static关键字及代码块

package com.study.oop.demo08;

public class Student {

    private static int age;//静态变量
    private double score;//非静态变量

    public void read(){
        System.out.println("read");
    }

    public static void watch(){
        System.out.println("watch");
    }

    public static void main(String[] args) {
        Student student = new Student();
        System.out.println(Student.age);
        //System.out.println(score);不能这么调用
        System.out.println(student.age);
        System.out.println(student.score);

        watch();
        student.read();
    }
}

package com.study.oop.demo08;

//public final class Person 类被final定义了，无法被继承
public class Person {

    //加载顺序： 静态代码块 >> 匿名代码块 >> 构造器
    //赋初始值
    {
        System.out.println("匿名代码块");
    }

    //只会执行一次
    static {
        System.out.println("静态代码块");
    }

    public Person() {
        System.out.println("构造器");
    }

    public static void main(String[] args) {
        Person p1 = new Person();
        Person p2 = new Person();

    }
}

package com.study.oop.demo08;

import static java.lang.Math.random;//import java.lang.Math.random;直接导入random报错，可通过加static关键字解决

public class Test {
    public static void main(String[] args) {
        System.out.println(Math.random());
    }
}