[Java] Java类属性和对象属性的初始化顺序

Java类属性和对象属性的初始化顺序如下：

(1) 类属性（静态变量）定义时的初始化

(2) static块中的初始代码 

(3) 对象属性（非静态变量）定义时的初始化

(4) 构造方法（函数）中的初始化代码

下面举例说明：

<pre name="code" class="java">public class test {//类属性static String a = "string-a";static String b;//对象属性String c = "string-c";String d;//static块static{printStatic("before static");b = "string-b";printStatic("after static");}public static void printStatic(String title){System.out.println("***********"+title+"*****************");System.out.println("a = \"" + a + "\"");System.out.println("b = \"" + b + "\"");}//构造函数public test(){print("before constructor");d = "string -d";print("after constructor");}public void print(String title){System.out.println("************"+ title + "****************");System.out.println("a = \"" + a + "\"");System.out.println("b = \"" + b + "\"");System.out.println("c = \"" + c + "\"");System.out.println("d = \"" + d + "\"");}public static void main(String[] args) {new test();}}

上面程序的运行结果如下：

***********before static*****************a = "string-a" b = "null"***********after static*****************a = "string-a"b = "string-b"************before constructor****************a = "string-a"b = "string-b"c = "string-c"d = "null"************after constructor****************a = "string-a"b = "string-b"c = "string-c"d = "string -d"

由此可以看出类属性与对象属性的初始化顺序。