JAVA类变量及类方法代码实例详解

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

    Child ch1 = new Child(12,"小小");
    ch1.joinGame();
    Child ch2 = new Child(13,"小红");
    ch2.joinGame();
    //调用类变量
    System.out.println("一共有" + Child.total+ "小朋友");
  }
}

class Child{
  public int age;
  public String name;

  //total是静态变量,因此他可以被任何类调用
  public static int total = 0;

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

  public void joinGame()
  {
    total++;
    System.out.println("有一个小朋友加进来！");
  }
}

public class C {

  static int i = 1;
  static
  {
    System.out.println("静态区域块被执行一次");
    //该静态区域块,只被执行一次，也不会因创建对象而触发
    i++;
  }
  public C()
  {
    System.out.println("构造函数域块被执行一次");
    i++;
  }

  public static void main(String[] args){

    C t1 = new C();
    System.out.println("输出第一个i的值为：" + C.i);
    C t2 = new C();
    System.out.println("输出第二个i的值为：" + C.i);
  }
}

public class C {
  public static void main(String[] args){
    Student stu1 = new Student(18,"小红",580);
    Student stu2 = new Student(18,"小黑",620);
    System.out.println("有" + Student.p_total + "个学生");
    System.out.println("学费总收入：" + Student.get_total_fee());
  }
}

//定义一个学生类
class Student{
  public int age;
  public String name;
  public double fee; //学费
  public static int p_total = 0;
  public static double total_fee; //总学费

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

  //静态方法
  //Java中规则：类变量原则上用类方法去访问
  public static double get_total_fee()
  {
    return total_fee;
  }
}