Tutorial by Examples: ce

Sometimes it's useful to check if a field is present or absent on your JSON to avoid some JSONException on your code. To achieve that, use the JSONObject#has(String) or the method, like on the following example: Sample JSON { "name":"James" } Java code String jsonStr...

I won't explain what Any and FirstOrDefault does because there are already two good example about them. See Any and First, FirstOrDefault, Last, LastOrDefault, Single, and SingleOrDefault for more information. A pattern I often see in code which should be avoided is if (myEnumerable.Any(t=>t.Fo...

Since lots of beginners are confused about cloud hosting.I am writing this guide to walk through setting meteor on aws with ubuntu os. If you already have your instance running feel free to skip this step and go straight to installing meteor on aws. Login into AWS Console.Select EC2. Go to EC2 Dash...

Sometimes for organizational or other reasons it makes sense to have your top level resource return a sub-resource that would look like this. (Your sub-resource does not need to be an inner class) import javax.ws.rs.GET; import javax.ws.rs.Path; import javax.ws.rs.Produces; @Path("items&q...

If the size of your content is fixed, you can use absolute positioning to 50% with margin that reduces half of your content's width and height: HTML <div class="center"> Center vertically and horizontally </div> CSS .center { position: absolute; background...

A common thought pattern for inexperienced Java programmers is that exceptions are "a problem" or "a burden" and the best way to deal with this is catch them all1 as soon as possible. This leads to code like this: .... try { InputStream is = new FileInputStream(fileName);...

As a privileged user (root or sudo): Create scollector directory: mkdir /opt/scollector In the /opt/scollector directory, download the latest binary build from the bosun/scollector site, [http://bosun.org/scollector/][1] wget https://github.com/bosun-monitor/bosun/releases/download/"version...

An example of a class that contains a parcelable class inside: public class Repository implements Parcelable { private String name; private Owner owner; private boolean isPrivate; public Repository(String name, Owner owner, boolean isPrivate) { this.name = name; ...

You can define central config info's in a separate gradle include file Centralizing dependencies via "dependencies.gradle" file a stand alone properties file Versioning your builds via "version.properties" file or do it with root gradle.properties file the project structu...

Inline display elements, usually such as span or a, will include up to one white-space character before and after them in the document. In order to avoid very long lines in the markup (that are hard to read) and unintentional white-space (which affects formatting), the white-space can be commented o...

Most, but not all, C++ implementations support the #pragma once directive which ensures the file is only included once within a single compilation. It is not part of any ISO C++ standard. For example: // Foo.h #pragma once class Foo { }; While #pragma once avoids some problems associated w...

There are two common ways to list all processes on a system. Both list all processes running by all users, though they differ in the format they output (the reason for the differences are historical). ps -ef # lists all processes ps aux # lists all processes in alternative format (BSD) Thi...

VariableDetails$* / $@Function/script positional parameters (arguments). Expand as follows:$* and $@ are the same as $1 $2 ... (note that it generally makes no sense to leave those unquoted)"$*" is the same as "$1 $2 ..." 1 "$@" is the same as "$1" "$2&qu...

You can find description of the driver here. The quick example is: import psycopg2 db_host = 'postgres.server.com' db_port = '5432' db_un = 'user' db_pw = 'password' db_name = 'testdb' conn = psycopg2.connect("dbname={} host={} user={} password={}".format( ...

On systems that use the System-V style init scripts, such as RHEL/CentOS 6: service <service> start service <service> stop On systems using systemd, such as Ubuntu (Server and Desktop) >= 15.04, and RHEL/CentOS >= 7: systemctl <service> dnsmasq systemctl <service> ...

On systems that use the System-V style init scripts, such as RHEL/CentOS 6: service <service> status On systems using systemd, such as Ubuntu (Server and Desktop) >= 15.04, and RHEL/CentOS >= 7.0: systemctl status <service>

On systems using systemd, such as Fedora => 15, Ubuntu (Server and Desktop) >= 15.04, and RHEL/CentOS >= 7: systemctl status [servicename] ...where [servicename] is the service in question; for example, systemctl status sshd. This will show basic status information and any recent errors ...

You can place named arguments in any order you want. Sample Method: public static string Sample(string left, string right) { return string.Join("-",left,right); } Call Sample: Console.WriteLine (Sample(left:"A",right:"B")); Console.WriteLine (Sample(right...

What is an enter selection? In D3.js, when one binds data to DOM elements, three situations are possible: The number of elements and the number of data points are the same; There are more elements than data points; There are more data points than elements; In the situation #3, all the data ...

Subclassing also Subclasses Singleton Class class Example end Example.singleton_class #=> #<Class:Example> def Example.foo :example end class SubExample < Example end SubExample.foo #=> :example SubExample.singleton_class.superclass #=> #<Class:Example> ...