toString方法用Java调用

Question

可能重复:
为什么在打印对象时调用toString()方法？

我在下面有这段代码.我使用Room Class中的toString方法了解除输出之外的所有其他内容.在HotelMain Class中,我刚刚调用了酒店类中的displayRooms方法.但是,当我运行程序时,控制台中显示了toString输出.

如果我正确toString()是对象中值的文本表示.但是,我不确定我在哪里调用toString方法.

有人可以解决我的困境吗？谢谢.

酒店等级

public class Hotel {

private String hotelName;
private Room[] rooms;

public Hotel(String hotelName, int numberOfRooms) {
    this.hotelName = hotelName;
    this.rooms = new Room[numberOfRooms];
}

public void addRooms(Room room) {

    int position = -1;

    for (int i = 0; i < this.rooms.length; i++) {
        Room tempRoom = rooms[i];

        if (tempRoom == null) {
            position = i;
            break;
        }
    }

    if (position != -1) {
        rooms[position] = room;
        System.out.println("New room added at postion " + position);

    } else {
        System.out.println("Addition of room failed.");
    }
}

public void displayRooms() {

    System.out.println("The Hotel: " + this.hotelName + " has the following rooms.");

    for (int i = 0; i < this.rooms.length; i++) {
        Room tempRoom = rooms[i];
        if (tempRoom != null) {
            System.out.println(tempRoom);
        }
    }

}

房间等级

public class Room {

private int roomNumber;
private int numberOfBeds;
private boolean smokingOrNonSmoking;

public Room() {

}

public Room(int roomNumber, int numberOfBeds, boolean smokingOrNonSmoking) {
    this.roomNumber = roomNumber;
    this.numberOfBeds = numberOfBeds;
    this.smokingOrNonSmoking = smokingOrNonSmoking;
}

@Override
public String toString() {
    return "Room [roomNumber=" + roomNumber + ", numberOfBeds="
            + numberOfBeds + ", smokingOrNonSmoking=" + smokingOrNonSmoking
            + "]";
}

}

酒店主要

public class HotelMain {

public static void main(String[] args) {

Hotel hotel = new Hotel("MahaRani Chain of Hotels", 10);
Room room1 = new Room(4, 2, true);
Room room2 = new Room(2, 1, false);
Room room3 = new Room(6, 3, true);
Room room4 = new Room(6, 4, false);

hotel.addRooms(room1);
hotel.addRooms(room3);
hotel.addRooms(room4);
hotel.addRooms(room2);

hotel.displayRooms();

}

}

安慰

Answer 1

Room tempRoom = rooms[i];
if (tempRoom != null) {
    System.out.println(tempRoom);
}

您的方法中包含上述代码displayRooms().它打印tempRoom,这是一个参考Room,因此它调用toString()在Room类中重写的方法.

Answer 2

你打电话的时候

System.out.println(tempRoom);

toString()Room 的方法被自动调用tempRoom.

Answer 3

在这一行

System.out.println(tempRoom);

这是一样的

 System.out.println(tempRoom.toString());