current position：Home>Java FAQ -- string
Java FAQ -- string
2022-01-26 22:24:12 【Yan Long】
String is a common data type . stay Java in , Common string types include
from String You can see the source code of ,String Use an array to store the contents of a string , Arrays use keywords final modification , Therefore, the contents of the array are immutable , Use String The value of the defined string is also immutable .
because String The value of type is immutable , So every time String Any modification will create a new String object , Leads to inefficiency and takes up a lot of memory space .
tips: string Data is stored in a constant pool , Not in the pile also Not in the stack .
StringBuffer and StringBuilder
StringBuffer and StringBuilder All are AbstractStringBuilder Subclasses of , Also use an array to store the contents of a string , Because the array does not use keywords final modification , Therefore, the contents of the array are variable ,StringBuffer and StringBuilder Are all variable types , You can modify the contents of the string , And no new objects will be created due to modification .
When the content of the string needs to be modified frequently , You should use StringBuffer or StringBuilder, Significantly better than... In terms of time and space String.
StringBuffer and StringBuilder What are the differences ？ You can see from the source code ,StringBuffer Keywords are used for defined methods or called methods synchronized modification , and StringBuilder The method does not use keywords synchronized modification . because StringBuffer Add synchronization lock to the method , Therefore, its efficiency is slightly lower than StringBuilder, But in a multithreaded environment ,StringBuilder Thread safety cannot be guaranteed , therefore StringBuffer It's a better choice .
String It's an immutable type , Every time the String Any modification will create a new String object , Leads to inefficiency and takes up a lot of memory space , therefore String For string constants , It is not suitable for situations that require a large number of modifications to the string . StringBuffer It's a variable type , You can modify the contents of the string without creating new objects , And StringBuffer It's thread safe , Suitable for multi-threaded environment . StringBuilder It's a variable type , And StringBuffer be similar , In a single threaded environment StringBuilder The efficiency is slightly higher than StringBuffer, But in a multithreaded environment StringBuilder Thread safety is not guaranteed , therefore StringBuilder Not suitable for multi-threaded environment .
author[Yan Long],Please bring the original link to reprint, thank you.
The sidebar is recommended
- Spring IOC container loading process
- [thinking] the difference between singleton mode and static method - object-oriented programming
- Hadoop environment setup (MySQL environment configuration)
- 10 minutes, using node JS creates a real-time early warning system for bad weather!
- Git tool
- Force deduction algorithm - 92 Reverse linked list II
- What is the sub problem of dynamic programming?
- C / C + +: static keyword summary
- Idea does not have the artifacts option when configuring Tomcat
- Anaconda can't open it
guess what you like
I don't know how to start this
Matlab simulation of transportation optimization algorithm based on PSO
MySQL slow log optimization
[Vue] as the window is stretched (larger, smaller, wider and higher), the text will not be displayed
Popular Linux distributions for embedded computing
Suzhou computer research
After installing SSL Certificate in Windows + tomcat, the domain name request is not successful. Please answer!!
Implementation time output and greetings of jQuery instance
The 72 year old uncle became popular. Wu Jing and Guo fan made his story into a film, which made countless dreamers blush
How to save computer research
- Springboot implements excel import and export, which is easy to use, and poi can be thrown away
- The final examination subjects of a class are mathematical programming, and the scores are sorted and output from high to low
- Two pronged approach, Tsinghua Professor Pro code JDK and hotspot source code notes, one-time learning to understand
- C + + recursive knapsack problem
- The use of GIT and GitHub and the latest git tutorial are easy to understand -- Video notes of crazy God speaking
- PostgreSQL statement query
- Ignition database test
- Context didn't understand why he got a high salary?, Nginxfair principle
- Bootstrap switch switch control user's guide, springcloud actual combat video
- A list that contains only strings. What other search methods can be used except sequential search
- [matlab path planning] multi ant colony algorithm grid map path planning [including GUI source code 650]
- [matlab path planning] improved genetic algorithm grid map path planning [including source code phase 525]
- Iinternet network path management system
- Appium settings app is not running after 5000ms
- Reactnative foundation - 07 (background image, status bar, statusbar)
- Reactnative foundation - 04 (custom rpx)
- If you want an embedded database (H2, hsql or Derby), please put it on the classpath
- When using stm32g070 Hal library, if you want to write to flash, you must perform an erase. If you don't let it, you can't write continuously.
- Linux checks where the software is installed and what files are installed
- SQL statement fuzzy query and time interval filtering
- 69. Sqrt (x) (c + + problem solving version with vs runnable source program)
- Fresh students are about to graduate. Do you choose Java development or big data?
- Java project: OA management system (java + SSM + bootstrap + MySQL + JSP)
- Titanic passenger survival prediction
- Vectorization of deep learning formula
- Configuration and use of private image warehouse of microservice architect docker
- For someone, delete return 1 and return 0
- How does Java dynamically obtain what type of data is passed? It is used to judge whether the data is the same, dynamic data type
- How does the database cow optimize SQL?
- [data structure] chain structure of binary tree (pre order traversal) (middle order traversal) (post order traversal) (sequence traversal)
- Webpack packaging optimization solution
- 5. Operation element
- Detailed explanation of red and black trees
- redhat7. 9 install database 19C
- Blue Bridge Cup notes: (the given elements are not repeated) complete arrangement (arrangement cannot be repeated, arrangement can be repeated)
- Detailed explanation of springboot default package scanning mechanism and @ componentscan specified scanning path
- How to solve the run-time exception of test times
- Detailed explanation of k8s management tool kubectl
- Android system view memory command