public class C {
  public static void main(String[] args){

    Child ch1 = new Child(12,"小小");
    ch1.joinGame();
    Child ch2 = new Child(13,"小紅");
    ch2.joinGame();
    //調(diào)用類變量
    System.out.println("一共有" + Child.total+ "小朋友");
  }
}

class Child{
  public int age;
  public String name;

  //total是靜態(tài)變量,因此他可以被任何類調(diào)用
  public static int total = 0;

  public Child(int age, String name)
  {
    this.age = age;
    this.name = name;
  }

  public void joinGame()
  {
    total++;
    System.out.println("有一個(gè)小朋友加進(jìn)來！");
  }
}

public class C {

  static int i = 1;
  static
  {
    System.out.println("靜態(tài)區(qū)域塊被執(zhí)行一次");
    //該靜態(tài)區(qū)域塊,只被執(zhí)行一次，也不會(huì)因創(chuàng)建對(duì)象而觸發(fā)
    i++;
  }
  public C()
  {
    System.out.println("構(gòu)造函數(shù)域塊被執(zhí)行一次");
    i++;
  }

  public static void main(String[] args){

    C t1 = new C();
    System.out.println("輸出第一個(gè)i的值為：" + C.i);
    C t2 = new C();
    System.out.println("輸出第二個(gè)i的值為：" + C.i);
  }
}

public class C {
  public static void main(String[] args){
    Student stu1 = new Student(18,"小紅",580);
    Student stu2 = new Student(18,"小黑",620);
    System.out.println("有" + Student.p_total + "個(gè)學(xué)生");
    System.out.println("學(xué)費(fèi)總收入：" + Student.get_total_fee());
  }
}

//定義一個(gè)學(xué)生類
class Student{
  public int age;
  public String name;
  public double fee; //學(xué)費(fèi)
  public static int p_total = 0;
  public static double total_fee; //總學(xué)費(fèi)

  public Student(int age, String name, double fee)
  {
    p_total++;
    this.age = age;
    this.name = name;
    this.total_fee += fee;
  }

  //靜態(tài)方法
  //Java中規(guī)則：類變量原則上用類方法去訪問
  public static double get_total_fee()
  {
    return total_fee;
  }
}