Question

对于ArrayLists，我是初学者，所以我很困惑如何将2D数组转换为ArrayList。我目前正在编写一个保留剧院座位的程序，但我正在使用2D阵列用于行和行中的座位，但我想使用ArrayList而不是2D阵列。每当我尝试搜索它时，我都找不到任何其他内容。我还有另外两个类，它们是用于销售和预订票证的getter和setter，以及一个用于菜单和switch语句的主类。谢谢！

import java.util.Scanner;

/**

*/
public class Theatre {

//Number of rows in the theatre
public static final int NUMBER_ROWS = 10;
//Number of seats that are in each row
public static final int NUMBER_OF_SEATS_IN_ROW = 15;
private Seat[][] seat = new Seat[NUMBER_ROWS][NUMBER_OF_SEATS_IN_ROW];

public Theatre(){
    for(int x=0;x<seat.length;x++){
        for(int y=0;y<seat[x].length;y++){
            seat[x][y] = new Seat();

            if(x<5){ // If row is less than 5, set price of seat to 100
                seat[x][y].setPrice(100);
            }else{ // If row is not less than 5, set price to 70
                seat[x][y].setPrice(70);
            }
        }
    }
}


/**
 * This method prompts for row and seat number and reserves it under a name if it is not already reserved
 */
public void reserveSeat(){
    Scanner input = new Scanner(System.in);
    int row;
    int seat;
    //Gathering row number with validation
    do{
        System.out.print("Please select row: ");
        row = input.nextInt();
        row--;
    }while(row<0||row>=NUMBER_ROWS);
    //Gathering seat number with validation
    do{
        System.out.print("Please select seat: ");
        seat = input.nextInt();
        seat--;
    }while(seat<0||seat>=NUMBER_OF_SEATS_IN_ROW);
    if(row<5){
        System.out.println("Price: $100");
    }else{
        System.out.println("Price: $70");
    }

    if(this.seat[row][seat].isSold()){ // If seat is reserved, display message
        System.out.println("This seat is reserved");
    }else{ // If seat is not reserved, prompt for name and reserve it

        System.out.print("Please enter your name to reserve seat: ");
        this.seat[row][seat].setReservedBy(input.next());
        this.seat[row][seat].setSold(true);
    }
}
/**
 * This method displays all the seats and gives a visual representation of which seats are reserved
 */
public void showReservations(){
    String output = "";
    for(int x=0;x<seat.length;x++){
        for(int y=0;y<seat[x].length;y++){
            if(seat[x][y].isSold()){ // If seat is sold, append "x"
                output += "x ";
            }else{ // If seat is not sold, append "o"
                output += "o ";
            }
        }
        output += "Row "+(x+1)+"\n"; // Append newline character when row is complete
    }
    System.out.println(output);
}

/**
 * This method calculates the total value of seats sold and displays it
 */
public void showTotalValue(){
    double totalValue = 0;
    for(int x=0;x<seat.length;x++){
        for(int y=0;y<seat[x].length;y++){
            if(seat[x][y].isSold()){ // If seat is sold, add price of seat to totalValue
                totalValue += seat[x][y].getPrice();
            }
        }
    }
    System.out.println("The total value of seats sold is $"+totalValue);
}

}

Answer 1

您可以像这样创建ArrayList<ArrayList<Seat>>：

public class Theatre {
    //Number of rows in the theatre
    public static final int NUMBER_ROWS = 10;
    //Number of seats that are in each row
    public static final int NUMBER_OF_SEATS_IN_ROW = 15;
    // Passing NUMBER_ROWS to the constructor sets aside that much space
    // but the array is still empty.
    private ArrayList<ArrayList<Seat>> seat = new ArrayList<ArrayList<Seat>>(NUMBER_ROWS);

    public Theatre(){
        for(int x=0; x NUMBER_ROWS; x++){
            seat.add(new ArrayList<Seat>(NUM_OF_SEATS_IN_ROW);
            for(int y=0; y < NUMBER_OF_SEATS_IN_ROW; y++){
                seat.get(x).add(new Seat());
                // etc.
            }
         }
    }
}

Answer 2

您可能希望构建一个列表列表，如下所示：

List<List<Seat>> seats = new ArrayList<List<Seat>>();

然后您可以添加更多行：

seats.add(new ArrayList<Seat>);

并获得座位对象：

seats.get(row).get(column);

您也可以在此处找到更多信息：2 dimensional array list

如何在Java中将2D数组更改为ArrayList

2 个答案: