Head First Java基础编程: 类与对象

类

1.类是定义同一类所有对象的变量和方法的蓝图或原型。
2.实例变量的值由类的每个实例提供。当创建类的实例时，就创建了这种类型的一个对象，然后系统为类定义的实例变量分配内存。然后可以调用对象的实例方法实现一些功能。
3.除了实例变量和方法，类也可以定义类变量和类方法。

类与对象

类不是对象，却是用来创建对象的模型。类会告诉虚拟机如何创建某种类型的对象。

main()的用途

1.测试真正的类
2.启动java程序

猜数字游戏

public class GuessGame {

 Player p1;
 Player p2;
 Player p3;
 
 public void startGame() {
     p1 = new Player();
     p2 = new Player();
     p3 = new Player();
     int guessp1 = 0;
     int guessp2 = 0;
     int guessp3 = 0;
     boolean p1isRight = false;
     boolean p2isRight = false;
     boolean p3isRight = false;
     int targetNumber = (int) (Math.random() * 10);
     System.out.println("I'm thinking of a number between 0 and 9...");
     while(true) {
         System.out.println("Number to guess is " + targetNumber);
         
         p1.guess();
         p2.guess();
         p3.guess();
         
         guessp1 = p1.number;
         System.out.println("Player one guessed " + guessp1);
         guessp2 = p2.number;
         System.out.println("Player two guessed " + guessp2);
         guessp3 = p3.number;
         System.out.println("Player three guessed " + guessp3);
         
         if (guessp1 == targetNumber) {
             p1isRight = true;
         }
         if (guessp2 == targetNumber) {
             p2isRight = true;
         }
         if (guessp3 == targetNumber) {
             p3isRight = true;
         }
         
         if (p1isRight || p2isRight || p3isRight)
         {
             System.out.println("We have a winner!");
             System.out.println("Player one got it right? " + p1isRight);
             System.out.println("Player two got it right? " + p2isRight);
             System.out.println("Player three got it right? " + p3isRight);
             System.out.println("Game is over");
             break;
         }
         else
         {
             System.out.println("Players will have to try again.");
         }
     }
 }
}

public class Player {
  int number = 0;
  public void guess()
  {
      number = (int) (Math.random() * 10);
      System.out.println("I'm guessing " + number);
  }
}

public class GameLauncher {
  public static void main (String[] args) {
      GuessGame game = new GuessGame();
      game.startGame();
  }
}

Java会拾荒

Java会根据对象的大小分配内存空间，对象会被存放在称为堆得内存区域中。对象被虚拟机认定为不会再被使用时，会被标记为可回收的，垃圾使其就会将其回收。

本文地址：https://blog.csdn.net/weixin_44088692/article/details/109898067