Java-based constructor and comparison between constructor and constructor code blocks

[Java] class Demo {public Demo () // Constructor (method) {int a = 90; System. out. println ("constructor a =" + a) ;}{// constructor code block int a = 80; // no object is created and will not run. system. out. println ("construct code a =" + a);} public static void main (String [] args) {System. out. println ("running result"); new Demo () ;}} running result:

The running result shows that the code block of the class instance construction takes precedence over the constructor running constructor: 1. the class names are consistent and cannot be modified using static. After being modified by void, it is a general function. 2. A class can have multiple constructors, which are called according to the shape parameters. 3. return is allowed, but no content is returned. purpose: Initialize an object.