java - 从 ArrayList 到 Hashmap

Question

我是 Java 新手，正在尝试使用下面的工作代码并将我的 ArrayList 转换为 Hashmap。我感到困惑，因为它们根本不同。由于 HashMap 使用键/值对，我不太明白，鉴于我已经在工作的程序，我会这样做。抱歉，如果这是一个愚蠢的问题，我想我对我需要做什么感到困惑。

这是我使用 ArrayList 的类:

感谢您的帮助。

import java.util.ArrayList;
import java.util.Scanner;

//new class ArrayMessage
public class ArrayMessage {

//new method shoutOutCannedMethod returning a String
public String shoutOutCannedMessage() {

    // create some variables
    int arraySize = 10;
    String displayUserMessage = "";
    String userMessage = "";
    String goAgain = "yes";

    // setup scanner to store input
    Scanner input = new Scanner(System.in);

    // create arrayList
    ArrayList<String> message = new ArrayList<String>();

    // start loop
    while (!goAgain.equals("no")) {
        // clear out arrayList
        message.clear();

        // ask the user for 10 messages as long as the counter is less than
        // the size of the array
        for (int counter = 0; counter < arraySize; counter++) {
            System.out.printf(counter + 1 + ": Please enter a message: ");
            // save user message to userMessage
            userMessage = input.nextLine();
            // add users message to arraylist
            message.add(userMessage);

        }

        // ask the user if they want to to load different messages into
        // arraylist
        System.out.print("Messages have been loaded? Would you like to reload? Type 'yes' or 'no': ");
        goAgain = input.nextLine(); // store input
    }
    // ask the user to choose which message they want displayed
    System.out.print("Please enter the number of the message you would like displayed: ");
    userMessage = input.nextLine();
    // store users message into variable to be used later
    displayUserMessage = message.get(Integer.parseInt(userMessage) - 1);

    input.close();
    // return userMessage
    return displayUserMessage;

}

}

这是我的主课:

public class ShoutBox {

//main method
public static void main(String[] args) {

    //call ArrayMessage class 
    ArrayMessage myMessage = new ArrayMessage();
    //call shoutOutCannedMessage method 
    String userMessage = myMessage.shoutOutCannedMessage();
    // display message selected by user
    System.out.printf("Your selected value is " + userMessage + "\n");


}

}

Answer 1

我假设您将使用 ArrayList 中元素的索引作为键，并将数组中的实际元素作为 HashMap 中的值。

希望有帮助!