构造函数及其成员变量初始化顺序详解

package demo;
/**
 * 
 * @author Administrator
 *	think in java the forth edition
 * 
 */
public class ConstractInit extends PortableLunch
{
	private Meal m=new Meal();
	private Cheese cheese=new Cheese();
	private Bread b=new Bread();
	
	public ConstractInit()
	{
		/* 
                 *  1.在任何事物发生之前，将分配给对象的存储空间初始化成二进制的0
		 *  2.调用构造方法时，默认会调用父类的构造方法，此时成员变量还未初始化,此步骤会一直递归调用父类的构造方法，
		 *	    直到根基类（Bread）没有父类（所有的成员变量均为初始化）
		 *  3. 到达根基类后，然后开始初始化成员变量，成员变量初始化完成之后，执行构造器主体，
		 *    主体调用完成之后然后递归开始（与第一步相反方向）初始化其子类的成员变量，直到最底层的子类(此示例为ConstractInit)
		 *  4    最底层的子类(ConstractInit)成员变量初始化完成之后，开始执行自身构造器主体
		 */
		System.out.println("ConstractInit");
	}
	public static void main(String[] args)
	{
		new ConstractInit();
	}

}

class Meal
{
	private int a=initMeal();
	Meal()
	{
		System.out.println("Meal");
	}
	
	private int initMeal()
	{
		System.out.println("Meal attribute initazlized");
		return 1;
	}
}

class Bread
{
	private int b=initBread();
	public Bread()
	{
		System.out.println("Bread");
	}
	
	private int initBread()
	{
		System.out.println("Bread attribute initazlized");
		return 1;
	}
}

class Cheese
{
	private int c=initCheese();
	public Cheese()
	{
		System.out.println("Cheese");
	}
	
	private int initCheese()
	{
		System.out.println("Cheese attribute initazlized");
		return 1;
	}
}

class Lettuce
{
	public Lettuce()
	{
		System.out.println("Lettuce");
	}
}

class Lunch extends Meal
{
	private int d=initLunch();
	public Lunch()
	{
		System.out.println("Lunch");
	}
	
	public int initLunch()
	{
		System.out.println("Lunch attribute initazlized");
		return 1;
	}
	
}

class PortableLunch extends Lunch
{
	private int e=initPortableLunch();
		PortableLunch()
		{
			System.out.println("PortableLunch");
		}
		
		public int initPortableLunch()
		{
			System.out.println("PortableLunch attribute initazlized");
			return 1;
		}
}

最后打印结构为：

Meal attribute initazlized
Meal
Lunch attribute initazlized
Lunch
PortableLunch attribute initazlized
PortableLunch
Meal attribute initazlized
Meal
Cheese attribute initazlized
Cheese
Bread attribute initazlized
Bread
ConstractInit