Thinking in Java 之 继承与初始化

在初始化顺序中，首先先初始化根基类中的static，然后是导出类， 直到导出类static初始化完成。在本例中，首先初始化Insect基类中的static,即x1,此时打印出“static Insect.x1 initialized”；而后是导出类（子类）static x2初始化，此时打印出static Beetle.x2 initialized；最后是主类static初始化，及static main()，此时打印出Beetle constructor；然后父类私有成员初始化，子类私有成员初始化，此时打印出Beetle.k initialized；最后打印出子类构造函数。

class Insect{    private int i = 9;    protected int j;    Insect(){        System.out.println("i = " + i + ", j = " + j);        j = 39;        System.out.println("x1 = " + x1);    }    static int printInit(String s){                         //成员函数        System.out.println(s);        return 47;    }    private static int x1 = printInit("static Insect.x1 initialized");      //此时x1 = 47}public class example_272 extends Insect{    private int k = printInit("Beetle.k initialized");    public example_272(){        System.out.println("k = " + k);        System.out.println("j = " + j);        System.out.println("x2 = " + x2);    }    private static int x2 = printInit("static Beetle.x2 initialized");          //此时x2=47    public static void main(String args[]){        System.out.println("Beetle constructor");        example_272 b = new example_272();    }}