The default value of a union corresponds to the first schema of the union ([Source][1]). Your union is defined as `[&quot;long&quot;, &quot;null&quot;]` therefor the default value must be a long number. `null` is not a long number that is why you are getting an error.

If you still want to define `null` as a default value then put null schema first, i.e. change the union to `[&quot;null&quot;, &quot;long&quot;]` instead.


  [1]: https://groups.google.com/a/cloudera.org/d/msg/cdk-dev/Xgo5YKEcQ1Q/VkyWP2gnOEMJ

Its a **bug** at Avro&#39;s end which is marked as `Not A Problem` .
You need to add default attribute to mention default value.

    {&quot;name&quot;: &quot;xxx&quot;, &quot;type&quot;: [&quot;null&quot;, &quot;boolean&quot;], &quot;default&quot;: null}

Please refer [AVRO-1803][1].


  [1]: https://issues.apache.org/jira/browse/AVRO-1803

You must provide `&quot;default&quot;: null` not `&quot;default&quot;: &quot;null&quot;` in the schema to get the builder method working

I think the problem is that you are using builder, 

According to the [documentation][1] of the Java API:

&gt; using a builder requires setting all fields, even if they are null




  [1]: https://avro.apache.org/docs/1.8.1/gettingstartedjava.html#Creating+Users

I have a stored procedure that takes in two parameters. I can execute it successfully in Server Management Studio. It shows me the results which are as I expect. However it also returns a Return Value.

It has added this line,

     SELECT &#39;Return Value&#39; = @return_value

I would like the stored procedure to return the table it shows me in the results not the return value as I am calling this stored procedure from MATLAB and all it returns is true or false.

Do I need to specify in my stored procedure what it should return? If so how do I specify a table of 4 columns (varchar(10), float, float, float)?

SQL server stored procedure return a table

There seems to be a change in the google spreadsheet publishing options. It is no longer possible to publish to the web as csv or tab file ([see this recent post][1]). Thus the usual way to use RCurl to import data into R from a google spreadsheed does not work anymore:

    require(RCurl)
    u &lt;- &quot;https://docs.google.com/spreadsheet/pub?hl=en_GB&amp;hl=en_GB&amp;key=0AmFzIcfgCzGFdHQ0eEU0MWZWV200RjgtTXVMY1NoQVE&amp;single=true&amp;gid=4&amp;output=csv&quot;
    tc &lt;- getURL(u, ssl.verifypeer=FALSE)
    net &lt;- read.csv(textConnection(tc))


Does anyone have a work-around?


  [1]: https://stackoverflow.com/questions/21189665/new-google-spreadsheets-publish-limitation

Importing data into R from google spreadsheet

I am running into some issues setting up default values for Avro fields. I have a simple schema as given below:

**data.avsc:**

    {
     &quot;namespace&quot;:&quot;test&quot;,
     &quot;type&quot;:&quot;record&quot;,
     &quot;name&quot;:&quot;Data&quot;,
     &quot;fields&quot;:[
        { &quot;name&quot;: &quot;id&quot;, &quot;type&quot;: [ &quot;long&quot;, &quot;null&quot; ] },
        { &quot;name&quot;: &quot;value&quot;, &quot;type&quot;: [ &quot;string&quot;, &quot;null&quot; ] },
        { &quot;name&quot;: &quot;raw&quot;, &quot;type&quot;: [ &quot;bytes&quot;, &quot;null&quot; ] }
     ]
    }

I am using the *avro-maven-plugin v1.7.6* to generate the Java model.

When I create an instance of the model using:
`Data data = Data.newBuilder().build();`, it fails with an exception: 

&gt; org.apache.avro.AvroRuntimeException:
&gt; org.apache.avro.AvroRuntimeException: Field id type:UNION pos:0 not
&gt; set and has no default value.

But if I specify the &quot;default&quot; property,

    { &quot;name&quot;: &quot;id&quot;, &quot;type&quot;: [ &quot;long&quot;, &quot;null&quot; ], &quot;default&quot;: &quot;null&quot; },

 I do not get this error. I read in the documentation that first schema in the union becomes the default schema. So my question is, why do I still need to specify the &quot;default&quot; property? How else do I make a field optional?

And if I do need to specify the default values, how does that work for a union; do I need to specify default values for each schema in the union and how does that work in terms of order/syntax?

Thanks.

Avro field default values

I am running into some issues setting up default values for Avro fields. I have a simple schema as given below:
data.avsc:
<pre><code class="hljs language-json">{
 "namespace":"test",
 "type":"record",
 "name":"Data",
 "fields":[
 { "name": "id", "type": [ "long", "null" ] },
 { "name": "value", "type": [ "string", "null" ] },
 { "name": "raw", "type": [ "bytes", "null" ] }
 ]
}
</code></pre>
I am using the avro-maven-plugin v1.7.6 to generate the Java model.
When I create an instance of the model using:
<code>Data data = Data.newBuilder().build();</code>, it fails with an exception:
> org.apache.avro.AvroRuntimeException:
> org.apache.avro.AvroRuntimeException: Field id type:UNION pos:0 not
> set and has no default value.
But if I specify the "default" property,
<pre><code class="hljs language-json">{ "name": "id", "type": [ "long", "null" ], "default": "null" },
</code></pre>
I do not get this error. I read in the documentation that first schema in the union becomes the default schema. So my question is, why do I still need to specify the "default" property? How else do I make a field optional?
And if I do need to specify the default values, how does that work for a union; do I need to specify default values for each schema in the union and how does that work in terms of order/syntax?
Thanks.

How to get first element that matches a criteria in a stream? I&#39;ve tried this but doesn&#39;t work

    this.stops.stream().filter(Stop s-&gt; s.getStation().getName().equals(name));

That criteria is not working, the filter method is invoked in an other class than Stop.


    public class Train {

	private final String name;
	private final SortedSet&lt;Stop&gt; stops;

	public Train(String name) {
		this.name = name;
		this.stops = new TreeSet&lt;Stop&gt;();
	}

	public void addStop(Stop stop) {
		this.stops.add(stop);
	}

	public Stop getFirstStation() {
		return this.getStops().first();
	}

	public Stop getLastStation() {
		return this.getStops().last();
	}

	public SortedSet&lt;Stop&gt; getStops() {
		return stops;
	}

	public SortedSet&lt;Stop&gt; getStopsAfter(String name) {


		// return this.stops.subSet(, toElement);
		return null;
	}
    }
    
    
    import java.util.ArrayList;
    import java.util.List;
    
    public class Station {
	private final String name;
	private final List&lt;Stop&gt; stops;

	public Station(String name) {
		this.name = name;
		this.stops = new ArrayList&lt;Stop&gt;();

	}

	public String getName() {
		return name;
	}

    }






Fetch first element of stream matching the criteria

How can I **programmatically shutdown** a **Spring Boot** application **without terminating the VM**?

In other works, what is the opposite of

    new SpringApplication(Main.class).run(args);

Programmatically shut down Spring Boot application

I&#39;m wondering if putting a _return_ statement inside a _try-with-resources_ block prevents the resource to be automatically closed.

    try(Connection conn = ...) {
        return conn.createStatement().execute(&quot;...&quot;);
    }

If I write something like this will the _Connection_ be closed? In the Oracle documentation it is stated that:

&gt;  The try-with-resources statement ensures that each resource is closed at the end of the statement.

What happens if the end of the statement is never reached because of a return statement?

Try-with-resources and return statements in java

I have a 2&amp;nbsp;GB file (`iputfile.txt`) in which every line in the file is a word, just like:

    apple
    red
    beautiful
    smell
    spark
    input

I need to write a program to read every word in the file and print the word count. I wrote it using Java and C++, but the result is surprising: Java runs 2.3 times faster than C++. My code are as follows:

C++:

    int main() {
        struct timespec ts, te;
        double cost;
        clock_gettime(CLOCK_REALTIME, &amp;ts);

        ifstream fin(&quot;inputfile.txt&quot;);
        string word;
        int count = 0;
        while(fin &gt;&gt; word) {
            count++;
        }
        cout &lt;&lt; count &lt;&lt; endl;

        clock_gettime(CLOCK_REALTIME, &amp;te);
        cost = te.tv_sec - ts.tv_sec + (double)(te.tv_nsec-ts.tv_nsec)/NANO;
        printf(&quot;Run time: %-15.10f s\n&quot;, cost);

        return 0;
    }

Output:

    5e+08
    Run time: 69.311 s

Java:

     public static void main(String[] args) throws Exception {

        long startTime = System.currentTimeMillis();

        FileReader reader = new FileReader(&quot;inputfile.txt&quot;);
        BufferedReader br = new BufferedReader(reader);
        String str = null;
        int count = 0;
        while((str = br.readLine()) != null) {
            count++;
        }
        System.out.println(count);

        long endTime = System.currentTimeMillis();
        System.out.println(&quot;Run time : &quot; + (endTime - startTime)/1000 + &quot;s&quot;);
    }

Output:

    5.0E8
    Run time: 29 s

Why is Java faster than C++ in this situation, and how do I improve the performance of C++?


Why does Java read a big file faster than C++?

Does someone know where I can find the document by Oracle which describes Java code conventions?

This URL is not available anymore, for that reason I created new question for this topic.

http://www.oracle.com/technetwork/java/codeconv-138413.html 

Oracle Java code conventions

What is the difference between **Nexus** and **Maven**?

What is a basic scenario of usage only **Maven**? What about a scenario considering only **Nexus**? And how it looks when I want to use both?

What is the difference between Nexus and Maven?

I am using maven with the _jacoco_ plugin to generate code coverage metrics. I am having some difficulty in configuring the _surefire_ plugin with the java options required by the _jacoco_ plugin. I&#39;ve seen some answers about this already on Stack Overflow but something is not working for me.

I have a multi-module project, and one of my modules configures the _surefire_ plugin as follows:

`foo/pom.xml`:

    &lt;plugins&gt;
      &lt;plugin&gt;
        &lt;groupId&gt;org.apache.maven.plugins&lt;/groupId&gt;
        &lt;artifactId&gt;maven-surefire-plugin&lt;/artifactId&gt;
        &lt;configuration&gt;
          &lt;argLine&gt;-XX:MaxPermSize=512m&lt;/argLine&gt;
        &lt;/configuration&gt;
      &lt;/plugin&gt;
    &lt;/plugins&gt;

This works as expected.

Now I want to incorporate jacoco to get code coverage metrics, so I added a _CodeCoverage_ profile that handles all the jacoco configuration:

`parent/pom.xml`:

    &lt;profile&gt;
      &lt;id&gt;CodeCoverage&lt;/id&gt;
      &lt;build&gt;
        &lt;pluginManagement&gt;
          &lt;plugins&gt;
            &lt;plugin&gt;
              &lt;groupId&gt;org.jacoco&lt;/groupId&gt;
              &lt;artifactId&gt;jacoco-maven-plugin&lt;/artifactId&gt;
              &lt;executions&gt;
                &lt;execution&gt;
                  &lt;id&gt;jacoco-initialize&lt;/id&gt;
                  &lt;goals&gt;&lt;goal&gt;prepare-agent&lt;/goal&gt;&lt;/goals&gt;
                  &lt;configuration&gt;
                    &lt;propertyName&gt;surefire.argLine&lt;/propertyName&gt;
                  &lt;/configuration&gt;
                  ...
                &lt;/execution&gt;
              &lt;executions&gt; 
            &lt;/plugin&gt;
          &lt;/plugins&gt;
        &lt;/pluginManagement&gt;
      &lt;/build&gt;   
    &lt;/profile&gt;

It is seen here that if the _CodeCoverage_ profile is specified, then the _jacoco_ plugin is configured to use the `surefire.argLine` property, and that property is used to configure the `argLine` for the _surefire_ plugin.

I then updated the _pom.xml_ file for the _foo_ module to use the `surefire.argLine` property generated by the _jacoco_ plugin:

`foo/pom.xml`:

    &lt;plugins&gt;
      &lt;plugin&gt;
        &lt;groupId&gt;org.apache.maven.plugins&lt;/groupId&gt;
        &lt;artifactId&gt;maven-surefire-plugin&lt;/artifactId&gt;
        &lt;configuration&gt;
          &lt;argLine&gt;${surefire.argLine} -XX:MaxPermSize=512m&lt;/argLine&gt;
        &lt;/configuration&gt;
      &lt;/plugin&gt;
    &lt;/plugins&gt;

This approach is specified in the _jacoco_ plugin documentation (see [1]).

When I build the _foo_ module with the _CodeCoverage_ profile, I see the following:

    [foo] $ mvn clean install -X -PCodeCoverage
    ...
    [INFO] --- jacoco-maven-plugin:0.7.0.201403182114:prepare-agent (jacoco-initialize) @ foo ---
    [INFO] surefire.argLine set to -javaagent:...\\org.jacoco.agent\\0.7.0.201403182114\\org.jacoco.agent-0.7.0.201403182114-runtime.jar=destfile=...\foo\\\target\\coverage-reports\\jacoco-ut.exec
    ...
    [DEBUG] Configuring mojo &#39;org.apache.maven.plugins:maven-surefire-plugin:2.13:test&#39; with basic configurator --&gt;
    [DEBUG]   (s) argLine = -javaagent:...\\org.jacoco.agent\\0.7.0.201403182114\\org.jacoco.agent-0.7.0.201403182114-runtime.jar=destfile=...\\foo\\target\\coverage-reports\\jacoco-ut.exec -XX:MaxPermSize=512m
    ...
    [INFO] --- jacoco-maven-plugin:0.7.0.201403182114:report (jacoco-site) @ foo ---
    [INFO] Analyzed bundle &#39;Foo&#39; with 59 classes`

So the _jacoco_ plugin is executed, a `surefire.argLine` property is created, the `argLine` for the _surefire_ plugin uses the `surefire.argLine` property and the local `MaxPermSize` argument, and a `target\code-coverage\jacoc-ut-exec` file is generated, as expected.

However, if I do not use the _CodeCoverage_ profile, then I get an error, because the `${surefire.argLine}` property (used in `foo/pom.xml`) is not created by the _jacoco_ plugin, and is not defined anywhere:

    [foo] $ mvn clean install -X
    ...
    [DEBUG] Configuring mojo &#39;org.apache.maven.plugins:maven-surefire-plugin:2.13:test&#39; with basic configurator --&gt;
    [DEBUG]   (s) argLine = ${surefire.argLine} -XX:MaxPermSize=512m
    ...
    Error: Could not find or load main class ${surefire.argLine}`

Sinec the _jacoco_ plugin was not invoked, there&#39;s no `surefire.argLine` property created, hence the error. 

So, I go back to the `parent/pom.xml` and create this property, with no initial value:

`parent/pom.xml`:

    &lt;properties&gt;
      &lt;surefire.argLine&gt;&lt;/surefire.argLine&gt;
    &lt;/properties&gt;

Now when I build the _foo_ module without using the _CodeCoverage_ profile, I get no errors:

    [foo] $ mvn clean install -X
    ...
    [DEBUG] Configuring mojo &#39;org.apache.maven.plugins:maven-surefire-plugin:2.13:test&#39; with basic configurator --&gt;
    [DEBUG]   (s) argLine =  -XX:MaxPermSize=512m
    ...
    [INFO] BUILD SUCCESS`

The _surefire_ argline is now correct (using the empty `surefire.argLine` property) and there is no `target\code-coverage` directory, as expected.

So now I go back to generating code metrics, using the _CodeCoverage_ profile:

    [foo] $ mvn clean install -X -PCodeCoverage
    ...
    [INFO] --- jacoco-maven-plugin:0.7.0.201403182114:prepare-agent (jacoco-initialize) @ foo ---
    [INFO] surefire.argLine set to -javaagent:...\\org.jacoco.agent\\0.7.0.201403182114\\org.jacoco.agent-0.7.0.201403182114-runtime.jar=destfile=...\\foo\\target\\coverage-reports\\jacoco-ut.exec
    ...
    [DEBUG] Configuring mojo &#39;org.apache.maven.plugins:maven-surefire-plugin:2.13:test&#39; with basic configurator --&gt;
    [DEBUG]   (s) argLine =  -XX:MaxPermSize=512m
    ...
    [INFO] --- jacoco-maven-plugin:0.7.0.201403182114:report (jacoco-site) @ foo ---
    [INFO] Skipping JaCoCo execution due to missing execution data file:...\foo\target\coverage-reports\jacoco-ut.exec

It can be observed here that the _jacoco_ plugin is invoked and sets the `surefire.argLine` property, but the `surefire.argLine` property with the empty value defined in the `parent/pom.xml` file is actually used to create the argline for the _surefire_ plugin.

As a result, there is no `jacoco-ut.exec` file, and no `target\code-coverage` directory, when I use the _CodeCoverage_ profile.

I&#39;m not sure what I am doing wrong here. I&#39;m declaring an `argLine` property as suggested by the _jacoco_ documentation, and using it whenever a _surefire_ plugin needs to specify additional argument. Other answers on Stack Overflow suggest creating a property with the same name as the _jacoco_ argLine property to handle the case when _jacoco_ is not invoked.

Any suggestions?


**edit** 

Maybe one solution is to explicitly declare the `surefire.argLine` property in the _CodeCoverage_ profile, and forget about using the `argLine` of the _jacoco_ plugin:

    &lt;profile&gt;
      &lt;id&gt;CodeCoverage&lt;/id&gt;
      &lt;properties&gt;
        &lt;surefire.argLine&gt;-javaagent:${jacoco.agent.jar}=destfile=${jacoco.report.path}&lt;/surefire.argLine&gt;
      &lt;/properties&gt;
      &lt;build&gt;
        &lt;plugins&gt;
          &lt;plugin&gt;
            &lt;groupId&gt;org.jacoco&lt;/groupId&gt;
            &lt;artifactId&gt;jacoco-maven-plugin&lt;/artifactId&gt;
            &lt;executions&gt;
              &lt;execution&gt;
                &lt;id&gt;jacoco-initialize&lt;/id&gt;
                &lt;goals&gt;
                  &lt;goal&gt;prepare-agent&lt;/goal&gt;
                &lt;/goals&gt;
                &lt;!-- no longer specifying &#39;argLine&#39; for jacoco plugin ... --&gt;  
              &lt;/execution&gt;
            &lt;executions&gt; 
          &lt;/plugin&gt;
          &lt;plugin&gt;
            &lt;groupId&gt;org.apache.maven.plugins&lt;/groupId&gt;
            &lt;artifactId&gt;maven-surefire-plugin&lt;/artifactId&gt;
            &lt;configuration&gt;
              &lt;!-- ... instead the arg line is configured explicitly for surefire plugin. --&gt;
              &lt;argLine&gt;${surefire.argLine}&lt;/argLine&gt;
            &lt;/configuration&gt;
          &lt;/plugin&gt;
        &lt;/plugins&gt;
      &lt;/plugin&gt;
    &lt;/build&gt;
  &lt;/profile&gt;

This will create the _surefire.argLine_ property to use the java agent required by the _jacoco_ plugin, and configure the _surefire_ plugin to use that property for its JVM args. The _jacoco_ plugin will now create a _argLine_ property, but this will be ignored. It&#39;s not an elegant solution (since I&#39;m making assumptions about how the _jacoco_ plugin works, and this may change in a future version).

**edit** 

The `jacoco.agent.jar` property must also be set, by pointing to its location in the local repository (not sure if this is robust) or by using the _dependency_ plugin to copy the _jacoco_ agent jar to the local build directory:

    &lt;profile&gt;
      &lt;id&gt;CodeCoverage&lt;/id&gt;
      &lt;properties&gt;
        &lt;jacoco.agent.jar&gt;${project.build.directory}/jacoco-agent.jar&lt;/jacoco.agent.jar&gt;
        ...
      &lt;/project&gt;
      &lt;build&gt;
        ...
        &lt;plugins&gt;
          &lt;plugin&gt;
            &lt;groupId&gt;org.apache.maven.plugins&lt;/groupId&gt;
            &lt;artifactId&gt;maven-dependency-plugin&lt;/artifactId&gt;
            &lt;executions&gt;
              &lt;execution&gt;
                &lt;id&gt;download-jacoco-agent&lt;/id&gt;
                &lt;phase&gt;process-test-resources&lt;/phase&gt;
                &lt;goals&gt;
                  &lt;goal&gt;copy&lt;/goal&gt;
                &lt;/goals&gt;
                &lt;configuration&gt;
                  &lt;artifactItems&gt;
                    &lt;artifactItem&gt;
                      &lt;groupId&gt;org.jacoco&lt;/groupId&gt;
                      &lt;artifactId&gt;org.jacoco.agent&lt;/artifactId&gt;
                      &lt;version&gt;${jacoco.version}&lt;/version&gt;
                      &lt;classifier&gt;runtime&lt;/classifier&gt;
                      &lt;outputDirectory&gt;${project.build.directory}&lt;/outputDirectory&gt;
                      &lt;destFileName&gt;jacoco-agent.jar&lt;/destFileName&gt;
                    &lt;/artifactItem&gt;
                  &lt;/artifactItems&gt;
                &lt;/configuration&gt;
              &lt;/execution&gt;
            &lt;/executions&gt;
          &lt;/plugin&gt;
        &lt;/plugins&gt;
      &lt;/build&gt;
    &lt;/profile&gt;

**edit** 

Not sure if using the _dependency_ plugin is the right approach, or pointing to the jacoco agent artifact in the local repository:

    &lt;profile&gt;
      &lt;id&gt;CodeCoverage&lt;/id&gt;
      &lt;properties&gt;
        &lt;jacoco.agent.jar&gt;${settings.localRepository}/org/jacoco/org.jacoco.agent/${jacoco.version}/org.jacoco.agent-${jacoco.version}-runtime.jar&lt;/jacoco.agent.jar&gt;
      &lt;/properties&gt;
      ...
    &lt;/profile&gt;
   
This is simpler, and does not require copying an artifact to the local build directory, but is fragile: changes in the repository layout will break this.

[1] http://www.eclemma.org/jacoco/trunk/doc/prepare-agent-mojo.html

Cannot use jacoco JVM args and surefire JVM args together in maven

    Execution default of goal 
    org.springframework.boot:spring-boot-maven-plugin:1.0.1.RELEASE:repackage 
    failed: 
    Unable to find a single main class from the following candidates

My project has more than one class with a `main` method. How do I tell the Spring Boot Maven plugin which of the classes it should use as the main class?

How do I tell Spring Boot which main class to use for the executable jar?

I have successfully deployed my Maven artifacts (release) into Sonatype&#39;s staging repository with Maven.

Uploading address is https://oss.sonatype.org/service/local/staging/deploy/maven2/

I would like to know how long will it take before I can see them in the central repository?



How long does Sonatype staging take to sync my artifacts with Maven central

Is there any way to input arguments when launching spring-boot application (mvn spring-boot:run) from commandline and then get them in main()?


Get command-line arguments from spring-boot:run

I&#39;m planning to use one of the hadoop file format for my hadoop related project. I **understand** parquet is efficient for column based query and avro for full scan or when we need all the columns data! 

Before I proceed and choose one of the file format, I want to understand what are the disadvantages/drawbacks of one over the other. Can anyone explain it to me in simple terms?

Avro vs. Parquet

Characteristics of Apache Parquet are :

 - Self-describing 
 - Columnar format
 - Language-independent

In comparison to Avro, Sequence Files, RC File etc. I want an overview of the formats. I have already read : [How Impala Works with Hadoop File Formats](https://www.cloudera.com/documentation/enterprise/5-8-x/topics/impala_file_formats.html) , it gives some insights on the formats but I would like to know how the access to data &amp; storage of data is done in each of these formats. How parquet has an advantage over the others?

Content Type	Original Author	Original Content on Stackoverflow
Question	Kesh	View Question on Stackoverflow
Solution 1 - Java	Y.H.	View Answer on Stackoverflow
Solution 2 - Java	Rites	View Answer on Stackoverflow
Solution 3 - Java	blueberry	View Answer on Stackoverflow
Solution 4 - Java	ZhengguanLi	View Answer on Stackoverflow

Avro field default values

Java Problem Overview

Java Solutions

Solution 1 - Java

Solution 2 - Java

Solution 3 - Java

Solution 4 - Java

Importing data into R from google spreadsheet

SQL server stored procedure return a table

Attributions