This is recommended to convert to a byte array

    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    ImageIO.write(img, &quot;jpg&quot;, baos);
    byte[] bytes = baos.toByteArray();


Note that calling `close` or `flush` will do nothing, you can see this for yourself by looking at their source/doc:

&gt; Closing a ByteArrayOutputStream has no effect.
&gt;
&gt; The flush method of OutputStream does nothing.

Thus use something like this:

    ByteArrayOutputStream baos = new ByteArrayOutputStream(THINK_ABOUT_SIZE_HINT);
    boolean foundWriter = ImageIO.write(bufferedImage, &quot;jpg&quot;, baos);
    assert foundWriter; // Not sure about this... with jpg it may work but other formats ?
    byte[] bytes = baos.toByteArray();

Here are a few links concerning the size hint:

 - https://stackoverflow.com/questions/7255232/java-memory-efficient-bytearrayoutputstream
 - https://stackoverflow.com/questions/4305101/jpg-bits-per-pixel

Of course always read the source code and docs of the version you are using, do not rely blindly on SO answers.

I am developing a website with Spring, and am trying to serve resources that are not .jsp files (.html for example)

right now i have commented out this part of my servlet configuration

    	&lt;bean id=&quot;viewResolver&quot; class=&quot;org.springframework.web.servlet.view.InternalResourceViewResolver&quot; 
    		p:prefix=&quot;/WEB-INF/jsp/&quot; p:suffix=&quot;.jsp&quot; /&gt;

And tried to return fromthe controller the full path to the resource.

    @Controller
    public class LandingPageController {
	
	protected static Logger logger = Logger.getLogger(LandingPageController.class);
	
	@RequestMapping({&quot;/&quot;,&quot;/home&quot;})
	public String showHomePage(Map&lt;String, Object&gt; model) {
		return &quot;/WEB-INF/jsp/index.html&quot;;	
	   }
    }

the index.html file exists in that folder.

NOTE: when i change the index.html to index.jsp my server now serves the page correctly.

Thank you.

How to serve .html files with Spring

Is there an integer square root somewhere in python, or in standard libraries?  I want it to be exact (i.e. return an integer), and bark if there&#39;s no solution.  

At the moment I rolled my own naive one:

    def isqrt(n):
        i = int(math.sqrt(n) + 0.5)
        if i**2 == n:
            return i
        raise ValueError(&#39;input was not a perfect square&#39;)

But it&#39;s ugly and I don&#39;t really trust it for large integers.  I could iterate through the squares and give up if I&#39;ve exceeded the value, but I assume it would be kinda slow to do something like that.  Also I guess I&#39;d probably be reinventing the wheel, something like this must surely exist in python already...  

Integer square root in python

I see that a number of people have had a similar problem, however I&#39;m yet to try find exactly what I&#39;m looking for. 

So, I have a method which reads an input image and converts it to a byte array:

        File imgPath = new File(ImageName);
 		BufferedImage bufferedImage = ImageIO.read(imgPath);
        WritableRaster raster = bufferedImage .getRaster();
 		DataBufferByte data   = (DataBufferByte) raster.getDataBuffer();

What I now want to do is convert it back into a BufferedImage (I have an application for which I need this functionality). Note that &quot;test&quot; is the byte array. 

        BufferedImage img = ImageIO.read(new ByteArrayInputStream(test));
		File outputfile = new File(&quot;src/image.jpg&quot;);
		ImageIO.write(img,&quot;jpg&quot;,outputfile);

However, this returns the following exception: 

        Exception in thread &quot;main&quot; java.lang.IllegalArgumentException: im == null!

This is because the BufferedImage img is null. I think this has something to do with the fact that in my original conversion from BufferedImage to byte array, information is changed/lost so that the data can no longer be recognised as a jpg. 

Does anyone have any suggestions on how to solve this? Would be greatly appreciated. 

Java: BufferedImage to byte array and back

I see that a number of people have had a similar problem, however I'm yet to try find exactly what I'm looking for.
So, I have a method which reads an input image and converts it to a byte array:
<pre><code class="hljs language-ini"> File imgPath = new File(ImageName);
	BufferedImage bufferedImage = ImageIO.read(imgPath);
 WritableRaster raster = bufferedImage .getRaster();
	DataBufferByte data = (DataBufferByte) raster.getDataBuffer();
</code></pre>
What I now want to do is convert it back into a BufferedImage (I have an application for which I need this functionality). Note that "test" is the byte array.
<pre><code class="hljs language-ini"> BufferedImage img = ImageIO.read(new ByteArrayInputStream(test));
	File outputfile = new File("src/image.jpg");
	ImageIO.write(img,"jpg",outputfile);
</code></pre>
However, this returns the following exception:
<pre><code class="hljs language-php"> Exception in thread "main" java.lang.IllegalArgumentException: im == null!
</code></pre>
This is because the BufferedImage img is null. I think this has something to do with the fact that in my original conversion from BufferedImage to byte array, information is changed/lost so that the data can no longer be recognised as a jpg.
Does anyone have any suggestions on how to solve this? Would be greatly appreciated.

I&#39;m getting a `java.lang.NoSuchFieldException` when trying to run the following method: 

     public void getTimes(String specialty, String day) {
        ArrayList&lt;Tutor&gt; withSpec = new ArrayList&lt;Tutor&gt;();
        for (Tutor t : tutorList){
            try {
                Time startTime = (Time)t.getClass().getField(day + &quot;Start&quot;).get(t);
            } catch (NoSuchFieldException | SecurityException | IllegalAccessException ex) Logger.getLogger(DBHandler.class.getName()).log(Level.SEVERE, null, ex); }

The error is on the line `Time startTime = (Time)t.getClass().getField(day + &quot;Start&quot;).get(t);`

I don&#39;t understand this error, because monStart is a field of the `Tutor` class: 

    Public class Tutor implements Serializable {
    private static final long serialVersionUID = 1L;
    @Id
    @Basic(optional = false)
    @NotNull
    @Column(name = &quot;tutorID&quot;)
    private Integer tutorID;

    .... 

    @Column(name = &quot;monStart&quot;)
    @Temporal(TemporalType.TIME)
     Date monStart;

I&#39;m just learning to use reflection, so I&#39;m sure this is some sort of a syntactical error...

NoSuchFieldException when field exists

I am trying to use Hibernate annotation for writing a model class for my database tables.

I have two tables, each having a primary key User and Question.

    @Entity
    @Table(name=&quot;USER&quot;)
    public class User
    {
        @Id
        @Column(name=&quot;user_id&quot;)
        @GeneratedValue(strategy=GenerationType.AUTO)
        private Long id;

        @Column(name=&quot;username&quot;)
        private String username;

        // Getter and setter
    }

Question Table.

    @Entity
    @Table(name=&quot;QUESTION&quot;)
    public class Questions extends BaseEntity{

        @Id
        @Column(name=&quot;question_id&quot;)
        @GeneratedValue(strategy=GenerationType.AUTO)
        private int id;

        @Column(name=&quot;question_text&quot;)
        private String question_text;

        // Getter and setter
    }

And I have one more table, UserAnswer, which has userId and questionId as foreign keys from the above two tables.

But I am unable to find how I can reference these constraints in the UserAnswer table.

    @Entity
    @Table(name=&quot;UserAnswer &quot;)
    public class UserAnswer
    {
        @Column(name=&quot;user_id&quot;)
        private User user;

        //@ManyToMany
        @Column(name=&quot;question_id&quot;)
        private Questions questions ;

        @Column(name=&quot;response&quot;)
        private String response;

        // Getter and setter
    }

How can I achieve this?


How can I mark a foreign key constraint using Hibernate annotations?

The usual constructor of `ArrayList` is:

    ArrayList&lt;?&gt; list = new ArrayList&lt;&gt;();

But there is also an overloaded constructor with a parameter for its initial capacity:

    ArrayList&lt;?&gt; list = new ArrayList&lt;&gt;(20);

Why is it useful to create an `ArrayList` with an initial capacity when we can append to it as we please?

Why start an ArrayList with an initial capacity?

I&#39;ve got an application that stores some data in DynamoDB using Jackson to marshall my complex object into a JSON. 

For example the object I&#39;m marshalling might look like this:

    private String aString;
    private List&lt;SomeObject&gt; someObjectList;

Where SomeObject might look like this:

    private int anInteger;
    private SomeOtherObject;

and SomeOtherObject might look like this:

    private long aLong;
    private float aFloat; 

This is fine an the object gets marshalled no problem and stored in the DB as a JSON string.

When it comes time to retrieve the data from DynamoDB Jackson automatically retrieves the JSON and converts it back... EXCEPT that &#39;someObjectList&#39; is returned as a `List&lt;LinkedHashMap&gt;` not as a `List&lt;SomeObject&gt;`! This is standard behaviour for Jackson, its not a mistake that this is happening.

So now this leads to a problem. My code base thinks its dealing with a `List&lt;SomeObject&gt;` but the reality is that its handling a `List&lt;LinkedHashMap&gt;`! My question is how do I get my LinkedHashMap back into a &#39;SomeObject&#39;. Obviously this is a manual process but what I mean is I can&#39;t even extract the values.

If I do this:

    for (LinkedHashMap lhm : someObjectList) {
        // Convert the values back
    }

I get a compile error telling me that someObjectList is of type &#39;SomeObject&#39; not LinkedHashMap.

If I do this:

    for (SomeObject lhm : someObjectList) {
        // Convert the values back
    }

I get a runtime error telling me that LinkedHashMap cannot be cast to &#39;SomeObject&#39;.


Casting LinkedHashMap to Complex Object

If I synchronized two methods on the same class, can they run simultaneously **on the same object**? For example:

    class A {
    	public synchronized void methodA() {
    		//method A
    	}
    
    	public synchronized void methodB() {
    		// method B
    	}
    }

I know that I can&#39;t run `methodA()` twice on same object in two different threads. same thing in `methodB()`.

But can I run `methodB()` on different thread while `methodA()` is still running? (same object)

If I synchronized two methods on the same class, can they run simultaneously?

I have an ActiveRecord result of a find operation:

    tasks_records = TaskStoreStatus.find(
      :all,
      :select =&gt; &quot;task_id, store_name, store_region&quot;,
      :conditions =&gt; [&quot;task_status = ? and store_id = ?&quot;, &quot;f&quot;, store_id]
    )

Now I want to convert this results into an array of hashes like this:

    [0] -&gt;  { :task_d =&gt; 10, :store_name=&gt; &quot;Koramanagala&quot;, :store_region=&gt; &quot;India&quot; }
    
    [1] -&gt; { :task_d =&gt; 10, :store_name=&gt; &quot;Koramanagala&quot;, :store_region=&gt; &quot;India&quot; }
    
    [2] -&gt;  { :task_d =&gt; 10, :store_name=&gt; &quot;Koramanagala&quot;, :store_region=&gt; &quot;India&quot; }

so that I will be able to iterate through the array and to add more elements to hashes and later to convert the result into `JSON` for my API response. How can I do this?

How to convert ActiveRecord results into an array of hashes

As described [here](https://stackoverflow.com/a/1374131/460138), a quick way to append array b to array a in javascript is `a.push.apply(a, b)`.

You&#39;ll note that the object a is used twice.  Really we just want the `push` function, and `b.push.apply(a, b)` accomplishes exactly the same thing -- the first argument of apply supplies the `this` for the applied function.

I thought it might make more sense to directly use the methods of the Array object: `Array.push.apply(a, b)`.  But this doesn&#39;t work!  

I&#39;m curious why not, and if there&#39;s a better way to accomplish my goal.  (Applying the `push` function without needing to invoke a specific array twice.)

Why doesn&#39;t Array.push.apply work?

I am looking to sort the following array based on the values of [][0]

    double[][] myArr = new double[mySize][2];

so for example, myArr contents is:
    
    1      5
    13     1.55
    12     100.6
    12.1   .85


I want it to get to:

    1      5
    12     100.6
    12.1   .85
    13     1.55


I am looking to do this without having to implement my own sort.

java Arrays.sort 2d array

I already know that `apply` and `call` are similar functions which set `this` (context of a function).

The difference is with the way we send the arguments (manual vs array)

**Question:**

But when should I use the  `bind()` method ?

    var obj = {
      x: 81,
      getX: function() {
        return this.x;
      }
    };
    
    alert(obj.getX.bind(obj)());
    alert(obj.getX.call(obj));
    alert(obj.getX.apply(obj));


 

     
[jsbin][1]


  [1]: http://jsbin.com/awewof/1/edit

Javascript call() &amp; apply() vs bind()?

I&#39;ve a following associative array named `$data`

    Array
    (
        [0] =&gt; Array
            (
                [transaction_user_id] =&gt; 359691e27b23f8ef3f8e1c50315cd506
                [transaction_no] =&gt; 19500912050218
                [transaction_total_amount] =&gt; 589.00
                [transaction_date] =&gt; 1335932419
                [transaction_status] =&gt; cancelled
            )
    
        [1] =&gt; Array
            (
                [transaction_user_id] =&gt; 9def02e6337b888d6dbe5617a172c18d
                [transaction_no] =&gt; 36010512050819
                [transaction_total_amount] =&gt; 79.00
                [transaction_date] =&gt; 1336476696
                [transaction_status] =&gt; cancelled
            )
    
        [2] =&gt; Array
            (
                [transaction_user_id] =&gt; 9def02e6337b888d6dbe5617a172c18d
                [transaction_no] =&gt; 19020512050820
                [transaction_total_amount] =&gt; 299.00
                [transaction_date] =&gt; 1336476739
                [transaction_status] =&gt; cancelled
            )
    
        [3] =&gt; Array
            (
                [transaction_user_id] =&gt; 9def02e6337b888d6dbe5617a172c18d
                [transaction_no] =&gt; 27050512050821
                [transaction_total_amount] =&gt; 79.00
                [transaction_date] =&gt; 1336476927
                [transaction_status] =&gt; cancelled
            )
    
        [4] =&gt; Array
            (
                [transaction_user_id] =&gt; 8e9050a3646c98342b9ba079fba80982
                [transaction_no] =&gt; 12070512050822
                [transaction_total_amount] =&gt; 129.00
                [transaction_date] =&gt; 1336477032
                [transaction_status] =&gt; cancelled
            )
    
    )

and I want to convert the value of key `[transaction_date]` into user readable format (i.e. mm/dd/yyyy). For that I written the following code in a function which returns the whole array:

   

     foreach($data as $value)
     {
       	$value[transaction_date]=date(&#39;d/m/Y&#39;,$value[transaction_date]);
     }
        
     return $data;

My problem is I&#39;m getting the same array without changing the value of `[transaction_date]` for all the array elements. Actually array with updated values for `[transaction_date]` is expected to be returned. 
Can anyone help me out to resolve this issue? Thanks in advance.

How to update specific key&#39;s value in an associative array in PHP?

I got [this code](https://stackoverflow.com/questions/5501427/php-filesize-mb-kb-conversion) to covert size in bytes via PHP.

Now I want to convert those sizes to _human readable_ sizes using JavaScript. I tried to convert this code to JavaScript, which looks like this:

    function formatSizeUnits(bytes){
      if      (bytes &gt;= 1073741824) { bytes = (bytes / 1073741824).toFixed(2) + &quot; GB&quot;; }
      else if (bytes &gt;= 1048576)    { bytes = (bytes / 1048576).toFixed(2) + &quot; MB&quot;; }
      else if (bytes &gt;= 1024)       { bytes = (bytes / 1024).toFixed(2) + &quot; KB&quot;; }
      else if (bytes &gt; 1)           { bytes = bytes + &quot; bytes&quot;; }
      else if (bytes == 1)          { bytes = bytes + &quot; byte&quot;; }
      else                          { bytes = &quot;0 bytes&quot;; }
      return bytes;
    }

Is this the correct way of doing this? Is there an easier way?

Correct way to convert size in bytes to KB, MB, GB in JavaScript

I&#39;m converting something from VB into C#. Having a problem with the syntax of this statement:

    if ((searchResult.Properties[&quot;user&quot;].Count &gt; 0))
    {
        profile.User = System.Text.Encoding.UTF8.GetString(searchResult.Properties[&quot;user&quot;][0]);
    }
I then see the following errors:

&gt; Argument 1: cannot convert from &#39;object&#39; to &#39;byte[]&#39;
&gt; 
&gt; The best overloaded method match for
&gt; &#39;System.Text.Encoding.GetString(byte[])&#39; has some invalid arguments

I tried to fix the code based on [this][1] post, but still no success

    string User = Encoding.UTF8.GetString(&quot;user&quot;, 0);

Any suggestions?


  [1]: https://stackoverflow.com/questions/10180864/converting-byte-array-to-string-not-working-in-c-sharp

Converting string to byte array in C#

I have an instance of a struct that I defined and I would like to convert it to an array of bytes. I tried []byte(my_struct), but that did not work. Also, I was pointed to the &lt;a href=&quot;http://golang.org/pkg/encoding/binary/&quot;&gt;binary package&lt;/a&gt;, but I am not sure which function I should use and how I should use it. An example would be greatly appreciated.

In Go, how can I convert a struct to a byte array?

I&#39;m trying to develop a tool that read a binary file, makes some changes and save it. What I&#39;m trying to do is make a list of each line in the file, work with several lines and then join the list again.

This is what I tried:

    file = open(&#39;myFile.exe&#39;, &#39;r+b&#39;)

    aList = []
    for line in f:
        aList.append(line)

    #Here im going to mutate some lines.

    new_file = &#39;&#39;.join(aList)

and give me this error:

    TypeError: sequence item 0: expected str instance, bytes found

which makes sense because I&#39;m working with bytes.



Is there a way I can use join function o something similar to join bytes?
Thank you.


 

Joining byte list with python

I&#39;m trying to load image from string like as PHP function `imagecreatefromstring`

How can I do that?

I have MySQL blob field image. I&#39;m using **MySQLdb** and don&#39;t want create temporary file for working with images in PyOpenCV.

NOTE: need cv (not cv2) wrapper function

Python OpenCV load image from byte string

I have 10,000 photos that need to be resized so I have a Java program to do that. Unfortunately, the quality of the image is poorly lost and I don&#39;t have access to the uncompressed images.


    import java.awt.Graphics;
    import java.awt.AlphaComposite;
    import java.awt.Graphics2D;
    import java.awt.Image;
    import java.awt.RenderingHints;
    import java.awt.image.BufferedImage;
    import java.io.File;
    import java.io.IOException;
     
    
    import javax.imageio.ImageIO;
    /**
     * This class will resize all the images in a given folder
     * @author 
     *
     */
    public class JavaImageResizer {
     
        public static void main(String[] args) throws IOException {
     
            File folder = new File(&quot;/Users/me/Desktop/images/&quot;);
            File[] listOfFiles = folder.listFiles();
            System.out.println(&quot;Total No of Files:&quot;+listOfFiles.length);
            BufferedImage img = null;
            BufferedImage tempPNG = null;
            BufferedImage tempJPG = null;
            File newFilePNG = null;
            File newFileJPG = null;
            for (int i = 0; i &lt; listOfFiles.length; i++) {
                  if (listOfFiles[i].isFile()) {
                    System.out.println(&quot;File &quot; + listOfFiles[i].getName());
                    img = ImageIO.read(new File(&quot;/Users/me/Desktop/images/&quot;+listOfFiles[i].getName()));
                    tempJPG = resizeImage(img, img.getWidth(), img.getHeight());
                    newFileJPG = new File(&quot;/Users/me/Desktop/images/&quot;+listOfFiles[i].getName()+&quot;_New&quot;);
                    ImageIO.write(tempJPG, &quot;jpg&quot;, newFileJPG);
                  }
            }
            System.out.println(&quot;DONE&quot;);
        }
     
        /**
         * This function resize the image file and returns the BufferedImage object that can be saved to file system.
         */
            public static BufferedImage resizeImage(final Image image, int width, int height) {
    	int targetw = 0;
    	int targeth = 75;
    	
    	if (width &gt; height)targetw = 112;
    	else targetw = 50;
    	
    	do {
    		if (width &gt; targetw) {
    			width /= 2;
    			if (width &lt; targetw) width = targetw;
    		}
    		
    		if (height &gt; targeth) {
    			height /= 2;
    			if (height &lt; targeth) height = targeth;
    		}
    	} while (width != targetw || height != targeth);
    	
        final BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        final Graphics2D graphics2D = bufferedImage.createGraphics();
        graphics2D.setComposite(AlphaComposite.Src);
        graphics2D.setRenderingHint(RenderingHints.KEY_INTERPOLATION,RenderingHints.VALUE_INTERPOLATION_BILINEAR);
        graphics2D.setRenderingHint(RenderingHints.KEY_RENDERING,RenderingHints.VALUE_RENDER_QUALITY);
        graphics2D.setRenderingHint(RenderingHints.KEY_ANTIALIASING,RenderingHints.VALUE_ANTIALIAS_ON);
        graphics2D.drawImage(image, 0, 0, width, height, null);
        graphics2D.dispose();
    	
        return bufferedImage;
    }

An image I am working with is this:
![Firwork - original - large][1]

This is the manual resizing I&#39;ve done in Microsoft Paint:

![resize - using Paint - small][2]

and this is the output from my program [bilinear]:

![resize - using java program - small][3]

**UPDATE:** No significant difference using `BICUBIC`

and this is the output from my program [bicubic]:

![enter image description here][4]


is there anyway to increase the quality of the program output so I don&#39;t have to manually resize all photos?

Thank you in advance!


  [1]: http://i.stack.imgur.com/X0aPT.jpg
  [2]: http://i.stack.imgur.com/bbPis.jpg
  [3]: http://i.stack.imgur.com/Z7tD3.jpg
  [4]: http://i.stack.imgur.com/oMU52.jpg

Content Type	Original Author	Original Content on Stackoverflow
Question	user1875290	View Question on Stackoverflow
Solution 1 - Java	Nikolay Kuznetsov	View Answer on Stackoverflow
Solution 2 - Java	Christophe Roussy	View Answer on Stackoverflow

Java: BufferedImage to byte array and back

Java Problem Overview

Java Solutions

Solution 1 - Java

Solution 2 - Java

Integer square root in python

How to serve .html files with Spring

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