In case you need to Freeze any particular row anywhere in the sheet you can use (Within `org.apache.poi.ss.usermodel.Sheet`) (Available in POI 3.7 as well)

    Sheet.createFreezePane(int colSplit, int rowSplit, int leftmostColumn, int topRow)

In your case if you want to freeze just your first x rows then the `int leftmostColumn, int topRow` section will get removed and you can use just 

    Sheet.createFreezePane(int colSplit, int rowSplit)

for example 

    sheet1.createFreezePane(0, 5); // this will freeze first five rows

To do this, you can create a freeze pane as follows:

    workbook.getSheetAt(workbook.getActiveSheetIndex()).createFreezePane(0, 1);

This will freeze the first row in place.  There&#39;s another method with more options, so check out the [API][1].

The only thing to note would be if you&#39;re using XSSF workbooks - there is a mention of a bugfix in version 3.8-beta3 that fixed the behavior of freeze panes using XSSF spreadsheets:

&gt; 50884 - XSSF and HSSF freeze panes now behave the same(poi-developers)

I don&#39;t know the details of this, but it would be worth investigating if you&#39;re in that boat.


  [1]: http://poi.apache.org/apidocs/org/apache/poi/ss/usermodel/Sheet.html#createFreezePane%28int,%20int%29

You can not freeze a middle row without getting the rows above it also freezed. 

Say you have 100 rows and your header row is at line 50. You might expect that only row 50 gets locked so that when scrolling from line 1-49, everything is scrolled up and when it reaches line 50, the 50th row scrolls to the top and stays there when lines 51-100 is scrolled. 

But, there is a workaround. What you can do is, group the rows and then freeze them. 

First, group the rows from 1-49 and then freeze panes from 1-50. Now the user can minimize the group and then work with the table with the table header locked and at the top.

    sheet.groupRow(0, 49);
    sheet.createFreezePane(0, 50);

There is a small catch though. MS Excel won&#39;t let you expand/collapse a group if the sheet is protected. For this you need to write a Macro.





    Type t = typeof(int?); //will get this dynamically
    object val = 5; //will get this dynamically
    object nVal = Convert.ChangeType(val, t);//getting exception here


I am getting InvalidCastException in above code. For above I could simply write `int? nVal = val`, but above code is executing dynamically. 

I am getting a value(of non nullable type like int, float, etc) wrapped up in an object (here val), and I have to save it to another object by casting it to another type(which can or cannot be nullable version of it). When 

&gt; Invalid cast from &#39;System.Int32&#39; to &#39;System.Nullable`1[[System.Int32,
&gt; mscorlib, Version=4.0.0.0, Culture=neutral,
&gt; PublicKeyToken=b77a5c561934e089]]&#39;.

An `int`, should be convertible/type-castable to `nullable int`, what is the issue here ?

Invalid cast from &#39;System.Int32&#39; to &#39;System.Nullable`1[[System.Int32, mscorlib]]

I would like to know how to pass a variable to all my templates, without repeating the same code on every method in my views.py file? 

In the example below I would like to make categories (an array of category objects) available to all templates in the web app.

    Eg: I would like to avoid writing &#39;categories&#39;:categories on every method. Is it possible?

**One view method**

    def front_page(request):
        categories = Category.objects.all()
        if is_logged_in(request) is False:
            return render_to_response(&#39;users/signup.html&#39;, {&#39;is_logged_in&#39;: is_logged_in(request), &#39;categories&#39;:categories}, context_instance=RequestContext(request))
        else:
            return render_to_response(&#39;users/front_page.html&#39;, {&#39;is_logged_in&#39;: is_logged_in(request), &#39;categories&#39;:categories},context_instance=RequestContext(request))


**Another view method**

    def another_view_method(request):
        categories = Category.objects.all()
        return render_to_response(&#39;eg/front_page.html&#39;, {&#39;is_logged_in&#39;: is_logged_in(request), &#39;categories&#39;:categories},context_instance=RequestContext(request))

Django - How to make a variable available to all templates?

Is anyone out there familiar with a way to lock a row in a spreadsheet created with Apache POI 3.7? By locking I mean that I want the title row for the columns to remain visible when the user is scrolling through the rows. My created spreadsheet will have 500 rows and it would be beneficial if the column’s names were always visible.

Apache POI Locking Header Rows

<p>Is anyone out there familiar with a way to lock a row in a spreadsheet created with Apache POI 3.7? By locking I mean that I want the title row for the columns to remain visible when the user is scrolling through the rows. My created spreadsheet will have 500 rows and it would be beneficial if the column’s names were always visible.</p>


What&#39;s the difference between the two, cacerts and keystore?

If I use the definition found in these links, [cacerts][1] and [keystore][2], it seems that they&#39;re a collection of certificates, but in context of a (Java) distributed system. Which one is used to authenticate during an SSL connection? Both or just one of them or alternate?

  [1]: http://help.support.gxs.com/help/index.jsp?topic=/security/concepts/what_is_a_cacerts_file.htm
  [2]: http://en.wikipedia.org/wiki/Keystore




What is difference between cacerts and keystore?

I&#39;m very new to design patterns and am having trouble with the difference between [fluent interfaces](http://en.wikipedia.org/wiki/Fluent_interface) and the Builder pattern.

I understand the concept of fluent interfaces. But the builder pattern is a little confusing. I cannot understand the use of a Director in the Builder pattern.  

Can I use the Builder pattern and Fluent Interface together? If so, then how should I do so with a Director and a concrete builder?

My question is **not** about advantages of builder pattern. But the aim of this question is to know the relation between builder pattern and fluent interface.

----------
Edit with UML sequence diagram for Builder from GoF:

![Sequence diagram with director](https://www.plantuml.com/plantuml/svg/TOux3i8m343tdC9ZE_G234YqIAo86mJ7WqMQLeupS7kSqY90iCJsU_4dtpZDNlm8MU-Hx1L6BMDqHfMHPvyK_12PQio0d-B8GgYJL1M-UgQ4GafzuHXe-O5NvunvfPeYTDtU4jZ14sukh2gy6LXhcset5jIcTG6s_cN7sROVcXP-yVuF7oh75p-HNYYNQDCV)

 

What is the difference between a fluent interface and the Builder pattern?

I have two objects of **DateTime**, which need to find the **duration of their difference**, 

I have the following code but not sure how to continue it to get to the expected results as following:

**Example**:

          11/03/14 09:30:58
          11/03/14 09:33:43
          elapsed time is 02 minutes and 45 seconds
          -----------------------------------------------------
          11/03/14 09:30:58 
          11/03/15 09:30:58
          elapsed time is a day
          -----------------------------------------------------
          11/03/14 09:30:58 
          11/03/16 09:30:58
          elapsed time is two days
          -----------------------------------------------------
          11/03/14 09:30:58 
          11/03/16 09:35:58
          elapsed time is two days and 05 minutes
          

**Code**: 

        String dateStart = &quot;11/03/14 09:29:58&quot;;
        String dateStop = &quot;11/03/14 09:33:43&quot;;

        Custom date format
        SimpleDateFormat format = new SimpleDateFormat(&quot;yy/MM/dd HH:mm:ss&quot;);

        Date d1 = null;
        Date d2 = null;
        try {
            d1 = format.parse(dateStart);
            d2 = format.parse(dateStop);
        } catch (ParseException e) {
            e.printStackTrace();
        }

        // Get msec from each, and subtract.
        long diff = d2.getTime() - d1.getTime();
        long diffSeconds = diff / 1000 % 60;
        long diffMinutes = diff / (60 * 1000) % 60;
        long diffHours = diff / (60 * 60 * 1000);
        System.out.println(&quot;Time in seconds: &quot; + diffSeconds + &quot; seconds.&quot;);
        System.out.println(&quot;Time in minutes: &quot; + diffMinutes + &quot; minutes.&quot;);
        System.out.println(&quot;Time in hours: &quot; + diffHours + &quot; hours.&quot;);


How to find the duration of difference between two dates in java?

FIXED: this is a [known bug][1] in maven-compiler-plugin 3.1

I am converting an ant-based build of a 1000+ java-sources project to maven. So far so good, but every time launch `mvn compile` it recompiles everything (instead of reusing old classes)

Using `mvn -X compile` reports that

    [DEBUG] Stale source detected: /project_path/src/main/java/package_path/AFile1.java
    [DEBUG] Stale source detected: /project_path/src/main/java/package_path/AFile2.java
    ...
(**only for files in a certain package**, which is possibly unreferenced from the rest of the code; not my sources, I am just trying to mavenize the build)

Compilation does not fail, and classes with updated timestamps are being generated at

    /project_path/target/classes/package_path/AFile1.class
    /project_path/target/classes/package_path/AFile2.class
    ...

However, when looking at timestamps, the java files have not changed since yesterday, and the class files are current. Why are these sources determined to be stale? How can I debug this issue?.

It is a drag to have to recompile 1k+ files even when no changes have occurred...

----------

Sample output:

    $ mvn clean compile
    [INFO] Scanning for projects...
    [INFO]                                                                         
    [INFO] ------------------------------------------------------------------------
    [INFO] Building MyProject 1.9.0-SNAPSHOT
    [INFO] ------------------------------------------------------------------------
    [WARNING] The POM for net.sourceforge:jffmpeg:jar:1.1.0 is missing, no dependency information available
    [INFO] 
    [INFO] --- maven-clean-plugin:2.4.1:clean (default-clean) @ my-project ---
    [INFO] Deleting /project_path/target
    [INFO] 
    [INFO] --- maven-resources-plugin:2.5:resources (default-resources) @ my-project ---
    [debug] execute contextualize
    [INFO] Using &#39;UTF-8&#39; encoding to copy filtered resources.
    [INFO] skip non existing resourceDirectory /project_path/src/main/resources
    [INFO] 
    [INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ my-project ---
    [INFO] Changes detected - recompiling the module!
    [INFO] Compiling 1162 source files to project_path/target/classes
    ....
    [INFO] ------------------------------------------------------------------------
    [INFO] BUILD SUCCESS
    [INFO] ------------------------------------------------------------------------
    [INFO] Total time: 11.215s
    [INFO] Finished at: Tue Jul 30 12:42:25 CEST 2013
    [INFO] Final Memory: 25M/429M
    [INFO] ------------------------------------------------------------------------
    
    
    
    $ mvn compile
    [INFO] Scanning for projects...
    [INFO]                                                                         
    [INFO] ------------------------------------------------------------------------
    [INFO] Building MyProject 1.9.0-SNAPSHOT
    [INFO] ------------------------------------------------------------------------
    [WARNING] The POM for net.sourceforge:jffmpeg:jar:1.1.0 is missing, no dependency information available
    [INFO] 
    [INFO] --- maven-resources-plugin:2.5:resources (default-resources) @ my-project ---
    [debug] execute contextualize
    [INFO] Using &#39;UTF-8&#39; encoding to copy filtered resources.
    [INFO] skip non existing resourceDirectory /project_path/src/main/resources
    [INFO] 
    [INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ my-project ---
    [INFO] Changes detected - recompiling the module!
    [INFO] Compiling 1162 source files to /project_path/target/classes
    ... 
    [INFO] ------------------------------------------------------------------------
    [INFO] BUILD SUCCESS
    [INFO] ------------------------------------------------------------------------
    [INFO] Total time: 12.140s
    [INFO] Finished at: Tue Jul 30 12:42:44 CEST 2013
    [INFO] Final Memory: 22M/379M
    [INFO] ------------------------------------------------------------------------


  [1]: https://issues.apache.org/jira/browse/MCOMPILER-209

Maven compiler plugin always detecting a set of sources as &quot;stale&quot;

I want to draw circle by canvas. Here is my code:

[MyActivity.java]:

    public class MyActivity extends Activity 
    {
     public void onCreate(Bundle savedInstanceState) 
       {
          ...
          setContentView(new View(this,w,h));
       }
            
    }

[View.java]:

    public class View extends SurfaceView
    {
        public View(Context context, int w, int h)
        {
            super(context);
            Canvas grid = new Canvas(Bitmap.createBitmap(h,w, Bitmap.Config.ARGB_8888));
            grid. drawColor(Color.WHITE);
            Paint paint = new Paint();
            paint.setStyle(Paint.Style.FILL);
            grid.drawCircle(w/2, h/2 , w/2, paint);
        }
    }

So I have just black screen without circle.
Why it does not work? How to fix it?


How to draw circle by canvas in Android?

Is there any other way to merge cells in Excel using Apache POI library?

I was trying using the following, but its not working

    // selecting the region in Worksheet for merging data
    CellRangeAddress region = CellRangeAddress.valueOf(&quot;A&quot; + rowNo + &quot;:D&quot;
				+ rowNo);

    // merging the region
    sheet1.addMergedRegion(region);



Merging cells in Excel using Apache POI

I&#39;m trying to consume data from a spreadsheet in Excel, but always of this error, already tried formatting the worksheet to text and number and still the error persists.

I saw a person using it resolved `cell.setCellType ( Cell.CELL_TYPE_STRING ) ;` but I do not know where I fit this passage in my code.

    WebElement searchbox = driver.findElement(By.name(&quot;j_username&quot;));
    WebElement searchbox2 = driver.findElement(By.name(&quot;j_password&quot;));         

    try {
        FileInputStream file = new FileInputStream(new File(&quot;C:\\paulo.xls&quot;)); 
        HSSFWorkbook workbook = new HSSFWorkbook(file);
        HSSFSheet sheet = workbook.getSheetAt(0);

        for (int i=1; i &lt;= sheet.getLastRowNum(); i++){
            String j_username = sheet.getRow(i).getCell(0).getStringCellValue();
            String j_password = sheet.getRow(i).getCell(0).getStringCellValue();

            searchbox.sendKeys(j_username);
            searchbox2.sendKeys(j_password);
            searchbox.submit();  
     
            driver.manage().timeouts().implicitlyWait(10000, TimeUnit.MILLISECONDS);
        }

        workbook.close();
        file.close();
    } catch (FileNotFoundException fnfe) {
        fnfe.printStackTrace();
    } catch (IOException ioe) {
        ioe.printStackTrace();

Cannot get a text value from a numeric cell “Poi”

I&#39;m trying to write a program that works with Excel docs, but the HSSF format is too small for my requirements. I&#39;m attempting to move to XSSF, but I keep getting errors when trying to use it.

I managed to solve the first two by adding xmlbeans-2.3.0.jar and dom4j-1.6.jar to my program, but now this error is coming up, which doesn&#39;t seem to be resolved by adding the Apache commons jar available on the Apache website.

The error is as follows:

    Exception in thread &quot;main&quot; java.lang.NoClassDefFoundError: org/apache/commons/collections4/ListValuedMap
    	at hot.memes.ExcelCreator.main(ExcelCreator.java:66)
    Caused by: java.lang.ClassNotFoundException: org.apache.commons.collections4.ListValuedMap
    	at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    	at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
    	at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    	... 1 more


Apache POI error loading XSSFWorkbook class

I&#39;m reading an excel-file (file extension xlsx) using org.apache.poi 3.15. 

This is my code:

    try (FileInputStream fileInputStream = new FileInputStream(file); XSSFWorkbook workbook = new XSSFWorkbook(file)) {
        XSSFSheet sheet = workbook.getSheetAt(0);
        Iterator&lt;Row&gt; rowIterator = sheet.iterator();
        while (rowIterator.hasNext()) {
            Row row = rowIterator.next();
    
            Iterator&lt;Cell&gt; cellIterator = row.cellIterator();
            while (cellIterator.hasNext()) {
                Cell cell = cellIterator.next();
                switch (cell.getCellType()) {
                    case Cell.CELL_TYPE_NUMERIC:
                        System.out.print(cell.getNumericCellValue() + &quot;(Integer)\t&quot;);
                        break;
                    case Cell.CELL_TYPE_STRING:
                        System.out.print(cell.getStringCellValue() + &quot;(String)\t&quot;);
                        break;
                }
            }
            System.out.println(&quot;&quot;);
        }
    } catch (Exception e) {
        e.printStackTrace();
    }

I get a warning that `cell.getCellType()` is deprecated. Can anyone tell me the alternative?

Content Type	Original Author	Original Content on Stackoverflow
Question	user1795755	View Question on Stackoverflow
Solution 1 - Java	Sankumarsingh	View Answer on Stackoverflow
Solution 2 - Java	akokskis	View Answer on Stackoverflow
Solution 3 - Java	Mithun P John	View Answer on Stackoverflow

Apache POI Locking Header Rows

Java Problem Overview

Java Solutions

Solution 1 - Java

Solution 2 - Java

Solution 3 - Java

Django - How to make a variable available to all templates?

Invalid cast from 'System.Int32' to 'System.Nullable`1[[System.Int32, mscorlib]]

Attributions