You don&#39;t have to close `ByteArrayInputStream`, the moment it is not referenced by any variable, garbage collector will release the stream and `somebytes` (of course assuming they aren&#39;t referenced somewhere else).

**However** it is always a good practice to close every stream, in fact, maybe the implementation creating the stream will change in the future and instead of raw bytes you&#39;ll be reading file? Also static code analyzing tools like PMD or &lt;strike&gt;FindBugs&lt;/strike&gt; (see comments) will most likely complain.

If you are bored with closing the stream and being forced to handle impossible `IOException`, you might use [IOUtils](http://commons.apache.org/io/api-1.4/org/apache/commons/io/IOUtils.html#closeQuietly(java.io.InputStream)):

    IOUtils.closeQuietly(stream);

It is always good practice to close your readers.  However not closing a ByteArrayInputStream does not have as heavy of a potential negative effect because you are not accessing a file, just a byte array in memory.

As @TomaszNurkiewicz mentioned it&#39;s always good to close the opened stream. Another good way to let it do the try block itself. Use try with resource  like.......                                                                                     
 

    try ( InputStream inputStream = new ByteArrayInputStream(bytes); Workbook workBook = new XSSFWorkbook(inputStream)) { 

     

here Workbook and InputStream both implements Closeable Interface so once try block completes ( normally or abruptly), stream will be closed for sure.

Resources need to be closed in a `finally` (or equivalent). But where you just have some bytes, no it doesn&#39;t matter. Although when writing, be careful to `flush` in the happy case.

I need to scroll a JScrollPane to the bottom. The JScrollPane contains a JPanel, which contains a number of JLabel&#39;s.

To scroll to the top, I just do:

    scrollPane.getViewport().setViewPosition(new Point(0,0));

but how do I scroll exactly to the very bottom? (Too far and it jitters)

Scroll JScrollPane to bottom

I am querying a data source for dates. Depending on the item I am searching for, it may have more than date associated with it.

    get-date ($Output | Select-Object -ExpandProperty &quot;Date&quot;)

An example of the output looks like:

    Monday, April 08, 2013 12:00:00 AM
    Friday, April 08, 2011 12:00:00 AM

I would like to compare these dates and return which one is set further out into the future.


PowerShell: Comparing dates

Short question,

I saw in some old code where a `ByteArrayInputStream` was created like:

    new BufferedReader(new InputStreamReader(new ByteArrayInputStream(somebytes)));

And then the `BufferedReader` is used to read out `somebytes` line by line.  
All working fine, but I noticed that the `BufferedReader` is never closed.  
This is all working in a long running websphere application, the `somebytes` are not terrible big (200k most), it is only invoked a few times a week and we&#39;re not experiencing any apparent memory leaks. So I expect that all the objects are successfully garbage collected.

I always (once) learned that input/output streams need to be closed, in a `finally` statement. Are `ByteStreams` the exception to this rule?

kind regards
Jeroen.

Do I need to close a ByteArrayInputStream?

Short question,
I saw in some old code where a <code>ByteArrayInputStream</code> was created like:
<pre><code class="hljs language-arduino">new BufferedReader(new InputStreamReader(new ByteArrayInputStream(somebytes)));
</code></pre>
And then the <code>BufferedReader</code> is used to read out <code>somebytes</code> line by line. 
All working fine, but I noticed that the <code>BufferedReader</code> is never closed. 
This is all working in a long running websphere application, the <code>somebytes</code> are not terrible big (200k most), it is only invoked a few times a week and we're not experiencing any apparent memory leaks. So I expect that all the objects are successfully garbage collected.
I always (once) learned that input/output streams need to be closed, in a <code>finally</code> statement. Are <code>ByteStreams</code> the exception to this rule?
kind regards
Jeroen.

I have a `log4j` properties something like below. Everything that is logged in `TextProcessor.log` is something above WARN level. I don&#39;t understand the threshold that is set here to debug. Can someone explain what the threshold does?

    log4j.logger.TextProcessor=warn,TextProcessor 
    
    log4j.appender.TextProcessor=org.apache.log4j.RollingFileAppender
    log4j.appender.TextProcessor.File=C:/project/logs/TextProcessor.log
    log4j.appender.TextProcessor.MaxFileSize=10MB
    log4j.appender.TextProcessor.MaxBackupIndex=10
    log4j.appender.TextProcessor.Threshold=debug
    log4j.appender.TextProcessor.layout=org.apache.log4j.PatternLayout
    log4j.appender.TextProcessor.layout.ConversionPattern=[%d] [%5p] (%F:%L) - %m%n

What does threshold mean in Log4J?

I know of date formats such as &lt;br/&gt;
`&quot;yyyy-mm-dd&quot;` -which displays date in format `2011-02-26`&lt;br/&gt;
`&quot;yyyy-MMM-dd&quot;`-which displays date in format `2011-FEB-26`

to be used in eg:

    SimpleDateFormat formatter = new SimpleDateFormat(
    				&quot;yyyy/MMM/dd &quot;);

I want a format which would help me display the day of the week like `2011-02-MON` or anything.  I just want the day of the week to be displayed in characters with the month and the year.  Can you tell me of a format like this?

Is there a date format to display the day of the week in java?

How can I create and fetch associative arrays in Java like I can in PHP?

For example:

    $arr[0][&#39;name&#39;] = &#39;demo&#39;;
    $arr[0][&#39;fname&#39;] = &#39;fdemo&#39;;
    $arr[1][&#39;name&#39;] = &#39;test&#39;;
    $arr[1][&#39;fname&#39;] = &#39;fname&#39;;

Java associative-array

I already know the definition of immutable classes but I need a few examples. 



Examples of immutable classes

I&#39;m developing a game for Android. It uses a surface view and uses the sort of standard 2D drawing APIs provided. When I first released the game, I was doing all sorts of daft things like re-drawing 9-patches on each frame and likewise with text. I have since optimised much of this by drawing to Bitmap objects and drawing them each frame, only re-drawing onto the Bitmap objects when required. 

I&#39;ve received complaints about battery drain before, and following my modifications I&#39;d like to know (scientifically) if I&#39;ve made any improvements. Unfortunately, I don&#39;t have any prior data to go by, so it would be most useful to compare the performance to some other game.

I&#39;ve been running Traceview, and using the results of it mostly for the purposes of identifying CPU-time-consuming methods. 

So -- **what&#39;s the best way of determining my app&#39;s battery performance, and what&#39;s a good benchmark?**

I know I can look at the %s of different apps through the settings, but this is again unscientific, as the figure I get from this also depends on what&#39;s happening in all of the other apps. I&#39;ve looked through (most of) Google&#39;s documentation, and although the message is clear that you *should* be saving battery (and it gives the occasional tip as to how), there is little indication of how I can measure how well my app is performing. The last thing I want are more complaints of battery drain in the Android Market!

Thanks in advance.

***

EDIT
----

Thanks for all your helpful advice/suggestions. What I really want to know is **how I can use the data coming from Traceview (ie: CPU time in ms spent on each frame of the game) to determine battery usage** (if this is at all possible). Reading back on my original question, I can see I was a bit vague. Thanks again.


Is my Android App Draining Battery?

I need to read a large text file of around 5-6 GB line by line using Java.

How can I do this quickly?


How can I read a large text file line by line using Java?

I have a high performance application that is handling a very large amount of data.  It is receiving, analysing and discarding enormous amounts of information over very short periods of time.  This causes a fair amount of object churn that I am currently trying to optimize, but it also causes a secondary problem.  When Garbage Collection kicks in it can cause some long delays as it cleans things up (by long I mean 10s to 100s of milliseconds).  99% of the time this is acceptable, but for brief windows of time about 1-2 minutes long I need to be absolutely sure that Garbage Collection does not cause a delay.  I know when these periods of time will occur beforehand and I just need a way to make sure that Garbage collection doesn&#39;t happen during this period.  The application is written in C# using .NET 4.0 Framework and uses both managed and unmanaged code if that matters.

My questions are;

 1. Is it possible to briefly pause Garbage Collection for the entire program?
 2. Is it possible to use System.GC.Collect() to force garbage collection before the window I need free of Garbage Collection and if I do how long will I be Garbage Collection free?
 3. What advice do people have on minimizing the need for Garbage Collection overall? 

Note -  this system is fairly complex with lots of different components.  I am hoping to avoid going to a approach where I have to implement a custom IDisposable interface on every class of the program. 

Prevent .NET Garbage collection for short period of time

What is the difference between `System.gc()` and `Runtime.gc()`?


Difference between system.gc() and runtime.gc()

I have a C# Windows Service that I recently moved from .NET 3.5 to .NET 4.0. No other code changes were made.

When running on 3.5, memory utilzation for a given work load was roughly 1.5 GB of memory and throughput was 20 X per second. (The X doesn&#39;t matter in the context of this question.)

The exact same service running on 4.0 uses between 3GB and 5GB+ of memory, and gets less than 4 X per second. In fact, the service will typically end up stalling out as memory usage continue to climb until my system is siting at 99% utilization and page file swapping goes nuts.

I&#39;m not sure if this has to do with garbage collection, or what, but I&#39;m having trouble figuring it out. My window service uses the &quot;Server&quot; GC via the config file switch seen below:

      &lt;runtime&gt;
        &lt;gcServer enabled=&quot;true&quot;/&gt;
      &lt;/runtime&gt;

Changing this option to false didn&#39;t seem to make a difference. Futhermore, from the reading I&#39;ve done on the new GC in 4.0, the big changes only effect the workstation GC mode, not server GC mode. So perhaps GC has nothing to do with the issue.

Ideas?

Very High Memory Usage in .NET 4.0

I need to check the time amount to run GetTypes() after loading the dll.
The code is as follows.

    Assembly assem = Assembly.LoadFrom(file);
    sw = Stopwatch.StartNew();
    var types1 = assem.GetTypes();
    sw.Stop();
    double time1 = sw.Elapsed.TotalMilliseconds;

I&#39;d like to unload and reload the dll to check the time to spend in running GetTypes() again.

 * How can I unload it? `assem = null` is good enough? 
 * Is there an explicit way to call garbage collector to reclaim the resource allocated to assem?

Unloading the Assembly loaded with Assembly.LoadFrom()

I&#39;m trying to read a text file line by line using InputStream from the assets directory in Android.

I want to convert the InputStream to a BufferedReader to be able to use the readLine().

I have the following code:

    InputStream is;
    is = myContext.getAssets().open (&quot;file.txt&quot;);
    BufferedReader br = new BufferedReader (is);

The third line drops the following error:

&lt;pre&gt;Multiple markers at this line
The constructor BufferedReader (InputStream) is undefinded.&lt;/pre&gt;

What I&#39;m trying to do in C++ would be something like:

    StreamReader file;
    file = File.OpenText (&quot;file.txt&quot;);
        
    line = file.ReadLine();
    line = file.ReadLine();
    ...

What am I doing wrong or how should I do that? Thanks!

Convert InputStream to BufferedReader

I have a handy function that I&#39;ve used in Java for converting an InputStream to a String.  Here is a direct translation to Scala:

      def inputStreamToString(is: InputStream) = {
        val rd: BufferedReader = new BufferedReader(new InputStreamReader(is, &quot;UTF-8&quot;)) 
        val builder = new StringBuilder()    
        try {
          var line = rd.readLine 
          while (line != null) { 
            builder.append(line + &quot;\n&quot;)
            line = rd.readLine
          }
        } finally {
          rd.close
        }
        builder.toString
      }

Is there an idiomatic way to do this in scala?

Idiomatic way to convert an InputStream to a String in Scala

I am trying to send a post request to a url using HttpURLConnection (for using cUrl in java). 
The content of the request is xml and at the end point, the application processes the xml and stores a record to the database and then sends back a response in form of xml string. The app is hosted on apache-tomcat locally. 

When I execute this code from the terminal, a row gets added to the db as expected. But an exception is thrown as follows while getting the InputStream from the connection

    java.io.FileNotFoundException: http://localhost:8080/myapp/service/generate
    	at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1401)
    	at org.kodeplay.helloworld.HttpCurl.main(HttpCurl.java:30)

Here is the code

    public class HttpCurl {
        public static void main(String [] args) {
    		
    		HttpURLConnection con;
    		
    		try {
    			con = (HttpURLConnection) new URL(&quot;http://localhost:8080/myapp/service/generate&quot;).openConnection();
    			con.setRequestMethod(&quot;POST&quot;);
    			con.setDoOutput(true);
    			con.setDoInput(true);
    				
    			File xmlFile = new File(&quot;test.xml&quot;);
    			
    			String xml = ReadWriteTextFile.getContents(xmlFile);				
    			
    			con.getOutputStream().write(xml.getBytes(&quot;UTF-8&quot;));
    			InputStream response = con.getInputStream();
    			
    			BufferedReader reader = new BufferedReader(new InputStreamReader(response));
    			for (String line ; (line = reader.readLine()) != null;) {
    			    System.out.println(line);
    			}
    			reader.close();
    			
    		} catch (FileNotFoundException e) {
    			e.printStackTrace();
    		} catch (MalformedURLException e) {
    			e.printStackTrace();
    		} catch (IOException e) {
    			e.printStackTrace();
    		}
    	}
      }

Its confusing because the exception is traced to the line `InputStream response = con.getInputStream();` and there doesn&#39;t seem to be any file involved for a FileNotFoundException. 

When I try to open a connection to an xml file directly, it doesn&#39;t throw this exception.

The service app uses spring framework and Jaxb2Marshaller to create the response xml.

The class ReadWriteTextFile is taken from [here][1]


Thanks.

**Edit:**
Well it saves the data in the DB and sends back a 404 response status code at the same time.

I also tried doing a curl using php and print out the `CURLINFO_HTTP_CODE` which turns out to be 200. 

Any ideas on how do I go about debugging this ? Both service and client are on the local server. 

**Resolved:**
I could solve the problem after referring to an [answer][2] on SO itself. 

It seems HttpURLConnection always returns 404 response when connecting to a url with a non standard port. 

Adding these lines solved it

    con.setRequestProperty(&quot;User-Agent&quot;,&quot;Mozilla/5.0 ( compatible ) &quot;);
    con.setRequestProperty(&quot;Accept&quot;,&quot;*/*&quot;);


  [1]: http://www.javapractices.com/topic/TopicAction.do?Id=42
  [2]: https://stackoverflow.com/questions/941628/urlconnection-filenotfoundexception-for-non-standard-http-port-sources/2274535#2274535

FileNotFoundException while getting the InputStream object from HttpURLConnection

I am on the stage of development, where I have two modules and from one I got output as a `OutputStream` and second one, which accepts only `InputStream`. Do you know how to convert `OutputStream` to `InputStream` (not vice versa, I mean really this way) that I will be able to connect these two parts?

Thanks

How to convert OutputStream to InputStream?

I have a InputStream that I pass to a method to do some processing. I will use the same InputStream in other method, but after the first processing, the InputStream appears be closed inside the method.

How I can clone the InputStream to send to the method that closes him? There is another solution?

EDIT: the methods that closes the InputStream is an external method from a lib. I dont have control about closing or not.

    private String getContent(HttpURLConnection con) {
        InputStream content = null;
        String charset = &quot;&quot;;
        try {
            content = con.getInputStream();
            CloseShieldInputStream csContent = new CloseShieldInputStream(content);
            charset = getCharset(csContent);            
            return  IOUtils.toString(content,charset);
        } catch (Exception e) {
            System.out.println(&quot;Error downloading page: &quot; + e);
            return null;
        }
    }

    private String getCharset(InputStream content) {
        try {
            Source parser = new Source(content);
            return parser.getEncoding();
        } catch (Exception e) {
            System.out.println(&quot;Error determining charset: &quot; + e);
            return &quot;UTF-8&quot;;
        }
    }


Content Type	Original Author	Original Content on Stackoverflow
Question	dr jerry	View Question on Stackoverflow
Solution 1 - Java	Tomasz Nurkiewicz	View Answer on Stackoverflow
Solution 2 - Java	jzd	View Answer on Stackoverflow
Solution 3 - Java	KulDeep	View Answer on Stackoverflow
Solution 4 - Java	Tom Hawtin - tackline	View Answer on Stackoverflow

Do I need to close a ByteArrayInputStream?

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PowerShell: Comparing dates

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