Tutorial by Examples: p

This is a snippet of master report. Two parameters and the connection (for example, jdbc) are passing to the subreport. One value is returned from the subreport back to the master report, this value (variable) can be used in master report <subreport> <reportElement x="0" y=&...

This is a snippet of master report. The datasource is passed to the subreport with help of net.sf.jasperreports.engine.data.JRBeanCollectionDataSource constructor <field name="someFieldWithList" class="java.util.List"/> <!-- ...... --> <subreport> <r...

The JasperReports-plugin by Alex Nederlof is a good alternative of abandoned org.codehaus.mojo:jasperreports-maven-plugin plugin. The adding of plugin is a typical, simple procedure: <build> <plugins> <plugin> <groupId>com.alexnederlof</groupId...

The CLOS MOP provides the hook slot-value-using-class, that is called when a slot is value is accessed, read or modified. Because we only care for modifications in this case we define a method for (setf slot-value-using-class). (defclass document () ((id :reader id :documentation "A hash co...

Classification in Machine Learning is the problem that identifies to which set of categories does a new observation belong. Classification falls under the category of Supervised Machine Learning. Any algorithm that implements classification is known as classifier The classifiers supported in P...

This topic explains the concept of an object reference; it is targeted at people who are new to programming in Java. You should already be familiar with some terms and meanings: class definition, main method, object instance, and the calling of methods "on" an object, and passing parameter...

Every custom loader must directly or indirectly extend the java.lang.ClassLoader class. The main extension points are the following methods: findClass(String) - overload this method if your classloader follows the standard delegation model for class loading. loadClass(String, boolean) - overloa...

The Java language allows you to use new to create instances Integer, Boolean and so on, but it is generally a bad idea. It is better to either use autoboxing (Java 5 and later) or the valueOf method. Integer i1 = new Integer(1); // BAD Integer i2 = 2; // BEST (autoboxing)...

Using new String(String) to duplicate a string is inefficient and almost always unnecessary. String objects are immutable, so there is no need to copy them to protect against changes. In some older versions of Java, String objects can share backing arrays with other String objects. In those ver...

We're all used to the while syntax, that executes its body while the condition is evaluated to true. What if we want to implement an until loop, that executes a loop until the condition is evaluated to true? In Julia, we can do this by creating a @until macro, that stops to execute its body when th...

PHP has built in function pcntl_fork for creating child process. pcntl_fork is same as fork in unix. It does not take in any parameters and returns integer which can be used to differentiate between parent and child process. Consider the following code for explanation <?php // $pid is the P...

Interprocess communication allows programmers to communicate between different processes. For example let us consider we need to write an PHP application that can run bash commands and print the output. We will be using proc_open , which will execute the command and return a resource that we can com...

# This uses the 'sample.xml' given in the XML::Twig example. # Module requirements (1.70 and above for use of load_xml) use XML::LibXML '1.70'; # let's be a good perl dev use strict; use warnings 'all'; # Create the LibXML Document Object my $xml = XML::LibXML->new(); # Where ...

Standalone Common Lisp binaries can be built with buildapp. Before we can use it to generate binaries, we need to install and build it. The easiest way I know how is using quicklisp and a Common Lisp (this example uses [sbcl], but it shouldn't make a difference which one you've got). $ sbcl Thi...

The simplest possible binary you could build Has no dependencies Takes no command line arguments Just writes "Hello world!" to stdout After you've built buildapp, you can just... $ buildapp --eval '(defun main (argv) (declare (ignore argv)) (write-line "Hello, world!"))'...

A more realistic example involves a project you're building with multiple files on disk (rather than an --eval option passed to buildapp), and some dependencies to pull in. Because arbitrary things can happen during the finding and loading of asdf systems (including loading other, potentially unrel...

One example per topic may be pinned by clicking the pin icon in the bottom left corner of the example. So long as a topic is pinned, it will stay at the top of a topic's example collection.

HTML Form Use a file type input and the browser will provide a field that lets the user select a file to upload. Only forms with the post method can send file data. Make sure to set the form's enctype=multipart/form-data attribute. Otherwise the file's name will be sent but not the file's data...

Uploaded files are available in request.files, a MultiDict mapping field names to file objects. Use getlist — instead of [] or get — if multiple files were uploaded with the same field name. request.files['profile'] # single file (even if multiple were sent) request.files.getlist('charts') # li...

WTForms provides a FileField to render a file type input. It doesn't do anything special with the uploaded data. However, since Flask splits the form data (request.form) and the file data (request.files), you need to make sure to pass the correct data when creating the form. You can use a Combine...