面向对象14static关键字详解

package com.oop.demo07;

public  class Person {

    {
        //2.赋初值
        //代码块（匿名代码块）
        System.out.println("匿名代码块");
    }

    static {
        //1.只执行一次
        //静态代码块
        System.out.println("静态代码块");
    }
        //3
    public Person() {
        System.out.println("构造方法");
    }

    public static void main(String[] args) {
        Person person1 = new Person();
        System.out.println("=====================");
        Person person2 = new Person();
    }
}

package com.oop.demo07;

//static
public class Student {

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

    public void run(){

    }
    public static void go(){

    }

    public static void main(String[] args) {
        go();
    }
}

package com.oop.demo07;

//静态导入包
import static java.lang.Math.random;
import static java.lang.Math.PI;

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