Java block, static block, constructor, inherited execution sequence

Http://d-y-zh.javaeye.com/blog/607027

 

Non-static statement block, first seen.

 

Public class test
{
Public static void main (string [] AGRs)
{
Son son = new son ();
}
}

Class super
{
Public super ()
{
System. Out. Print ("A/T ");
}
{
System. Out. Print ("B/T ");
}
Static
{
System. Out. Print ("C/T ");
}
}

Class son extends super
{
Public son ()
{
System. Out. Print ("d/t ");
}
{
System. Out. Print ("E/t ");
}
Static
{
System. Out. Print ("F/T ");
}
}

Static objects belong to classes, and non-static objects belong to instances.

The static statement is executed first before it is non-static.

In the above example, we also need to consider the inheritance issue.

First, the parent class static --> C

Then the subclass static --> F

A non-static block can be considered as the first part after the parent class constructor is executed in the constructor. (The first line of the constructor has a default Super () call, which is to call the parent class constructor ).

Execute the parent class constructor at this time:

Non-static block of the parent class --> B

Parent class constructor block -->

Then the sub-class constructor:

Subclass non-static block --> E

Subclass constructor block --> d

Summary:

C f B A E d

It is worth noting that static things are executed only once, that is, when classes are loaded.

If the main function is changed:

Java code

Public static void main (string [] AGRs) {son = new son (); son son2 = new son ();}

The execution result is as follows:

C f B a e d B A e d