我有一个通过以下方式完成的名为Item的类
public class Item {
private static int nextId = 0;
private double xCoord, yCoord; //location
private double length, height; // define size of item
private String spriteImage;
private Tank tank;
private String id;
protected Item(double xCoord, double yCoord, String spriteImage, double length, double height, Tank tank) throws ItemException {
setId("I"+nextId);
nextId++;
setLocation(xCoord,yCoord);
setSpriteImage(spriteImage);
setLength(length);
setHeight(height);
setTank(tank);
}
/**
* Set this item's location.
*
* @param xCoord the column coordinate.
* @param yCoord the row coordinate.
*/
public void setLocation(double xCoord, double yCoord) {
this.xCoord = xCoord;
this.yCoord = yCoord;
}
public double getXCoord() {
return xCoord;
}
public double getYCoord() {
return yCoord;
}
public double getLength() {
return length;
}
public void setLength(double length) throws ItemException{
if(length<=0) {
throw new ItemException("MSG_ERR_LENGTH_VALUE");
}
this.length = length;
}
public double getHeight() {
return height;
}
public void setHeight(double height) throws ItemException{
if(height<=0) {
throw new ItemException("MSG_ERR_HEIGHT_VALUE");
}
this.height = height;
}
public void setSpriteImage(String spriteImage) {
this.spriteImage = spriteImage;
}
public String getSpriteImage() {
return spriteImage;
}
public String getId() {
return id;
}
protected void setId(String id) {
this.id = id;
}
public Tank getTank() {
return tank;
}
public void setTank(Tank tank){
if(tank!=null) {
if(!tank.getItems().contains(this)) {
tank.getItems().add(this);
}
}
if(this.tank!=null) {
try{
this.tank.removeItem(this);
}catch(Exception e) {
//removeItem: El item no existe ya en el tanque
}
}
this.tank = tank;
}
@Override
public String toString() {
StringBuilder str = new StringBuilder("(" + getXCoord() +", "+ getYCoord() +") ");
str.append(getId() + " ");
str.append(getLength() + " ");
str.append(getHeight() + " ");
str.append((getTank()!=null)?getTank().getName():"No tank");
return str.toString();
}
}
我的问题是我必须实现两个类,其中一个是从Items继承的,他们问我:这个类只有一个构造函数,它将与参数。这些的顺序为:xCoord,yCoord,长度,高度,能量和坦克。 spriteImage的值将始终为相同:“ ./ images / food / seed.png”我将其实现如下
public class Food extends Item {
double speed=1;
boolean eaten;
int energy;
protected Food(double xCoord, double yCoord, String spriteImage, double length, double height,int energy, Tank tank)
throws Exception {
super(xCoord, yCoord, spriteImage, length, height, tank);
setSpeed(speed);
setEnergy(energy);
setSpriteImage("./images/food/seed.png");
}
另一个类是相同的,他们问我这个类将只有一个构造函数,并且将参数的顺序为:xCoord,yCoord,长度,高度和水箱。 spriteImage的值将始终为相同:“ ./ images / submarine / submarine.png”
public class SubmarineToys extends Item{
double speed=1;
boolean facingRight=true;
double thresholdReverse=0.0003;
protected SubmarineToys(double xCoord, double yCoord, String spriteImage, double length, double height, Tank tank)
throws ItemException {
super(xCoord, yCoord, spriteImage, length, height, tank);
setSpriteImage("./images/submarine/submarine.png");
}
我的问题是,我无法在两个类中都要求我的构造函数仅具有告诉我的参数。
构造函数,取决于超类,总是在Super()中为我创建Item的参数,但是他们要求我仅提供他们要求的参数,这意味着从构造函数中删除“ spriteImage”超类的。
某种方式?
项目类别不是抽象的吗?
您可以简单地从儿童的ctor中省略spriteImage。结果应该是这样的:
public class Food extends Item {
private static String foodSpriteImage = "./images/food/seed.png";
private double speed=1;
private boolean eaten;
private int energy;
protected Food(double xCoord,
double yCoord,
double length,
double height,
int energy,
Tank tank)
throws Exception {
super(xCoord, yCoord, spriteImage, length, height, tank);
setEnergy(energy);
}
}