關於java類執行的順序

以前面試或作題的時候老是會遇到問一個子類繼承一個父類後，裏面各自有靜態代碼塊，構造器，方法等的執行順序的問題，老是感受好像是什麼什麼樣，如今本身來寫個例子就知道了：

父類：

public class FatherDemo {
	
	public static int f1 = 3;
	
	private static String name = "father";
	
	public FatherDemo(){
		System.out.println("===f1:"+f1+"=====name:"+name+"========");
		System.out.println("========我是Father類==無慘構造器=============");
	}
	
	
	public FatherDemo(String name){
		System.out.println("===f1:"+f1+"=====name:"+name+"========");
		System.out.println("========我是Father類==帶參構造器=============");
		this.name = name;
		System.out.println("===f1:"+f1+"=====name:"+name+"========");
	}
	
	
	static{
		System.out.println("===f1:"+f1+"=====name:"+name+"========");
		System.out.println("========我是Father類==static代碼塊=============");
		
	}
	
	{
		System.out.println("===f1:"+f1+"=====name:"+name+"========");
		System.out.println("========我是Father類==代碼塊=============");
		
	}
	
	public static void mothod0(){
		System.out.println("===f1:"+f1+"=====name:"+name+"========");
		System.out.println("========我是Father類==static方法mothod0=============");
	}
	public void method(){
		System.out.println("===f1:"+f1+"=====name:"+name+"========");
		System.out.println("========我是Father類==method方法=============");
	}
	
}

子類：

public class ChildDemo extends FatherDemo{

	public static int f2 = 3;
	
	private static String name = "child";
	
	public ChildDemo(){
		System.out.println("===f1:"+f1+"=====name:"+name+"========");
		System.out.println("========我是ChildDemo類==無慘構造器=============");
	}
	
	
	public ChildDemo(String name){
		System.out.println("===f1:"+f1+"=====name:"+name+"========");
		System.out.println("========我是ChildDemo類==帶參構造器=============");
		this.name = name;
		System.out.println("===f1:"+f1+"=====name:"+name+"========");
	}
	
	
	static{
		System.out.println("===f1:"+f1+"=====name:"+name+"========");
		System.out.println("========我是ChildDemo類==static代碼塊=============");
		
	}
	
	{
		System.out.println("===f1:"+f1+"=====name:"+name+"========");
		System.out.println("========我是ChildDemo類==代碼塊=============");
		
	}
	
     	public static void mothod0(){
		System.out.println("===f1:"+f1+"=====name:"+name+"========");
		System.out.println("========我是ChildDemo類==static方法mothod0=============");
	}

	public void method(){
		System.out.println("===f1:"+f1+"=====name:"+name+"========");
		System.out.println("===4444=====我是ChildDemo類==method方法=============");
	}
	
}

測試類：

public static void main(String[] args) {
	ChildDemo child = new ChildDemo();
	child.method();
	System.out.println();
	ChildDemo demo = new ChildDemo("demo");
	demo.method();
}

執行結果： ===f1:3=====name:father======== ========我是Father類==static代碼塊============= ===f1:3=====name:child======== ========我是ChildDemo類==static代碼塊============= ===f1:3=====name:father======== ========我是Father類==代碼塊============= ===f1:3=====name:father======== ========我是Father類==無慘構造器============= ===f1:3=====name:child======== ========我是ChildDemo類==代碼塊============= ===f1:3=====name:child======== ========我是ChildDemo類==無慘構造器============= ===f1:3=====name:child======== ===4444=====我是ChildDemo類==method方法=============

===f1:3=====name:father======== ========我是Father類==代碼塊============= ===f1:3=====name:father======== ========我是Father類==無慘構造器============= ===f1:3=====name:child======== ========我是ChildDemo類==代碼塊============= ===f1:3=====name:demo======== ========我是ChildDemo類==帶參構造器============= ===f1:3=====name:demo======== ===f1:3=====name:demo======== ===4444=====我是ChildDemo類==method方法=============

由此能夠看出，執行的順序爲：

父類靜態屬性 --》父類靜態代碼塊--》子類靜態屬性--》子類靜態代碼塊--》父類代碼塊--》父類無參構造--》子類代碼塊--》子類無參構造--》子類方法

如上發現父類和子類的靜態方法都沒有執行，有意思的是當我實例化子類的帶參構造的時候，父類的子類的靜態代碼塊就不執行了，並且執行的順序變爲了： 父類代碼塊--》父類無參構造器--》子類代碼塊--》子類帶參構造器--》子類method方法