",
                    "Raleigh", "Bismark", "Columbus", "Oklahoma City", "Salem",
                    "Harrisburg", "Providence", "Columbia", "Pierre",
                    "Nashville", "Austin", "Salt Lake City", "Montpelier",
                    "Richmond", "Olympia", "Charleston", "Madison", "Cheyenne" }            
        };//End of 2D array
    Random rnd = new Random();

    System.out.println(Arrays.deepToString(twoDStatesAndCapitals));


    List<List<String>> statesAndCapitals = twoDArrayToList(twoDStatesAndCapitals);
    Collections.shuffle(statesAndCapitals, rnd);


    System.out.println(statesAndCapitals);

    /*
     i = 0;
    for (i = 0; i < NUMBER_OF_US_STATES; i++) {
        System.out.println("Enter the Capital of the State listed: " + statesAndCapitals[i][0]);
        userInput = input.next();
        if (statesAndCapitals[i][1].equals(userInput)) {
            correctStates++;
            System.out.println("Yes that is the capital of " + statesAndCapitals[i][0] + ".");
        }//end of if

        else {
            System.out.println("No that is not the capital of " + statesAndCapitals[i][0] + ".");
            i++;
        }//end of else
    }//end of for loop

    // counts the number of correct guesses.
    System.out.println("Total number of capitals answered correctly: " + correctStates + ".");
    i++;
    return;

    */

}

public static <T> List<List<String>> twoDArrayToList(T[][] twoDArray){
    List<T> list = new ArrayList<T>();
    for (T[] array : twoDArray) {
        list.addAll(Arrays.asList(array));
    }
    return (List<List<String>>) list;
  }
}

Answer 1

这不是解决您的问题的正确数据结构。您需要一个列表/数组对（例如，List<Map.Entry<String, String>>），然后在该列表上调用 Collections.shuffle()。