[This][1] actually sums it up pretty nicely.

API Levels generally mean that as a programmer, you can communicate with the devices&#39; built in functions and functionality. As the API level increases, functionality adds up (although some of it can get deprecated).

Choosing an API level for an application development should take at least two thing into account:

 1. [Current distribution][2] - How many devices can actually support my application, if it was developed for API level 9, it cannot run on API level 8 and below, then &quot;only&quot; around 60% of devices can run it (true to the date this post was made).
 2. Choosing a lower API level may support more devices but gain less functionality for your app. you may also work harder to achieve features you could&#39;ve easily gained if you chose higher API level.


Android API levels can be divided to five main groups (not scientific, but what the heck):

 1. Android 1.5 - 2.3 (Cupcake to Gingerbread) - (API levels 3-10) - Android made specifically for smartphones.
 2. Android 3.0 - 3.2 (Honeycomb) (API levels 11-13) - Android made for tablets.
 3. Android 4.0 - 4.4 (KitKat) - (API levels 14-19) - A big merge with tons of additional functionality, totally revamped Android version, for both phone and tablets. 
 4. Android 5.0 - 5.1 (Lollipop) - (API levels 21-22) - Material Design introduced.
 5. Android 6.0 - 6.… (Marshmallow) - (API levels 23-…) - Runtime Permissions,Apache HTTP Client Removed


  [1]: http://developer.android.com/guide/appendix/api-levels.html
  [2]: http://developer.android.com/resources/dashboard/platform-versions.html

API level is basically the Android version. Instead of using the Android version name (eg 2.0, 2.3, 3.0, etc) an integer number is used. This number is increased with each version. Android 1.6 is API Level 4, Android 2.0 is API Level 5, Android 2.0.1 is API Level 6, and so on.

An API is ready-made source code library. 

In Java for example APIs are a set of related classes and interfaces that come in packages. This picture illustrates the libraries included in the Java Standard Edition API. Packages are denoted by their color. 

![This pictures illustrates the libraries included in the Java Standard Edition API][1]

  [1]: http://i.stack.imgur.com/I6uUd.png

I am on a server that has  afresh install on RHEL 5.  I was able to install Apache and PHP just fine., but I am having serious trouble with my MySQL installation.  I tried the following:

    yum install mysql-server mysql 

And didn&#39;t get any errors or conflicts.  Then I tried to start mysql with the following commands:

    chkconfig --levels 235 mysqld on
    service mysqld start

And get `Timeout error occurred trying to start MySQL Daemon.`  

I checked my logs and see this error:

    [ERROR] Fatal error: Can&#39;t open and lock privilege tables: Table &#39;mysql.host&#39; doesn&#39;t exist

I&#39;m not sure where to go from here.

For reference I am using RHEL 5 and installed the latest versions of PHP 5 and Apache.


Fatal error: Can&#39;t open and lock privilege tables: Table &#39;mysql.host&#39; doesn&#39;t exist

Related: [Strings as variable references in R](https://stackoverflow.com/questions/3770589/strings-as-variable-references-in-r)  
Possibly related: [Concatenate expressions to subset a dataframe](https://stackoverflow.com/questions/5531238/concatenate-expressions-to-subset-a-dataframe)

---

I&#39;ve simplified the question per the comment request. Here goes with some example data.
    
    dat &lt;- data.frame(num=1:10,sq=(1:10)^2,cu=(1:10)^3)
    set1 &lt;- subset(dat,num&gt;5)
    set2 &lt;- subset(dat,num&lt;=5)
    
Now, I&#39;d like to make a bubble plot from these. I have a more complicated data set with 3+ colors and complicated subsets, but I do something like this:

    symbols(set1$sq,set1$cu,circles=set1$num,bg=&quot;red&quot;)
    symbols(set2$sq,set2$cu,circles=set2$num,bg=&quot;blue&quot;,add=T)

I&#39;d like to do a for loop like this:

    colors &lt;- c(&quot;red&quot;,&quot;blue&quot;)
    sets &lt;- c(&quot;set1&quot;,&quot;set2&quot;)
    vars &lt;- c(&quot;sq&quot;,&quot;cu&quot;,&quot;num&quot;)

    for (i in 1:length(sets)) {
       symbols(sets[[i]][,sq],sets[[i]][,cu],circles=sets[[i]][,num],
       bg=colors[[i]],add=T)
    }    

I know you can have a variable evaluated to specify the column (like `var=&quot;cu&quot;; set1[,var]`; I want to know how to get a variable to specify the data.frame itself (and another to evaluate the column).

---

**Update:** Ran across [this post](http://www.r-bloggers.com/converting-a-string-to-a-variable-name-on-the-fly-and-vice-versa-in-r/) on r-bloggers which has this example:

    x &lt;- 42
    eval(parse(text = &quot;x&quot;))
    [1] 42

I&#39;m able to do something like this now:

    eval(parse(text=paste(set[[1]],&quot;$&quot;,var1,sep=&quot;&quot;)))

In fiddling with this, I&#39;m finding it interesting that the following are not equivalent:

    vars &lt;- data.frame(&quot;var1&quot;,&quot;var2&quot;)
    eval(parse(text=paste(set[[1]],&quot;$&quot;,var1,sep=&quot;&quot;)))
    eval(parse(text=paste(set[[1]],&quot;[,vars[[1]]]&quot;,sep=&quot;&quot;)))

I actually have to do this:

    eval(parse(text=paste(set[[1]],&quot;[,as.character(vars[[1]])]&quot;,sep=&quot;&quot;)))

**Update2:** The above works to output values... but not in trying to plot. I can&#39;t do:

    for (i in 1:length(set)) {
    symbols(eval(parse(text=paste(set[[i]],&quot;$&quot;,var1,sep=&quot;&quot;))),
           eval(parse(text=paste(set[[i]],&quot;$&quot;,var2,sep=&quot;&quot;))),
           circles=paste(set[[i]],&quot;.&quot;,&quot;circles&quot;,sep=&quot;&quot;),
           fg=&quot;white&quot;,bg=colors[[i]],add=T)
    }

I get `invalid symbol coordinates`. I checked the class of set[[1]] and it&#39;s a factor. If I do `is.numeric(as.numeric(set[[1]]))` I get `TRUE`. Even if I add that above prior to the `eval` statement, I still get the error. Oddly, though, I can do this:

    set.xvars &lt;- as.numeric(eval(parse(text=paste(set[[i]],&quot;$&quot;,var1,sep=&quot;&quot;))))
    set.yvars &lt;- as.numeric(eval(parse(text=paste(set[[i]],&quot;$&quot;,var2,sep=&quot;&quot;))))
    symbols(xvars,yvars,circles=data$var3)

Why different behavior when stored as a variable vs. executed within the symbol function?

Getting strings recognized as variable names in R

I am wondering what exactly _API level_ means. I couldn&#39;t seem to find an answer by searching on Google.

Could anyone please explain what the term _API level_ means?

What does API level mean?

I am wondering what exactly API level means. I couldn't seem to find an answer by searching on Google.
Could anyone please explain what the term API level means?

I have an apk which I&#39;ve signed and uploaded to Android Market, and installed on my phone. I would like to debug this release apk (by means of Eclipse) whilst it is running on my phone. I have done this before (and remember it being with one of the Android development tools; perhaps Dalvik Debug Monitor) but unfortunately cannot remember how to do it and have been unable to find any articles online. Does anyone know how this can be done?

&gt; **Note:** I _have_ set `android:debuggable=&quot;true&quot;` in the manifest and have enabled USB Debugging on my phone.

How to debug apk signed for release?

I am trying to start up a `BroadcastReceiver` within a `Service`. What I am trying to do is have a background running `service` going that collects incoming text messages, and logs incoming phone calls. I figured the best way to go about this is to have a `service` running that incorporates a broadcast receiver that can catalog either. 

How do i go about doing this? I already have my service up and running.

Broadcast Receiver within a Service

My switch-case statement works perfectly fine yesterday. But when I run the code earlier this morning eclipse gave me an error underlining the case statements in color red and says: case expressions must be constant expression, it is constant I don&#39;t know what happened. Here&#39;s my code below:

    public void onClick(View src)
        {
        	switch(src.getId()) {
        	case R.id.playbtn:
    			checkwificonnection();
    			break;
    			
        	case R.id.stopbtn:
        		Log.d(TAG, &quot;onClick: stopping srvice&quot;);
        		Playbutton.setImageResource(R.drawable.playbtn1);
        		Playbutton.setVisibility(0); //visible
    			Stopbutton.setVisibility(4); //invisible
    			stopService(new Intent(RakistaRadio.this,myservice.class));
    			clearstatusbar();
    			timer.cancel();
    			Title.setText(&quot; &quot;);
    			Artist.setText(&quot; &quot;);
    			break;
    			
        	case R.id.btnmenu:
        		openOptionsMenu();
        		break;
        	}
        }

All R.id.int are all underlined in red.

switch case statement error: case expressions must be constant expression

What is the difference between [`START_STICKY`][1] and [`START_NOT_STICKY`][2] while implementing services in android? Could anyone point out to some standard examples.. ?


  [1]: http://developer.android.com/reference/android/app/Service.html#START_STICKY
  [2]: http://developer.android.com/reference/android/app/Service.html#START_NOT_STICKY

START_STICKY and START_NOT_STICKY

I am new to Android development and I want first to get the `Hello World` application running.
I am using Eclipse IDE and the Android 4.0.3 version 15 SDK. I copied everything from a tutorial site, but when I try to run the application on the `virtual device` I get this error:

    [2012-02-01 11:31:23 - Android_test] Installation error: INSTALL_FAILED_OLDER_SDK
    [2012-02-01 11:31:23 - Android_test] Please check logcat output for more details.
    [2012-02-01 11:31:23 - Android_test] Launch canceled!
Here is my class in the `com.maze.app` package:
    package com.maze.app;

    import android.app.Activity;
    import android.os.Bundle;
    import android.widget.TextView;

    public class HelloAndroid extends Activity{
	  @Override
	    public void onCreate(Bundle savedInstanceState) {
	        super.onCreate(savedInstanceState);
	        TextView tv = new TextView(this);
	        tv.setText(&quot;Hello, Android&quot;);
	        setContentView(tv);

	    }

    }

and the `AndroidManifest.xml`:

    &lt;?xml version=&quot;1.0&quot; encoding=&quot;utf-8&quot;?&gt;
    &lt;manifest xmlns:android=&quot;http://schemas.android.com/apk/res/android&quot;
    package=&quot;com.maze.app&quot;
    android:versionCode=&quot;1&quot;
    android:versionName=&quot;1.0&quot; &gt;

    &lt;uses-sdk android:minSdkVersion=&quot;15&quot; android:targetSdkVersion=&quot;@string/app_name&quot;/&gt;

    &lt;application
        android:icon=&quot;@drawable/ic_launcher&quot;
        android:label=&quot;@string/app_name&quot; &gt;
        &lt;activity android:name=&quot;HelloAndroid&quot; android:launchMode=&quot;standard&quot; android:enabled=&quot;true&quot;&gt;&lt;/activity&gt;
    &lt;/application&gt;

&lt;/manifest&gt;

Here is the configuration of the `Virtual Device`:

    Name: AndroidVD
    CPU/ABI: ARM(armeabi-v7a)
    Path: path\to\avd
    Target: Android 4.0.3(API level 15)
    Skin: WVGA800
    hw.lcd.density: 240
    hw.cpu.model: cortex-a8
    vm.heapSize: 48
    hw.ramSize:512

What is the problem?

EDIT:
The application is not running on the Virtual Device:
Here is what I get on LogCat(some of the lines):

    D/PackageManager(92): New package installed in /data/app/com.maze.app-2.apk
    D/dalvikvm(92): GC_CONCURRENT freed 660K, 9% free 11935K/12999K, paused 18ms+72ms
    I/ActivityManager(92): Force stopping package com.maze.app uid=10040
    D/BackupManagerService(92): Received broadcast Intent { act=android.intent.action.PACKAGE_REPLACED dat=package:com.maze.app flg=0x10000010 (has extras) }
    V/BackupManagerService(92): updatePackageParticipantsLocked: com.maze.app


Installation error: INSTALL_FAILED_OLDER_SDK

Bloomberg Open API [announced recently][1] - is it just the [Bloomberg SDK][2] which had been (limitedly) exposed to public for quite a while?

_My understanding_ is that Bloomberg SDK is possible to use only on the machine with a Bloomberg Terminal installed, but the recently announced Open API (which is syntactically the same) will be possible to use from any machine.

Is that correct? Are there any restrictions on the new API (say, delayed responses etc)? Just cannot believe they&#39;re giving away for free something that costed money - any clarifications are welcome!

---
**EDIT**: The above was probably not clear, so to rephrase: 

 1. I wonder if the newly announced Open API is syntactically the [Bloomberg SDK API][3] (or how they call it?) which has been available for years already
 1. assuming there are restrictions on using Open API on _any machine_ (comparing to using SDK from a machine with Bloomberg Terminal installed) - I wonder if those restrictions are specified in detail in some official Bloomberg doc. 

I can myself guess on both questions, but I thought I&#39;d rather ask :) 


  [1]: http://www.computerworlduk.com/news/it-business/3334375/bloomberg-market-data-api-made-public/
  [2]: http://www.bloomberg.com/professional/software_support/
  [3]: http://www.bloomberg.com/professional/software_support/

Bloomberg Open API

This is my first time trying to use the XMLRPC::Client library to interact with a remote API and I keep receiving this error:

    warning: peer certificate won&#39;t be verified in this SSL session

Searching around I&#39;ve found loads of people that have gotten that error. Usually it&#39;s with self-signed certificates and they just want it to go away, so they do something dirty like monkey patch the way XMLRPC::Client is opening it&#39;s http session.

I first assumed this was simply the client not caring whether the certificate was valid or not, so I continued my search and came across [this gem][1]. It simply forces verification of all SSL certificates and throws a hard error if it&#39;s not able too. This was exactly what I wanted. I included it, ran the code again and now I&#39;m getting this:

    OpenSSL:SSL::SSLError:
      SSL_connect returned=1 errno=0 state=SSLv3 read server certificate B:
      certificate verify failed

Of course! The certificate is bad! But I double check just to make sure with openssl&#39;s builtin s_client like so:

    openssl s_client -connect sub.example.com:443

and what do I get:

    CONNECTED(00000003)
    ---
    Certificate chain
    &lt;snip&gt;
    Verify return code: 0 (ok)

So now we get to my question. OpenSSL (the command line version) says the certificate is good. OpenSSL (the Ruby library) disagrees. All of my web browsers say the certificate is good.

A few additional details that might be of use. The certificate is a wildcard but is valid for the domain. The openssl s_client was run on the same machine seconds apart from the Ruby code. This is Ruby 1.8.7 p357 which is installed with RVM.

Does Ruby use something other than the CA bundle provided by the host OS? Is there a way to tell Ruby to use a specific CA bundle or the system one?


  [1]: https://github.com/jamesgolick/always_verify_ssl_certificates

Why is Ruby unable to verify an SSL certificate?

I&#39;d like to use [travis-ci][1] for one of my [projects][2].

The project is an API wrapper, so many of the tests rely on the use of secret API keys. To test locally, I just store them as environment variables. What&#39;s a safe way to use those keys on Travis?


  [1]: http://travis-ci.org/
  [2]: https://github.com/adelevie/parse-ruby-client

Using secret api keys on travis-ci

I&#39;ve read about oAuth, Amazon REST API, HTTP Basic/Digest and so on but can&#39;t get it all into &quot;single piece&quot;. This is probably the closest situation - https://stackoverflow.com/questions/3963877/creating-an-api-for-mobile-applications-authentication-and-authorization

I would like to built API-centric website - service. So (in the beginning) I would have an API in center and **website** (PHP + MySQL) would connect via **cURL**, **Android** and **iPhone** via their network interfaces. So 3 main clients - 3 API keys. And any other developer could also develop via API interface and they would get their own API key. API actions would be accepted/rejected based on userLevel status, if I&#39;m an admin I can delete anything etc., all other can manipulate only their local (account) data.

First, authorization - should I use oAuth + xAuth or my some-kind-of-my-own implemenation (see http://docs.amazonwebservices.com/AmazonCloudFront/latest/DeveloperGuide/RESTAuthentication.html?r=9197)? As I understand, on **Amazon service user is == API user (have API key)**. On my service I need to separate standard users/account (the one who registered on the website) and Developer Accounts (who should have their API key).

So I would firstly need to **authorize the API key** and then **Authenticate the user** itself. If I use Amazon&#39;s scheme to check developer&#39;s API keys (authorize their app), which sheme should I use for user authentication?

I read about getting a token via `api.example.org/auth` after (via **HTTPS**, HTTP Basic) posting my username and password and then forward it on every following request. How manage tokens if I&#39;m logged in simultaneously on **Android** and a **website**? What about man-in-the-middle-attack if I&#39;m using SSL only on first request (when username and password are transmitted) and just HTTP on every other? Isn&#39;t that a problem in this  example https://stackoverflow.com/questions/8562223/password-protecting-a-rest-service

REST API Authorization &amp; Authentication (web + mobile)

I&#39;ve scoured the web, but, alas, I just can&#39;t seem to get Rspec to correctly send content-type so I can test my JSON API. I&#39;m using the RABL gem for templates, Rails 3.0.11, and Ruby 1.9.2-p180.

My curl output, which works fine (should be a 401, I know):

    mrsnuggles:tmp gaahrdner$ curl -i -H &quot;Accept: application/json&quot; -X POST -d @bleh http://localhost:3000/applications
    HTTP/1.1 403 Forbidden 
    Content-Type: application/json; charset=utf-8
    Cache-Control: no-cache
    X-Ua-Compatible: IE=Edge
    X-Runtime: 0.561638
    Server: WEBrick/1.3.1 (Ruby/1.9.2/2011-02-18)
    Date: Tue, 06 Mar 2012 01:10:51 GMT
    Content-Length: 74
    Connection: Keep-Alive
    Set-Cookie: _session_id=8e8b73b5a6e5c95447aab13dafd59993; path=/; HttpOnly

    {&quot;status&quot;:&quot;error&quot;,&quot;message&quot;:&quot;You are not authorized to access this page.&quot;}

Sample from one of my test cases:

    describe ApplicationsController do
      render_views
      disconnect_sunspot

      let(:application) { Factory.create(:application) }

      subject { application }

      context &quot;JSON&quot; do

        describe &quot;creating a new application&quot; do

          context &quot;when not authorized&quot; do
            before do
              json = { :application =&gt; { :name =&gt; &quot;foo&quot;, :description =&gt; &quot;bar&quot; } }
              request.env[&#39;CONTENT_TYPE&#39;] = &#39;application/json&#39;
              request.env[&#39;RAW_POST_DATA&#39;] = json
              post :create
            end 
        
            it &quot;should not allow creation of an application&quot; do
              Application.count.should == 0
            end 

            it &quot;should respond with a 403&quot; do
              response.status.should eq(403)
            end 

            it &quot;should have a status and message key in the hash&quot; do
              JSON.parse(response.body)[&quot;status&quot;] == &quot;error&quot;
              JSON.parse(response.body)[&quot;message&quot;] =~ /authorized/
            end 
          end 

          context &quot;authorized&quot; do
          end 
        end
      end
    end

These tests never pass though, I always get redirected and my content-type is always `text/html`, regardless of how I seem to specify the type in my before block:

    # nope
    before do
      post :create, {}, { :format =&gt; :json }
    end

    # nada
    before do
      post :create, :format =&gt; Mime::JSON
    end

    # nuh uh
    before do
      request.env[&#39;ACCEPT&#39;] = &#39;application/json&#39;
      post :create, { :foo =&gt; :bar }
    end

Here is the rspec output:

    Failures:

      1) ApplicationsController JSON creating a new application when not authorized should respond with a 403
         Failure/Error: response.status.should eq(403)
       
           expected 403
                got 302
       
           (compared using ==)
         # ./spec/controllers/applications_controller_spec.rb:31:in `block (5 levels) in &lt;top (required)&gt;&#39;

      2) ApplicationsController JSON creating a new application when not authorized should have a status and message key in the hash
         Failure/Error: JSON.parse(response.body)[&quot;status&quot;] == &quot;errors&quot;
         JSON::ParserError:
           756: unexpected token at &#39;&lt;html&gt;&lt;body&gt;You are being &lt;a href=&quot;http://test.host/&quot;&gt;redirected&lt;/a&gt;.&lt;/body&gt;&lt;/html&gt;&#39;
         # ./spec/controllers/applications_controller_spec.rb:35:in `block (5 levels) in &lt;top (required)&gt;&#39;

As you can see I&#39;m getting the 302 redirect for the HTML format, even though I&#39;m trying to specify &#39;application/json&#39;.

Here is my `application_controller.rb`, with the rescue_from bit:

    class ApplicationController &lt; ActionController::Base

     rescue_from ActiveRecord::RecordNotFound, :with =&gt; :not_found

      protect_from_forgery
      helper_method :current_user
      helper_method :remove_dns_record

     rescue_from CanCan::AccessDenied do |exception|
        flash[:alert] = exception.message
        respond_to do |format|
          h = { :status =&gt; &quot;error&quot;, :message =&gt; exception.message }
          format.html { redirect_to root_url }
          format.json { render :json =&gt; h, :status =&gt; :forbidden }
          format.xml  { render :xml =&gt; h, :status =&gt; :forbidden }
        end 
      end

      private

      def not_found(exception)
        respond_to do |format|
          h = { :status =&gt; &quot;error&quot;, :message =&gt; exception.message }
          format.html { render :file =&gt; &quot;#{RAILS_ROOT}/public/404.html&quot;, :status =&gt; :not_found }
          format.json { render :json =&gt; h, :status =&gt; :not_found }
          format.xml  { render :xml =&gt; h, :status =&gt; :not_found }
        end
      end
    end

And also `applications_controller.rb`, specifically the &#39;create&#39; action which is what I&#39;m trying to test. It&#39;s fairly ugly at the moment because I&#39;m using `state_machine` and overriding the delete method.

      def create
        # this needs to be cleaned up and use accepts_attributes_for
        @application = Application.new(params[:application])
        @environments = params[:application][:environment_ids]
        @application.environment_ids&lt;&lt;@environments unless @environments.blank?

        if params[:site_bindings] == &quot;new&quot;
          @site = Site.new(:name =&gt; params[:application][:name])
          @environments.each do |e|
            @site.siteenvs &lt;&lt; Siteenv.new(:environment_id =&gt; e)
          end
        end

        if @site
          @application.sites &lt;&lt; @site
        end

        if @application.save
          if @site
            @site.siteenvs.each do |se|
              appenv = @application.appenvs.select {|e| e.environment_id == se.environment_id }
              se.appenv = appenv.first
              se.save
            end
          end
          flash[:success] = &quot;New application created.&quot;
          respond_with(@application, :location =&gt; @application)
        else
          render &#39;new&#39;
        end

        # super stinky :(
        @application.change_servers_on_appenvs(params[:servers]) unless params[:servers].blank?
        @application.save
      end

I&#39;ve looked at the source code here: https://github.com/rails/rails/blob/master/actionpack/lib/action_controller/metal/responder.rb, and it seems it should respond correctly, as well as a number of questions on stack overflow that seem to have similar issues and possible solutions, but none work for me.

What am I doing wrong?

Content Type	Original Author	Original Content on Stackoverflow
Question	Cemre Mengü	View Question on Stackoverflow
Solution 1 - Android	Rotemmiz	View Answer on Stackoverflow
Solution 2 - Android	aromero	View Answer on Stackoverflow
Solution 3 - Android	the_prole	View Answer on Stackoverflow

What does API level mean?

Android Problem Overview

Android Solutions

Solution 1 - Android

Solution 2 - Android

Solution 3 - Android

Getting strings recognized as variable names in R

Fatal error: Can't open and lock privilege tables: Table 'mysql.host' doesn't exist

Attributions