Static code block in Java, Construction code block, construction method detailed _java

Run the following code and observe the results:

Package com.test;

public class Hellob extends Helloa {public
  
  Hellob () {
  }

  {
    System.out.println ("I ' M B class");
  }
  
  static {
    System.out.println ("Static B");
  }

  public static void Main (string[] args) {
    new Hellob ();
  }
}

Class Helloa {public
  
  Helloa () {
  }

  {
    System.out.println ("I ' M A class");
  }
  
  static {
    System.out.println ("Static A");
  }
  

The results are as follows:

Static a
static B
i ' M A class
I ' M B class

Analytical:

1. Static code block: is in the class loading process of the third stage of initialization, the main purpose is to give the class variable to the initial value.

2. Construction code block: is independent, must rely on the carrier to run, Java will put the construction code block in front of each construction method, to instantiate some common instance variables, reduce the amount of code.

3. Construct method: for instantiating variables.

Summary:

1 is class-level, 2, 3 is instance-level, so 1 takes precedence 2, 3.

Their order of execution is 1>2>3;

Above this Java static code block, the construction code block, the construction method detailed explanation is small arranges to share to everybody's content, hoped can give everybody a reference, also hoped that everybody supports the cloud habitat community.