类初始化顺序探究

最新推荐文章于 2025-11-29 09:26:02 发布

原创最新推荐文章于 2025-11-29 09:26:02 发布 · 106 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#ITeye #.net

CoreJava 专栏收录该内容

5 篇文章

订阅专栏

本文详细解析了Java类初始化过程中的顺序，从类属性、静态代码块到对象创建的细节，帮助开发者理解类加载和初始化的流程。

1.本例子借用thinkingInJava第4版中文版P163中PolyConstructors.java例子修改后，说明一定问题：

该类中包含：静态属性、静态代码块、成员变量、普通代码块、父子类关系、子类重写父类方法

package com.iteye.bobby.base;

import static net.mindview.util.Print.*;

class Glyph {

	private static String baseStr = "static String field";
	
	static {
		System.out.println("baseStr = " + baseStr);
		System.out.println("Glyph.enclosing_method(static)");
	}
	
	{
		System.out.println("Glyph.enclosing_method(noraml)");
	}
	
	Glyph() {
		print("Glyph() before draw()");
		draw();
		print("Glyph() after draw()");
	}
	
	void draw() {
		print("Glyph.draw()");
	}
}

class RoundGlyph extends Glyph {
	private int radius = 1;
	private Glyph glyph = new Glyph();//成员变量赋值时创建对象

	static {
		System.out.println("RoundGlyph.enclosing_method(static)");
	}
	
	{
		System.out.println("RoundGlyph.enclosing_method(noraml)");
		System.out.println(" radius =  " + radius);
		System.out.println("new glyph() = " + glyph);
	}
	
	RoundGlyph(int r) {
		radius = r;
		print("RoundGlyph.RoundGlyph(), radius = " + radius);
	}

	void draw() {
		print("RoundGlyph.draw(), radius = " + radius);
	}
}

public class PolyConstructors {
	public static void main(String[] args) {
		new RoundGlyph(5);
	}
}

Result：

baseStr = static String field

Glyph.enclosing_method(static)

RoundGlyph.enclosing_method(static)

Glyph.enclosing_method(noraml)

Glyph() before draw()

RoundGlyph.draw(), radius = 0

Glyph() after draw()

Glyph.enclosing_method(noraml)

Glyph() before draw()

Glyph.draw()

Glyph() after draw()