数组中的最后一个对象替换所有其他对象

Question

当我创建这个数组时，我创建的最后一个对象替换了之前的两个对象。

public class Main
{
   public static final int NUM_CARS = 3;
   private static Scanner scanner;
   
   public static void main(String[] args)
   {
      Car[] cars;
      cars = new Car[NUM_CARS];
      cars[0] = new Car( "Toyota Camry", 3400 );
      cars[1] = new Car( "Ford F-150", 5000 );
      cars[2] = new Car( "Honda Civic", 3000 );
      System.out.println( cars[0] );
      System.out.println( cars[1] );
      System.out.println( cars[2] );

这应该打印每辆汽车的品牌和型号及其 MPG。但它最终打印了第三个对象（Civic）三次。这是构造函数：

public class Car
{
   private static String model; // Car make and model (e.g. "BMW 328i)
   private static double mpg; // Car's miles per gallon
   private static double milesDriven; // The total miles driven (odometer)
   private static double fuelGallons; // The amount of fuel in the tank (in gallons)
   
   public Car( String carModel, int weight )
   {
      model = carModel;
      if ( weight > 4000 )
         mpg = 20.0;
      else
         mpg = 30.0;
      milesDriven = 7;
      fuelGallons = 15;
   }

我认为 "new" 不会覆盖数组中的每个元素，但事实并非如此。

Answer 1

提示：忘记 static 关键字，它不好

Answer 2

您 Car class 中的所有字段都声明为静态的。这意味着这 4 个字段由所有 Car 个实例共享。

将 Car class 的开头替换为：

public class Car
{
   private String model; // Car make and model (e.g. "BMW 328i)
   private double mpg; // Car's miles per gallon
   private double milesDriven; // The total miles driven (odometer)
   private double fuelGallons; // The amount of fuel in the tank (in gallons)

解决您的问题。

数组中的最后一个对象替换所有其他对象

Last Object in Array Replacing All Other Objects

java

arrays

new-operator