1. Download Android studio
https://developer.android.com/sdk/installing/studio.html
2. Unpack and go to {studio}/bin
3. Run ./studio.sh to start Android studio
Monday, July 28, 2014
Thursday, July 24, 2014
Compare date strings in Java
To compare date strings:
package com.blogspot.javainpassion; import org.joda.time.format.DateTimeFormatter; import org.joda.time.format.ISODateTimeFormat; import java.text.ParseException; import java.text.SimpleDateFormat; import java.util.Date; public class DateApp { public static void main(String[] args) { try { SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd"); Date date1 = sdf.parse("2014-07-20"); Date date2 = sdf.parse("2014-04-25"); System.out.println(sdf.format(date1)); System.out.println(sdf.format(date2)); if (date1.after(date2)) { System.out.println("Date1 is after Date2"); } if (date1.before(date2)) { System.out.println("Date1 is before Date2"); } if (date1.equals(date2)) { System.out.println("Date1 is equal to Date2"); } // Joda-time library DateTimeFormatter dtf = ISODateTimeFormat.dateTimeNoMillis(); Long dateMillis1 = dtf.parseMillis("2014-07-20T00:00:00+02:00"); Long dateMillis2 = dtf.parseMillis("2014-07-25T00:00:00+02:00"); if (dateMillis1 < dateMillis2) { System.out.println("dateMillis1 is before dateMillis2"); } if (dateMillis1 > dateMillis2) { System.out.println("dateMillis1 is after dateMillis2"); } if (dateMillis1 == dateMillis2) { System.out.println("dateMillis1 is equal dateMillis2"); } } catch (ParseException ex) { ex.printStackTrace(); } } }
Wednesday, July 23, 2014
Sorting java collection
Java uses the Merge sorting algorithm to sort collection. We can sort java collections using the
java.util.Collections.sort() method. This method applies for List'collection type:
- List
- LinkedList
Natural Sorting:
//add elements to the listList list = new ArrayList();Collections.sort(list);
Sorting uses a Comparator
List<CustomObject> list = new ArrayList<CustomObject>(); Comparator<CustomObject> comparator = new Comparator<CustomObject>() { public int compare(CustomObject c1, CustomObject c2) { return c2.getYourField() - c1.getYourField(); // use your logic } }; Collections.sort(list, comparator);
Tuesday, July 15, 2014
The useful memory commands in Linux
- top
kiennguyen@kiennguyen-OptiPlex-790:~$ toptop - 13:21:33 up 2 days, 4:23, 14 users, load average: 0.09, 0.20, 0.20 Tasks: 278 total, 1 running, 277 sleeping, 0 stopped, 0 zombie %Cpu(s): 1.9 us, 0.7 sy, 0.0 ni, 96.1 id, 1.3 wa, 0.0 hi, 0.0 si, 0.0 st KiB Mem: 8054712 total, 7755744 used, 298968 free, 31392 buffers KiB Swap: 4070396 total, 805808 used, 3264588 free, 1204956 cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 2920 kiennguy 20 0 693m 88m 19m S 2.3 1.1 77:41.36 skype 3344 kiennguy 20 0 1339m 471m 21m S 2.0 6.0 40:55.79 firefox 13202 kiennguy 20 0 3618m 1.0g 18m S 1.3 12.8 16:32.04 java 19523 kiennguy 20 0 1041m 104m 25m S 1.3 1.3 0:26.08 chrome 3580 kiennguy 20 0 579m 23m 7936 S 0.7 0.3 1:58.67 gnome-terminal 15301 kiennguy 20 0 800m 21m 7908 S 0.7 0.3 1:07.96 chromium-browse 16530 kiennguy 20 0 1001m 149m 45m S 0.7 1.9 10:47.10 chrome 17010 kiennguy 20 0 2030m 320m 4936 S 0.7 4.1 2:15.19 java 1736 root 20 0 106m 952 568 S 0.3 0.0 4:37.82 ruby 2103 root 20 0 50056 3964 900 S 0.3 0.0 4:23.66 ruby1.8 10324 kiennguy 20 0 3932m 1.1g 3736 S 0.3 14.1 25:23.91 java 20346 kiennguy 20 0 1017m 95m 25m S 0.3 1.2 0:16.64 chrome
- vmstat
Virtual memory statistics
kiennguyen@kiennguyen-OptiPlex-790:~$ vmstat
procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu----
r b swpd free buff cache si so bi bo in cs us sy id wa
1 0 847924 240864 20220 1116116 1 2 17 34 46 53 3 1 95 1
- ulimit
kiennguyen@kiennguyen-OptiPlex-790:~$ ulimit -acore file size (blocks, -c) 0 data seg size (kbytes, -d) unlimited scheduling priority (-e) 0 file size (blocks, -f) unlimited pending signals (-i) 62776 max locked memory (kbytes, -l) 64 max memory size (kbytes, -m) unlimited open files (-n) 1024 pipe size (512 bytes, -p) 8 POSIX message queues (bytes, -q) 819200 real-time priority (-r) 0 stack size (kbytes, -s) 8192 cpu time (seconds, -t) unlimited max user processes (-u) 62776 virtual memory (kbytes, -v) unlimited file locks (-x) unlimited
- ps
kiennguyen@kiennguyen-OptiPlex-790:~$ ps aux | grep tomcat1000 10324 0.8 14.0 4027260 1131316 pts/11 Sl+ Jul14 25:28 /opt/devel/tools/jdk1.6.0_34/bin/java -Djava.util.logging.config.file=/opt/devel/tools/apache-tomcat-6.0.35/conf/logging.properties -Xshare:auto -Xms1024M -Xmx1G -XX:MaxPermSize=512M -Dexo.directory.base=/opt/devel -javaagent:/opt/devel/solr/newrelic/newrelic.jar -Dsolr.solr.home=/opt/devel/solr -Dsolr.data.dir=/opt/devel/solr/data -Dsolr.slave.url=http://localhost:8080/solr -Dsolr.master.url=http://localhost:8080/solr -Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=1024 -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djava.endorsed.dirs=/opt/devel/tools/apache-tomcat-6.0.35/endorsed -classpath /opt/devel/tools/apache-tomcat-6.0.35/bin/bootstrap.jar -Dcatalina.base=/opt/devel/tools/apache-tomcat-6.0.35 -Dcatalina.home=/opt/devel/tools/apache-tomcat-6.0.35 -Djava.io.tmpdir=/opt/devel/tools/apache-tomcat-6.0.35/temp org.apache.catalina.startup.Bootstrap start 1000 21485 0.0 0.0 10924 924 pts/25 S+ 13:32 0:00 grep tomcat
- kill
kiennguyen@kiennguyen-OptiPlex-790:~$ kill -9 19523
- iftop
Enable HTTPS in Play Framework
Play framework supported to serve HTTPS. We need to have a certificate
1. Create a self-signed SSL Certificate
Generate a private key:openssl genrsa -des3 -out server.key 1024
Generating RSA private key, 1024 bit long modulus
.....................++++++
.................................++++++
unable to write 'random state'
e is 65537 (0x10001)
Enter pass phrase for server.key:
Verifying - Enter pass phrase for server.key:
Generate a CSR
openssl req -new -key server.key -out server.csr
Enter pass phrase for server.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) [AU]:VN
State or Province Name (full name) [Some-State]:HaNoi
Locality Name (eg, city) []:HaNoi
Organization Name (eg, company) [Internet Widgits Pty Ltd]:Niteco Ltd
Organizational Unit Name (eg, section) []:Software technology
Common Name (e.g. server FQDN or YOUR name) []:niteco.se
Email Address []:nguyenanhkien2a at gmail dot com
Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:123456
An optional company name []:
Remove passphase from key
cp server.key server.key.org
openssl rsa -in server.key.org -out server.key
openssl rsa -in server.key.org -out server.key
Enter pass phrase for server.key.org:
writing RSA key
openssl x509 -req -days 365 -in server.csr -signkey server.key -out server.crt
Signature ok
subject=/C=VN/ST=HaNoi/L=HaNoi/O=Niteco Ltd/OU=Software technology/CN=niteco.se/emailAddress=nguyenanhkien2a at gmail dot com
Getting Private key
2. Add the certificate in your configuration
Add the configuration below into file {APP}/conf/application.confhttps.port=9443
certificate.key.file=conf/server.key
certificate.file=conf/server.crt
certificate.password=Asdfg@123456
trustmanager.algorithm=JKS
Note: We must locate the server.crt and server.key in the application conf folder. Play framework cannot read from outsite folder
3. Restart your play application
Basic git commands
- git init
To create a new Git repository
git init
git init <directory>
git init <directory>
- git clone
Clone the repository in local machine
git clone <repo>
git clone <repo> <directory>
- git config
Define author name, email for commits
git config user.name <name>
git config --global user.name <name>
git config --global user.email <email>
Example:
git config user.name kien.nguyen
git config --global user.name kien.nguyen
git config --global user.email nguyenanhkien2a@gmail.com
- git diff
View a change in details (line by line)
git diff <file>
git diff --cache
git diff --base <file>
git diff <source_branch> <target_branch>
- git status
List files in staged, unstaged, untracked.
git status
- git reset
Clear all local changes
git reset
git reset <file>
git reset --hard
git reset <commit>
git reset --hard <commit>
- git add
Add a change to staging area, staging area will be used into commit
git add <file>
git add <directory>
git add .
git add *
- git commit
Commit your changes in staging area to HEAD in local working repository
git commit -m "your message"
Commit all your changes in staging/unstaging to HEAD in local working reposiroty
git commit -a -m "your message"
Edit the last commit
git commit --amend
- git log
View committed snapshots
git log
git log -n <number>
git log --oneline
git log --stat
git log <file>
git log -p
git log --author="<pattern>"
git log --grep="<pattern>"
- git fetch
Fetch latest changes from remote repository
git fetch
git fetch origin
- git pull
Fetch and update commits from remote repository into local working repository
git pull
- git push
Push local working branch to remote repository
git push
git push origin <remote_branch>
Example:
git push origin master
- git branch
List all branches in your local repository
git branch
- git checkout
Checkout a branch to working tree
git checkout <branch>
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