变换二维数组，同时保持列元素在一起

Question

所以我正在为一个类做这个作业，我不能为我的生活弄清楚如何使用Collections.shuffle()方法来洗牌一个由州及其首府组成的数组。现在当我洗牌数组时，它洗牌了所有的东西。我需要它来洗牌一切，但也要保持国家和资本之间的关系。(即

(阿拉巴马州)(Montgomery),(阿拉斯加)(朱诺)……

不应该变成这样

(阿拉巴马州)(阿拉斯加),朱诺(Montgomery),…

或

(阿拉斯加)[蒙哥马利],[朱诺][阿拉巴马州],…

我是不是漏掉了什么?下面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

这不是适合您的问题的数据结构。您需要一个对的列表/数组(例如，List<Map.Entry<String, String>>)，并调用该列表上的Collections.shuffle()。