The order in which java objects are initialized
1. Several parts involved in initialization
The Java object not only calls its own constructor during initialization, but also involves static statement blocks , instance statement block, static variable initialization, member variable initialization and other execution issues. The initialization sequence refers to the execution sequence of these five parts.
2.Demo
package com.javase.classtest;public class InitializationSequence {static { System.out.println("静态语句块"); }static MyInnerClass in = new MyInnerClass("静态变量s"); MyInnerClass in01 = new MyInnerClass("a"); { System.out.println("实例语句块"); } MyInnerClass in02 = new MyInnerClass("b");public InitializationSequence() { System.out.println("构造函数"); } @SuppressWarnings("unused")public static void main(String[] args) { InitializationSequence obj01 = new InitializationSequence(); System.out.println("-----------------------------------"); InitializationSequence obj02 = new InitializationSequence(); } }class MyInnerClass {public MyInnerClass(String description) { System.out.println("成员变量初始化::" + description); } }
Execution result:
Analysis:
Static statement block: executed when the class is loaded into the JVM, because the prerequisite for the JVM to use the class is that the class is loaded into JVM virtual machine, so the static statement block is executed first, the class is only loaded once, and the static statement block is only executed once.
Static variable initialization: Since static variables are shared by all instances of the class and do not depend on specific objects, they are not initialized when the object is created, but Initialized when the class is loaded, the initialization sequence is after the static statement block and is only executed once.
Instance statement block: executed before the constructor method, executed once each time the constructor method is called. The execution order is after the initialization of static variables, with reference to the initialization of member variables. There is no absolute order. The actual order depends on the order of definition. If it is defined first, it will be executed before the member variable is initialized; if it is defined later, it will be executed after the member variable is initialized. executed later.
Member variable initialization: executed before the constructor, and executed once each time the constructor is called. Execution order After initialization of static variables, the execution order relative to instance statement blocks depends on the definition order.
Construction method: executed last.
It can be seen from the above that, the execution order of Java object initialization is: static statement block>static variable initialization>instance statement block/member variable initialization >The relative execution order of constructors, instance statement blocks and member variable initialization depends on the order of definition.
The above is the detailed content of The order in which java objects are initialized. For more information, please follow other related articles on the PHP Chinese website!

Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

AI Hentai Generator
Generate AI Hentai for free.

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Hot Topics

Guide to Square Root in Java. Here we discuss how Square Root works in Java with example and its code implementation respectively.

Guide to Perfect Number in Java. Here we discuss the Definition, How to check Perfect number in Java?, examples with code implementation.

Guide to Random Number Generator in Java. Here we discuss Functions in Java with examples and two different Generators with ther examples.

Guide to Weka in Java. Here we discuss the Introduction, how to use weka java, the type of platform, and advantages with examples.

Guide to the Armstrong Number in Java. Here we discuss an introduction to Armstrong's number in java along with some of the code.

Guide to Smith Number in Java. Here we discuss the Definition, How to check smith number in Java? example with code implementation.

In this article, we have kept the most asked Java Spring Interview Questions with their detailed answers. So that you can crack the interview.

Java 8 introduces the Stream API, providing a powerful and expressive way to process data collections. However, a common question when using Stream is: How to break or return from a forEach operation? Traditional loops allow for early interruption or return, but Stream's forEach method does not directly support this method. This article will explain the reasons and explore alternative methods for implementing premature termination in Stream processing systems. Further reading: Java Stream API improvements Understand Stream forEach The forEach method is a terminal operation that performs one operation on each element in the Stream. Its design intention is
