所以我正在做一个关于 Java 的 EDX 课程,我正在使用 BlueJ,但导入确实让我感到困惑。 这是其中一个模块的默认代码:
import comp102x.IO;
/**
* A class of Car objects that can move forward,backward and turn
*/
public class Car
{
private int odometer = 0; // An odometer reading initialized to 0
private String owner = "NoName"; // Name of owner
/**
* Default constructor for a Car object
*/
public Car () {}
/**
* Constructor for a Car object with a new owner’s name
* @param name name of owner
*/
public Car(String name) { // Constructor takes a name as argument
owner = name;
}
/**
* moveCar moves a car forward or backward by dist units
* @param dist Moving distance
*/
public void moveCar(int dist) {
odometer = odometer + Math.abs(dist);
IO.outputln(owner + "'s car has moved " + dist + " units.");
}
/**
* turnCar turns a car by a given degree
* @param angle Turn angle in degrees
*/
public void turnCar(double angle) {
IO.outputln(owner + "'s car has turned " + angle + " degrees.");
}
/**
* getOdometer gets the odometer reading of a car
* @return The value of odometer
*/
public int getOdometer() {
return odometer;
}
我很困惑为什么 import java.io.* 不起作用,因为这是用于从 IO 包导入类的默认设置,对吗?但是代码没有编译,它说“未声明的变量:IO”,我不明白为什么。就像包必须保存在您的笔记本电脑上一样,它们实际上是从哪里导入的?当我在 google 中输入 import comp102x.IO 时,什么也没有出现,我在哪里可以找到这个包?当您要使用导入包或某些类时,我们是否必须将其保存在我们的计算机上才能使用它以及我们在哪里找到它?
抱歉问了这么多问题,我只是对导入感到很困惑。