java - 数组和方法 addcar

Question

我正在准备考试，在对其中一种方法进行编程时遇到问题它是一个 addcar 方法，我不知道如何处理这个方法。

addcar 的说明:该方法将向列表中添加一辆汽车，但首先需要检查 id 是否尚未输入添加。如果 id 已经在数组中，您应该打印“无法添加这辆车，因为该 ID 已在列表中”。如果不可能的话由于数组已满而添加汽车，您应该打印一条错误消息“添加列表已满时出错”。

代码如下，从Car类开始到CarDealer类(其中应添加addcar方法)。 addcar 方法中的条件应该是正确的，但我不知道如何使用参数中的变量。

<div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
<div class="snippet-code">
<pre class="snippet-code-js lang-js prettyprint-override"><code>    public class Car {
        private int id;
        private String model;
        private int year;
        private double price;
        public Car() {
        	id = 0;
        	model = null;
        	year = 0;
        	price = 0;
        }
        public Car(int id, String model, int year, double price) {
             this.id = id;
             this.model = model;
             this.year = year;
             this.price = price;
        }
    	public int getId() {
    		return id;
    	}
    	public void setId(int id) {
    		this.id = id;
    	}
    	public String getModel() {
    		return model;
    	}
    	public void setModel(String model) {
    		this.model = model;
    	}
    	public int getYear() {
    		return year;
    	}
    	public void setYear(int year) {
    		this.year = year;
    	}
    	public double getPrice() {
    		return price;
    	}
    	public void setPrice(double price) {
    		this.price = price;
    	}
    }
    public class CarDealer {
        private Car[] Cars;
        private int nCars;
        public final static int MAXSIZE = 100;``

        public CarDealer() {
        	Cars = new Car[MAXSIZE];
        	nCars = 0;
        }
        public int getnCars() {
        	return nCars;
        }
        public int findcar(int id) {
        
        for(int i = 0; i<nCars; i++) {
        	if(id == Cars[i].getId()) {
        		return i;
        	}
        }
        return -1;
        }
        public void addCars(int id, String model, int year, double price) {
        	if(nCars < MAXSIZE) {
        	for(int i = 0; i<nCars; i++) {
            	if(id == Cars[i].getId()) {
            		System.out.println("The car is already added");
            	}
        }}
        	else 
        		System.out.println("ERROR: ADDING LIST IS FULL");
        }}</code></pre>
</div>
</div>

Answer 1

这是逻辑，请通过评论来理解

public void addCars(int id, String model, int year, double price) {
    if(nCars < MAXSIZE) { // check if the number of cars is less than MaxSize to add
        for(int i = 0; i<MAXSIZE; i++) { // go through the all the cars in the list
            if(Cars[i] != null) { // check if the car in this index is not empty
                if(id == Cars[i].getId()) { // check the id of the car is the same in the list
                    System.out.println("The car is already added"); // print already added if so
                    break; // break since you found a duplicate (an existing car id)
                }
            }else { // you come to this logic because the Car object in the index (i) is empty which means there is no car added
                   // since you add car sequentially in the car list then its safe 
                Car carObj = new Car(id, model, year, price);
                Cars[i] = carObj; // set the car object
                nCars++;  // increment the current car size 
                System.out.println("Added");
                break; // break since you have added the car to the list and no need to go through the for loop
            }
        }
    }
    else 
        System.out.println("ERROR: ADDING LIST IS FULL");
}