java类与对象，用程序解释

//第一个 1 public class Cardemo{
 2     public static void main(String[] args){
 3         Car carwind = new Car(60,"red","west");
 4         carwind.speed = 60;
 5         carwind.color = "red";
 6         carwind.direction = "west";
 7
 8         System.out.println("The speed of car is " + carwind.speed);
 9         System.out.println("The color of car is " + carwind.color);
10         System.out.println("The direction of car is " + carwind.direction);
11     }
12 }
13 class Car{
14     //定义四个成员变量（属性）
15     int speed;
16     String color;
17     String name;
18     String direction;
19 }

第二个

public class Cardemo{
    public static void main(String[] args){
        Car carwind = new Car(60,"red","west"); //创建一个Car类的引用
        carwind.speed = 60;
        carwind.color = "red";
        carwind.direction = "west";

        System.out.println("The speed of car is " + carwind.speed);
        System.out.println("The color of car is " + carwind.color);
        System.out.println("The direction of car is " + carwind.direction);
        carwind.drivecar();
        carwind.speedup(5);
        System.out.println("The speed of car is " + carwind.speed);

    }
}
class Car{
    //定义四个成员变量（属性）
    int speed;
    String color;
    String name;
    String direction;

    Car(int speed, String color, String direction){
        this.speed = speed;
        this.color = color;
        this.direction = direction;
    }

    public void drivecar(){
        System.out.println("here we go!");
    }
    public void speedup(int aspeed){
        this.speed = speed + aspeed;
    }
}