如何在java中反转数组
If you have a few years of experience in the Java ecosystem, 如何在 ExpertOption 中取款和存款 and you're interested in sharing that experience with the community (and getting 如何在 ExpertOption 中取款和存款 paid for your work of course), have a look at the "Write for Us" page. Cheers, Eugen
1. Overview
In this quick article, we'll show how we 如何在 ExpertOption 中取款和存款 can invert an array in Java.
We'll see a few different ways to do this using pure Java 8-based solutions – some of those mutate an 如何在 ExpertOption 中取款和存款 existing array and some create a new one.
Next, we'll look at two solutions using external libraries — one using Apache Commons Lang and one using 如何在 ExpertOption 中取款和存款 Google Guava.
2. Defining the Problem
The basic idea is to reverse the order of 如何在 ExpertOption 中取款和存款 the elements in the array. So, if given the array:
We'd like to get:
Let's see some ways we can do that.
3. Using a Traditional for Loop
The first way we might think about to invert an array 如何在 ExpertOption 中取款和存款 is by using a for loop:
As we can see, the code iterates through half of the array, changing the elements in symmetric positions.
We use a 如何在 ExpertOption 中取款和存款 temporary variable so that we don't lose the value of the current position of the array during the iteration.
4. Using Java 8 Stream API
We can also invert an array by using the Stream API:
Here we use the 如何在 ExpertOption 中取款和存款 method IntStream.range to generate a sequential stream of numbers. Then we map this sequence into array indexes in descending order.
5. Using Collections.reverse()
Let's 如何在 ExpertOption 中取款和存款 如何在 ExpertOption 中取款和存款 see how to invert an array using the Collections.reverse() method:
Compared with the previous examples, this is a more readable way to do the task.
6. Using Apache Commons Lang
Another option to invert an array is to use the 如何在 ExpertOption 中取款和存款 Apache Commons Lang library. To use it, we must first include the library as a dependency:
The latest version of Commons Lang can be found at Maven Central.
Let's use the ArrayUtils class to invert the array:
As we can see, this solution is quite simple.
7. Using Google Guava
One more option is to use the Google Guava library. Just as we did with the Commons Lang, we'll include the library as a dependency:
The latest version can be found at Maven Central.
Then, we can use the reverse method in Guava's Lists class to invert the array:
8. Conclusion
In this article, we looked at several different ways to invert an array in Java. We showed a few solutions using only core Java and two other solutions that use third-party libraries — Commons Lang and Guava.
All the code samples shown here can be found on GitHub — this is a Maven project, so it should be easy to import and run as it is.
如何在CentOS安裝配置OpenMeetings
OpenMeetings1、OpenMeetings[[email protected] ~]# yum -y groupinstall "GNOME Desktop 如何在 ExpertOption 中取款和存款 如何在 ExpertOption 中取款和存款 如何在 ExpertOption 中取款和存款 Environment"
[[email protected] ~]# yum groupinstall "'Office/Productivity"
[[email protected] ~]# yum install openoffice.org-headless
2、[[email protected] ~]# yum -y install freetype freetype-devel esvn fontconfig fontconfig-devel java-1.6.0-openjdk-devel libtiff libtiff-devel 如何在 ExpertOption 中取款和存款 libjpeg-devel libjpeg giflib giflib-devel libpaper libpaper-devel xml-commons-apis ibpng libpng-devel libxml2 libxml2-devel fftw3 git-svn fftw3-devel cairo cairo-devel flac flac-devel wavpack wavpack-devel libsndfile libsndfile-devel libmad libmad-devel yasm-devel yasm gcc 如何在 ExpertOption 中取款和存款 gcc-c++ mysql-server mysql-devel
3、[mysqld]
default-character-set=utf8
character-set-server=utf8
[client]
default-character-set=utf8
4、[[email protected] ~]# service mysqld start
[[email protected] 如何在 ExpertOption 中取款和存款 ~]# chkconfig mysqld on
[[email protected] ~]# mysqladmin -u root password tonyzhang
5、[[email protected] ~]# cd /usr/src
[[email protected] src]# wget http://ghostscript.com/releases/ghostscript-8.71.tar.gz
[[email protected] src]# tar zxvf ghostscript-8.71.tar.gz
[[email protected] src]# cd ghostscript-8.71
[[email protected] ghostscript-8.71]# ./configure --prefix=/usr
[[email protected] ghostscript-8.71]# mkdir obj
[[email protected] ghostscript-8.71]# mkdir bin
[[email protected] ghostscript-8.71]# make all
[[email protected] ghostscript-8.71]# make install
[[email protected] ~]# cd /usr/src
[[email protected] src]# wget 如何在 ExpertOption 中取款和存款 http://downloads.sourceforge.net/project/lame/lame/3.98.4/lame-3.98.4.tar.gz
[[email protected] src]# tar zxvf lame-3.98.4.tar.gz
[[email protected] src]# cd lame-3.98.4
[[email protected] lame-3.如何在 ExpertOption 中取款和存款 98.4]# ./configure --prefix=/usr
[[email protected] lame-3.98.4]# make all
[[email protected] lame-3.98.如何在 ExpertOption 中取款和存款 4]# make install
[[email protected] ~]# cd /usr/src
[[email protected] src]# wget http://www.swftools.org/swftools-0.9.1.tar.gz
[[email protected] src]# tar zxvf swftools-0.9.1.tar.gz
[[email protected] 如何在 ExpertOption 中取款和存款 src]# cd swftools-0.9.1
[[email protected] swftools-0.9.1]#./configure --prefix=/usr
[[email protected] swftools-0.如何在 ExpertOption 中取款和存款 9.1]#make all
[[email protected] swftools-0.9.1]#make install
[[email protected] ~]# cd /usr/src
[[email protected] src]# wget 如何在 ExpertOption 中取款和存款 http://acelnmp.googlecode.com/files/ImageMagick-6.6.4-10.tar.gz
[[email protected] src]# tar zxvf ImageMagick-6.如何在 ExpertOption 中取款和存款 6.4-10.tar.gz
[[email protected] src]# cd ImageMagick-6.6.4-10
[[email protected] ImageMagick-6.6.4-10]# ./configure --prefix=/usr
[[email protected] ImageMagick-6.6.4-10]# make all
[[email protected] ImageMagick-6.6.4-10]# make install
[[email protected] ~]# cd /usr/src
[[email protected] src]# svn checkout svn://svn.ffmpeg.org/ffmpeg/trunk ffmpeg
[[email protected] 如何在 ExpertOption 中取款和存款 src]# cd ffmpeg
[[email protected] ffmpeg]# ./configure --enable-libmp3lame --enable-postproc --enable-gpl --enable-pthreads --enable-avfilter --prefix=/usr
[[email protected] ffmpeg]# make all
[[email protected] ffmpeg]# make install
如何在Centos下安裝OpenVPN
3. 安裝的 OpenVPN 的版本: 2.1.rc15.(目前最新版 可在http://openvpn.net 上下載).
1. Windows XP SP2
二. OpenVPN 服務端安裝過程
2. 下載OpenVPN 2.1.rc15
tar zxvf lzo-2.03.tar.gz
tar zxvf openvpn-2.1_rc15.tar.gz
cp –rf /root/openvpn-2.1_rc15/ 如何在 ExpertOption 中取款和存款 /etc/openvpn
[[email protected] 2.0]# ./clean-all
[[email protected] 2.0]# ./build-ca
Generating a 1024 bit RSA private key
writing new private key to 'ca.key'
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite 如何在 ExpertOption 中取款和存款 a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
Country Name (2 letter code) [CN]:
State or Province Name (full name) [CN]:
Locality 如何在 ExpertOption 中取款和存款 Name (eg, city) [beijing]:
Organization Name (eg, company) [test]:beijing
Organizational Unit Name (eg, section) []:
Common Name (eg, your name or your server's hostname) [test CA]:
Email Address [[email protected]]:
[[email protected] 2.0]# ./build-key-server server
Generating a 1024 bit RSA 如何在 ExpertOption 中取款和存款 private key
writing new private key to 'server.key'
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are 如何在 ExpertOption 中取款和存款 about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
Country Name (2 letter code) [CN]:
State or Province Name (full name) [CN]:
Locality Name (eg, city) [beijing]:
Organization Name (eg, company) [test]:beijing
Organizational Unit Name (eg, section) []:
Common Name (eg, your name or your server's hostname) 如何在 ExpertOption 中取款和存款 [server]:
Email Address [[email protected]]:
Please enter the following 'extra' attributes
to be sent with 如何在 ExpertOption 中取款和存款 your certificate request
A challenge password []:
An optional company name []:
Using configuration from /etc/openvpn/easy-rsa/2.0/openssl.cnf
Check that the request matches the signature
The Subject's Distinguished Name 如何在 ExpertOption 中取款和存款 is as follows
Certificate is to be certified until Aug 12 14:55:28 2019 GMT (3650 days)
Sign the certificate? [y/n]:y
1 out of 1 certificate requests certified, commit? [y/n]y
Write out database with 1 new entries
Data Base Updated
[[email protected] 2.0]# ./build-key test
Generating a 1024 bit RSA private key
writing new private key to 'test.key'
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
Country Name (2 letter code) [CN]:
State or Province Name (full name) [CN]:
Locality Name (eg, city) [beijing]:
Organization 如何在 ExpertOption 中取款和存款 Name (eg, company) [test]:beijing
Organizational Unit Name (eg, section) []:
Common Name (eg, your 如何在 ExpertOption 中取款和存款 name or your server's hostname) [test]:
Email Address [[email protected]]:
Please enter 如何在 ExpertOption 中取款和存款 the following 'extra' attributes
to be sent with your certificate request
A challenge password []:
An 如何在 ExpertOption 中取款和存款 optional company name []:
Using configuration from /etc/openvpn/easy-rsa/2.0/openssl.cnf
Check that the request 如何在 ExpertOption 中取款和存款 matches the signature
The Subject's Distinguished Name is as follows
Certificate is to be certified until Aug 12 14:57:18 2019 GMT (3650 days)
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