Java initializing fields order 2017-12-26 08:11
If you can not make sure the execution order of block, static-block and constructor. This blog will write a demo to help you understand the order of initializing fields.
Code
public class Super {
public Super() {
System.out.println("Super constructor");
}
{
System.out.println("Super block");
}
static {
System.out.println("static Super");
}
}
public class Child extends Super {
public Child() {
System.out.println("Child constructor");
}
{
System.out.println("Child block");
}
static {
System.out.println("static Child");
}
}
public class Client {
public static void main(String[] args) {
new Child();
System.out.println("----init second child----");
new Child();
}
}
The output is here
static Super
static Child
Super block
Super constructor
Child block
Child constructor
----init second child----
Super block
Super constructor
Child block
Child constructor
There are several rules when initializing fields
statkc-blockwill executed before the Object first used.blockwill executed firstly when the instance is created.constructorwill executed when allblock(static and normalblock) execute finish.