Guice
A new type of Juice
Put simply, Guice alleviates the need for factories and the use of new in your Java code. Think of Guice’s @Inject as the new new. You will still need to write factories in some cases, but your code will not depend directly on them. Your code will be easier to change, unit test and reuse in other contexts.
Guice embraces Java’s type safe nature, especially when it comes to features introduced in Java 5 such as generics and annotations. You might think of Guice as filling in missing features for core Java. Ideally, the language itself would provide most of the same features, but until such a language comes along, we have Guice.
Guice helps you design better APIs, and the Guice API itself sets a good example. Guice is not a kitchen sink. We justify each feature with at least three use cases. When in doubt, we leave it out. We build general functionality which enables you to extend Guice rather than adding every feature to the core framework.
Guice vs Spring
Spring and Google Guice are two powerful dependency injection frameworks in use today. Both frameworks fully embrace the concepts of dependency injection, but each has its own way of implementing them. Although Spring provides many benefits, it was created in a pre-Java-5 world. The Guice framework takes DI to the next level.
The advent of Java 5 brought significant changes to the language like generics and annotations: features that enhance the power of Java static typing. Guice is a DI framework that was built from the ground up with the intent to take full advantage of these new features and that has focused on one primary goal: to do dependency injection well.
Guice aims to make development and debugging easier and faster, not harder and slower. In that vein, Guice steers clear of surprises and magic. You should be able to understand code with or without tools, though tools can make things even easier. When errors do occur, Guice goes the extra mile to generate helpful messages.
core differences between the two, and see why I prefer to use Guice.
- Living in XML Hell
- Eliminating reliance on String identifiers
- Preferring Constructor Injection
Although Spring and Guice both support constructor and setter injection, each framework has a preference. Spring has long favored setter injection. Back in the early days of Spring, the authors believed the lack of argument names and default arguments in constructor injection reduced clarity. In addition, constructor injection makes it difficult to have optional dependencies, requires dependencies to be configured in a specific order, and forces subclasses to deal with superclass dependencies. Using setter injection eliminates these problems, and so Spring favors that approach.
The Guice authors saw difficulties with setter injection. One problem is immutability: it is impossible to make immutable a class that uses setter injection. Constructor injection, on the other hand, makes the creation of immutable classes easy, an important consideration in writing multi-threaded applications. In addition, optional dependencies, while perhaps convenient, can introduce confusion about how a class is configured at runtime. Configuring a class through setter injection can often lead to missed required dependencies. Though Spring does provide a @Required annotation to solve this problem, using constructor injection eliminates it by default.
Constructor injection also makes a class’s dependencies immediately clear at a glance. If you’re writing or modifying a unit test, it’s easy to read what the system-under-test needs. Lastly, because Guice uses types to wire classes together, constructor argument order isn’t an issue. You can feel free to reorder them how you want without needing to modify configuration code at all.
The potential drawbacks posed by setter injection outweigh the benefits in many common scenarios, and so Guice established a best practice of favoring constructor injection instead. Its API is well-suited to that approach. But if you should choose to switch from one form of injection to the other, Guice makes that easy too. Changing from setter to constructor injection or vice versa is simply a matter of modifying the class in question. Unlike in Spring, you need never touch a configuration file.
- Nullifying NullPointerExceptions
Null is easily one of the most non-communicative return values possible from a method call. Guice hates nulls as much as I do. By default, Guice refuses to inject a null into any object, and if an accidental null shows up during wiring, it fails-fast with a ProvisionException. Guice does allow for the exception case by permitting fields to be annotated with @Nullable, but this is discouraged.
- Intruding into the domain
Guice aims to eliminate all of this boilerplate without sacrificing maintainability. With Guice, you implement modules. Guice passes a binder to your module, and your module uses the binder to map interfaces to implementations. The following module tells Guice to map Service to ServiceImpl in singleton scope:
public class MyModule implements Module {
public void configure(Binder binder) {
binder.bind(Service.class)
.to(ServiceImpl.class)
.in(Scopes.SINGLETON);
} }
A module tells Guice what we want to inject. Now, how do we tell Guice where we want it injected? With Guice, you annotate constructors, methods and fields with @Inject.
public class Client {
private final Service service;
@Inject
public Client(Service service) {
this.service = service;
}
public void go() {
service.go();
} }
Guice vs. Dependency Injection By Hand
As you can see, Guice saves you from having to write factory classes. You don’t have to write explicit code wiring clients to their dependencies. If you forget to provide a dependency, Guice fails at startup. Guice handles circular dependencies automatically. Guice enables you to specify scopes declaratively. For example, you don’t have to write the same code to store an object in the HttpSession over and over. In the real world, you often don’t know an implementation class until runtime. You need meta factories or service locators for your factories. Guice addresses these problems with minimal effort. When injecting dependencies by hand, you can easily slip back into old habits and introduce direct dependencies, especially if you’re new to the concept of dependency injection. Using Guice turns the tables and makes doing the right thing easier. Guice helps keep you on track.
Guice annotations
When possible, Guice enables you to use annotations in lieu of explicit bindings and eliminate even more boilerplate code. Back to our example, if you need an interface to simplify unit testing but you don’t care about compile time dependencies, you can point to a default implementation directly from your interface.
@ImplementedBy(ServiceImpl.class)
public interface Service {
void go();
}
If a client needs a Service and Guice can’t find an explicit binding, Guice will inject an instance of ServiceImpl.
By default, Guice injects a new instance every time. If you want to specify a different scope, you can annotate the implementation class, too.
@Singleton
public class ServiceImpl implements Service {
public void go() {
... }
}
Architectural Overview
We can break Guice’s architecture down into two distinct stages: startup and runtime. You build an Injector during startup and use it to inject objects at runtime.
Startup
You configure Guice by implementing Module. You pass Guice a module, Guice passes your module a Binder, and your module uses the binder to configure bindings. A binding most commonly consists of a mapping between an interface and a concrete implementation. For example:
public class MyModule implements Module {
public void configure(Binder binder) {
// Bind Foo to FooImpl. Guice will create a new
// instance of FooImpl for every injection.
binder.bind(Foo.class).to(FooImpl.class);
// Bind Bar to an instance of Bar.
Bar bar = new Bar();
binder.bind(Bar.class).toInstance(bar);
}
Injecting Providers
With normal dependency injection, each type gets exactly one instance of each of its dependent types. The RealBillingService gets one CreditCardProcessor and one TransactionLog. Sometimes you want more than one instance of your dependent types. When this flexibility is necessary, Guice binds a provider. Providers produce a value when the get() method is invoked:
public interface Provider<T> {
T get();
}
@Provides Methods
When you need code to create an object, use an @Provides method. The method must be defined within a module, and it must have an @Provides annotation. The method’s return type is the bound type. Whenever the injector needs an instance of that type, it will invoke the method.
public class BillingModule extends AbstractModule {
@Override
protected void configure() {
...
}
@Provides
TransactionLog provideTransactionLog() {
DatabaseTransactionLog transactionLog = new DatabaseTransactionLog();
transactionLog.setJdbcUrl("jdbc:mysql://localhost/pizza");
transactionLog.setThreadPoolSize(30);
return transactionLog;
}
}
If the @Provides method has a binding annotation like @PayPal or @Named(“Checkout”), Guice binds the annotated type. Dependencies can be passed in as parameters to the method. The injector will exercise the bindings for each of these before invoking the method.
@Provides @PayPal
CreditCardProcessor providePayPalCreditCardProcessor(
@Named("PayPal API key") String apiKey) {
PayPalCreditCardProcessor processor = new PayPalCreditCardProcessor();
processor.setApiKey(apiKey);
return processor;
}
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Summary In windows operating system, if you want to get your CPU name, core, 64bit and speed in command line. Just follow below actions:
JetBrains/IntelliJ tips
Be a good person in real life, not in social media
Whitelabel Error Page
Summary Whitelabel Error Page is the default error page in Spring Boot web app. It provide a more user-friently error page whenever there are any issues when...
Google maps no photos reviews
Summary
谷歌地图里面照片的评论显示不出来
If you’d like to view solution in YouTube, check out at https://youtu.be/ICiwuqJ-yU8
Shall I still need booster even after I got dose 3?
The greatest wealth is health!
Debts in a nutshell
A debt security represents a debt owed by the issuer to an investor. Here, the investor acts as a lender to the issuer which may be a government, organisatio...
2020
How to process data from S3 download URL
S3 download URL As you know, AWS S3 object can be downloaded/processed by S3 download URL. I’m showing you two examples on how to process S3 Object by NIO f...
Debug Stuck IntelliJ
What happened to a debug job hanging in IntelliJ (IDEAS) IDE? You may find when you try to debug a class in Intellij but it stuck there and never proceed, e....
Awesome Kotlin
Difference with Scala Kotlin takes the best of Java and Scala, the response times are similar as working with Java natively, which is a considerable advantag...
Awesome tips for Chrome
Shortcuts & tips
JVM热身
此文是作者英文原文的翻译文章，英文原文在：http://todzhang.com/posts/2018-06-10-jvm-warm-up/
Awesome tips and shortcuts for Slack
Shortcuts for Slack
Awesome Reactive programming
Key points of Reactive Programming
Awesome Swift for iOS
Frame in Swift
Mock in kotlin
Argument Matching & Answers For example, you have mocked DOC with call(arg: Int): Intfunction. You want to return 1 if argument is greater than 5 and -1 ...
Mock in kotlin
Argument Matching & Answers For example, you have mocked DOC with call(arg: Int): Intfunction. You want to return 1 if argument is greater than 5 and -1 ...
Docker
Dockers Concepts
How to decode path parameters in All REST WebServices calls
How to decode path parameters in All REST WebServices calls
Curl
Linux Curl command
AOP
The concept of join points as matched by pointcut expressions is central to AOP, and Spring uses the AspectJ pointcut expression language by default.
Micrometer notes
As a general rule it should be possible to use the name as a pivot. Dimensions allow a particular named metric to be sliced to drill down and reason about th...
Pigeons in holes principle
# Pigeonhole principle
Awesome solutions for algorithm questions
你就会发现只要涉及递归的问题，都是 树的问题。
A Facial Recognition utility in a dozen of LOC
A Facial Recognition utility in a dozen of python LOC (Lines Of Code)
Awesome SSL certificates and HTTPS
What’s TLS TLS (Transport Layer Security) and its predecessor, SSL (Secure Sockets Layer), are security protocols designed to secure the communication betwee...
JVM warm up by Escape Analysis
Why JVM need warm up I don’t know how and why you get to this blog. But I know the key words in your mind are “warm” for JVM. As the name “warm up” suggested...
Java Concurrent Column 2
This is the second half about Java Concurrent of my blog
Java Concurrent
This blog is about noteworthy pivot points about Java Concurrent Framework Back to Java old days there were wait()/notify() which is error prone, while fr...
Algorithm notes from Leecode – 1
Algorithm Leetcode
2019
Conversations with God
Feelings is the language of the soul. If you want to know what’s true for you about something, look to how your’re feeling about.
Kafka In Spring
Enable Kafka listener annotated endpoints that are created under the covers by a AbstractListenerContainerFactory. To be used on Configuration classes as fol...
Terraform
Why Terraform
Kafka
Kafka
Mifid
FX Spot is not covered by the regulation, as it is not considered to be a financial instrument by ESMA, the European Union (EU) regulator. As FX is considere...
Foreign Exchange
currency pairs Direct ccy: means USD is part of currency pair Cross ccy: means ccy wihtout USD, so except NDF, the deal will be split to legs, both with...
2018
Seconds
nano seconds
Citrix receiver
Simple Binary Encoding (SBE)
Citrix receiver
“Cannot connect to remote desktop” with Citrix Receiver
Guice
A new type of Juice Put simply, Guice alleviates the need for factories and the use of new in your Java code. Think of Guice’s @Inject as the new new. You wi...
YAML
Key points All YAML files (regardless of their association with Ansible or not) can optionally begin with — and end with …. This is part of the YAML format a...
Distruptor
multithreading
Mockito
Feature
Protobuf
What are protocol buffers?
Sudo in a Nutshell
Sudo in a Nutshell Sudo (su “do”) allows a system administrator to give certain users (or groups of users) the ability to run some (or all) commands as root...
Zoo-keeper
ZK Motto the motto “ZooKeeper: Because Coordinating Distributed Systems is a Zoo.”
Presto DB
WHAT IS PRESTO?
Chronicle
Overview
Cucumber
Acceptance testing vs unit test It’s sometimes said that unit tests ensure you build the thing right, whereas acceptance tests ensure you build the right thi...
Scala
Scala String
akka framework of scala
philosophy The actor model adopts the philosophy that everything is an actor. This is similar to the everything is an object philosophy used by some object-o...
File Util in Apache Camel
FileUtil.class
Apache Camel
Camel’s message model In Camel, there are two abstractions for modeling messages, both of which we’ll cover in this section. org.apache.camel.Message—The ...
QuickFixJ
Settings
JXM
Exporting your beans to JMX The core class in Spring’s JMX framework is the MBeanExporter. This class is responsible for taking your Spring beans and registe...
Solace MQ
Solace PubSub+ It is a message broker that lets you establish event-driven interactions between applications and microservices across hybrid cloud environmen...
Apigee
App deployment, configuration management and orchestration - all from one system. Ansible is powerful IT automation that you can learn quickly.
Ansible
Ansible: What Is It Good For? Ansible is often described as a configuration management tool, and is typically mentioned in the same breath as Chef, Puppet, a...
flexbox
How Flexbox works — explained with big, colorful, animated gifs
Jboss tips
commands:
Locking and multithreading
Single Writer principle
KDB
KDB However kdb+ evaluates expressions right-to-left. There are no precedence rules. The reason commonly given for this behaviour is that it is a much simple...
Foreign Exchange
Foreign Exchange markets
Portactor
Better to use smart wait
Agile and SCRUM
Key concept In Scrum, a team is cross functional, meaning everyone is needed to take a feature from idea to implementation.
DevOps-Philosophy
:100:DevOps Model Defined
rxjs pipe in depth
https://stormforger.com/blog/2016/07/08/types-of-performance-testing/
How to setup nodejs to install package from intranet
Error of ‘ECONNRESET’ You may face error ECONNRESET from intranet, even appropriate proxy tools (e.g. cntlm) is running. The errors may looks like ```bash $ ...
Strategy-Of-Openshift-Releases
Release & Testing Strategy There are various methods for safely releasing changes to Production. Each team must select what is appropriate for their own ...
NodeJs Notes
commands to read files var lineReader = require(‘readline’).createInterface({ input: require(‘fs’).createReadStream(‘C:\dev\node\input\git_reset_files.tx...
Minium Viable Product
https://blog.leanstack.com/minimum-viable-product-mvp-7e280b0b9418
What is difference between declarations, providers and import in NgModule
What is difference between declarations, providers and import in NgModule
CORS :Cross-Origin Resource Sharing
Cross-Origin Request Sharing - CORS (A.K.A. Cross-Domain AJAX request) is an issue that most web developers might encounter, according to Same-Origin-Policy,...
ngrx
Why @Effects? In a simple ngrx/store project without ngrx/effects there is really no good place to put your async calls. Suppose a user clicks on a button or...
iOS programming
View A view is also a responder (UIView is a subclass of UIResponder). This means that a view is subject to user interactions, such as taps and swipes. Thus,...
2017
cloud computering
openshift vs openstack The shoft and direct answer is `OpenShift Origin can run on top of OpenStack. They are complementary projects that work well together....
cloud computering
Concepts Cloud computing is the on-demand demand delivery of compute database storage applications and other IT resources through a cloud services platform v...
Redux
whats @Effects You can almost think of your Effects as special kinds of reducer functions that are meant to be a place for you to put your async calls in suc...
reactive programing
The second advantage to a lazy subscription is that the observable doesn’t hold onto data by default. In the previous example, each event generated by the in...
common errors in NPM or node
code E503 code E503 when run npm install packages, e.g.
Container
The Docker project was responsible for popularizing container development in Linux systems. The original project defined a command and service (both named do...
promise vs observiable
The drawback of using Promises is that they’re unable to handle data sources that produce more than one value, like mouse movements or sequences of bytes in ...
Openshift tips
Commands bible
google analysis
How Page Value is calculated
JDK source
interface RandomAccess Marker interface used by List implementations to indicate that they support fast (generally constant time) random access. The primary ...
SSH SFTP
Secure FTP SFTP over FTP is the equivalant of HTTPS over HTTP, the security version
Setup WebSphere profiles and application in command line
Setup WebSphere profiles and application in command line
AWS Tips
After establishing a SSH session, you can install a default web server by executing sudo yum install httpd -y. To start the web server, type sudo service htt...
Oracle
ORA-12899: Value Too Large for Column
Spring notes
Spring Bean Life Cycle Callback Methods
Kindle notes
#《亿级流量网站架构核心技术》目录一览 TCP四层负载均衡 使用Hystrix实现隔离 基于Servlet3实现请求隔离 限流算法 令牌桶算法 漏桶算法 分布式限流 redis+lua实现 Nginx+Lua实现 使用sharding-jdbc分库分表 Disruptor+Redis...
Java JIT compiler
This is talking about Java JIT (Just-In-Time) compiler
Java Security Notes
Java Security well-behaved: programs should be prevent from consuming too much system resources
SeriableVersionUID
Noteworthy points about SeriableVersionUID in Java
R Language
s<-read.csv("C:/Users/xxx/dev/R/IRS/SHH_SCHISHG.csv") # aggregate s2<-table(s$Original.CP) s3<-as.data.frame(s2) # extract by Frequency ordered s3...
SSH and Cryptography
SFTP versus FTPS SS: Secure Shell An increasing number of our customers are looking to move away from standard FTP for transferring data, so we are ofte...
Eclipse notes
How do I remove a plug-in? Run Help > About Eclipse > Installation Details, select the software you no longer want and click Uninstall. (On Macintosh i...
Java JVM
Class loading subsystem
Maven-Notes
Maven philosophy “It is important to note that in the pom.xml file you specify the what and not the how. The pom.xml file can also serve as a documentatio...
Java New IO
Notes JDK 1.0 introduced rudimentary I/O facilities for accessing the file system (to create a directory, remove a file, or perform another task), accessi...
Network Protocols
Net Protocols
IT-Architect
SOA SOA is a set of design principles for building a suite of interoperable, flexible and reusable services based architecture. top-down and bottom-up a...
Algorithm
This page is about key points about Algorithm
Dead Lock
Concept
Java-Tricky-Tech-Questions.md
What is the difference between Serializable and Externalizable in Java? In earlier version of Java, reflection was very slow, and so serializaing large ob...
NavigableMap Misc
What is NavigableMap
Compare-In-Java
Concepts If you implement Comparable interface and override compareTo() method it must be consistent with equals() method i.e. for equal object by equals(...
Java Collections Misc
Difference between equals and deepEquals of Arrays in Java Arrays.equals() method does not compare recursively if an array contains another array on oth...
HashMap in JDK
Hashmap in JDK Some note worth points about hashmap Lookup process Step# 1: Quickly determine the bucket number in which this element may resid...
Java 8 Tips
This blog is listing key new features introduced in Java 8
Arbitrage vs Heading
What is the difference between arbitrage and hedging?
Java Enum Misc
Enum Misc
2016
Java GC notes
verbose:gc verbose:gc prints right after each gc collection and prints details about each generation memory details. Here is blog on how to read verbose gc
Hash Code Misc
contract of hashCode : Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consis...
Apache Tips
Apache
Angulary Misc
Dependency Injection Angular doesn’t automatically know how you want to create instances of your services or the injector to create your service. You must co...
Random number in java
ThreadLocalRandom, SecureRandm, java.util.Random, java.math.Random
Java new features
JDK Versions JDK 1.5 in 2005 JDK 1.6 in 2006 JDK 1.7 in 2011 JDK 1.8 in 2014 Sun之前风光无限，但是在2010年1月27号被Oracle收购。 在被Oracle收购后对外承诺要回到每2年一个realse的节奏。但是20...
用10几行代码自己写个人脸识别程序
用10几行代码自己写个人脸识别程序
Eslastic Search
Eslastic Search
JSON lines
JSON lines
Python Scraphy
Python Scraphy
Simpler chronicle of CI(Continuous Integration) “乱弹系列”之持续集成工具
引言 有句话说有人的地方就有江湖，同样，有江湖的地方就有恩怨。在软件行业历史长河（虽然相对于其他行业来说，软件行业的历史实在太短了，但是确是充满了智慧的碰撞也是十分的精彩）中有一些恩怨情愁，分分合合的小故事，比如类似的有，从一套代码发展出来后面由于合同到期就分道扬镳，然后各自发展成独门产品的Sybase DB和微...
Head First Blockchina 3
Hyperledger Fabric for Mortals
【原创】深入浅出区块链系统：第二章
使用Solidity创建以太坊(Ethereum)智能合约(Smart Contract)
How to customize Sublime syntax highlights
Reference Sublime Scope Naming Syntax Guide
浅谈软件单元测试中的“断言” (assert)，从石器时代进步到黄金时代。
大家都知道，在软件测试特别是在单元测试时,必用的一个功能就是“断言”（Assert)，可能有些人觉得不就一个Assert语句，没啥花头，也有很多人用起来也是懵懵懂懂，认为只要是Assert开头的方法，拿过来就用。一个偶然的机会跟人聊到此功能，觉得还是有必要在此整理一下如何使用以及对“断言”的理解。希望可以帮助大家...
Head First Blockchina 1
深入浅出区块链系统：第一章. what you should know about blockchain
Kubernetes 与 Docker Swarm的对比
Kubernetes 和Docker Swarm 可能是使用最广泛的工具，用于在集群环境中部署容器。但是这两个工具还是有很大的差别。
漫谈开发设计中的一些‘原则’及’设计哲学’
在开发设计中有一些常用原则或者潜规则，根据笔者的经验，这里稍微总结一下最最常用的，以飨读者。
http methods
RFC origion http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html#sec9.1.2)
Spark-vs-Storm
The stark difference among Spark and Storm. Although both are claimed to process the streaming data in real time. But Spark processes it as micro-batches; wh...
微服务
可以想像一下，之前的传统应用系统，像是一个大办公室里面，有各个部门，销售部，采购部，财务部。办一件事情效率比较高。但是也有一些弊端，首先，各部门都在一个房间里。
unmodifiableList, unmodifiableSet,unmodifiableMap
What’s it Returns an unmodifiable view of the specified set. This method allows modules to provide users with “read-only” access to internal sets. Query ope...
kibana, view layer of elasticsearch
What’s Kibana kibana is an open source data visualization plugin for Elasticsearch. It provides visualization capabilities on top of the content indexed on...
kibana, view layer of elasticsearch
What’s Kibana kibana is an open source data visualization plugin for Elasticsearch. It provides visualization capabilities on top of the content indexed on...
Anatomy of ThreadLocal
Design philosophies
iConnect
UI HTML5, AngularJS, BootStrap, REST API, JSON Backend Hadoop core (HDFS), Hive, HBase, MapReduce, Oozie, Pig, Solr
Business Analysis
Purpose of BA 带来一些商业价值（收益） 解决业务痛点
Something about RESTful architect
REST API must be hypertext driver Roy’s interview
Data Structure
Binary Tree A binary tree is a tree in which no node can have more than two children. A property of a binary tree that is sometimes important is that th...
Useful bookmarks
eBooks list of various books Node.js
heavy load web application
Common solutions
tips in as400 IBM Emulator
Toggle crosshair
Mysql operator to extract JSON
“Be the change you wish to see in the world.” - Mahatma Gandhi
equity trading
Difference between mutal funds and hedge funds
SQL
Differences between not in, not exists , and left join with null
HTTPS/2
concepts
Github page commands notes
404 error for customized domain (such as godday) 404 There is not a GitHub Pages site here. Go to github master branch for gitpages site, manually add CN...
RenMinBi International
RQFII RQFII stands for Renminbi Qualified Foreign Institutional Investor. RQFII was introduced in 2011 to allow qualified foreign institutional investors to ...
JavaScript tips
includes() vs some()
Docker Errors and Fixes
Docker Errors
Load Balancing
Concepts LVS means Linux Virtual Server, which is one Linux built-in component.
Python
(‘—–Unexpected error:’, <type ‘exceptions.TypeError’>) datetime.datetime.now()
Storage Management
RAID RAID is Reductant Array Independent Disk,
CI and CD
Concepts
XA Transactions in 2PC
Description
Setup Git in Mint Linux
How to setup Git in Mint Linux =================================================
Database sharding
DB sharding in YHD
Microservices vs. SOA
Microservice Services are organized around capabilities, e.g., user interface front-end, recommendation, logistics, billing, etc. Services are small in ...
Java Class Loader
Codecache The maximum size of the code cache is set via the -XX:ReservedCodeCacheSize=N flag (where N is the default just mentioned for the particular com...