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Programming Articles
Page 1527 of 2547
Is it possible to use this keyword in static context in java?
A static method or, block belongs to the class and these will be loaded into the memory along with the class. You can invoke static methods without creating an object. (using the class name as reference).Whereas "this" in Java acts as a reference to the current object. But static contexts(methods and blocks) doesn't have any instance they belong to the class.In a simple sense, to use “this” the method should be invoked by an object, which is not always necessary with static methods.Therefore, you cannot use this keyword from a static method.ExampleIn the following Java program, the class ThisExample contains a private ...
Read MoreAdding elements in the middle of an ArrayList in Java
Elements can be added in the middle of an ArrayList by using the java.util.ArrayList.add() method. This method has two parameters i.e. the index at which to insert the element in the ArrayList and the element itself. If there is an element already present at the index specified by ArrayList.add() then that element and all subsequent elements shift to the right by one.A program that demonstrates this is given as follows −Exampleimport java.util.ArrayList; import java.util.List; public class Demo { public static void main(String args[]) throws Exception { List aList = new ArrayList(); ...
Read MoreWhat are defender methods or virtual methods in Java?
The default methods in an interface in Java are also known as defender methods or, virtual methods.The defender/virtual methods are those that will have a default implementation in an interface. You can define defender/virtual methods using the default keyword as −default void display() { System.out.println("This is a default method"); }There is no need to implement these defender/virtual methods in the implementing classes you can call them directly.If you have an interface which is implemented by some classes and if you want to add a new method int it.Then, you need to implement this newly added method in all the ...
Read MoreWhere will be the uploaded files stored in JSP?
A JSP can be used with an HTML form tag to allow users to upload files to the server. An uploaded file can be a text file or a binary or an image file or just any document.Creating a File Upload FormLet us now understand how to create a file upload form. The following HTML code creates an uploader form. Following are the important points to be noted down −The form method attribute should be set to POST method and the GET method cannot be used.The form enctype attribute should be set to multipart/form-data.The form action attribute should be set ...
Read MoreLongStream forEach() method in Java
The forEach() method of the LongStream class in Java performs an action for each element of this stream.The syntax is as followsvoid forEach(LongConsumer action)Here, the parameter action is a non-interfering action to perform on the elements. LongConsumer represents an operation that accepts a single long-valued argument and returns no result.To use the LongStream class in Java, import the following packageimport java.util.stream.LongStream;The following is an example to implement LongStream forEach() method in JavaExampleimport java.util.*; import java.util.stream.LongStream; public class Demo { public static void main(String[] args) { LongStream longStream = LongStream.of(1000L, 12000L, 30000L); ...
Read MoreGet the count of NavigableMap in Java
To get the count of NavigableMap in Java, use the size() method.Let us first create NavigableMap and add elements −NavigableMap n = new TreeMap(); n.put(5, "Tom"); n.put(9, "John"); n.put(14, "Jamie"); n.put(1, "Tim"); n.put(4, "Jackie");Now, get the count −n.size()The following is an example to implement the size() method to get the count of the NavigableMap elements −Exampleimport java.util.*; public class Demo { public static void main(String[] args) { NavigableMap n = new TreeMap(); n.put(5, "Tom"); n.put(9, "John"); ...
Read MoreIntStream min() method in Java
The IntStream min() method in the Java IntStream class is used to get the minimum element from the stream. It returns an OptionalInt describing the minimum element of this stream, or an empty optional if this stream is empty.The syntax is as followsOptionalInt min()Here, OptionalInt is a container object which may or may not contain an int value.Create an IntStream and add some elementsIntStream intStream = IntStream.of(89, 45, 67, 12, 78, 99, 100);Now, get the minimum element of the streamOptionalInt res = intStream.min();The following is an example to implement IntStream min() method in Java. The isPresent() method of the OptionalInt ...
Read MoreCan interfaces have Static methods in Java?
An interface in Java is similar to class but, it contains only abstract methods and fields which are final and static.A static method is declared using the static keyword and it will be loaded into the memory along with the class. You can access static methods using class name without instantiation.Static methods in an interface since java8Since Java8 you can have static methods in an interface (with body). You need to call them using the name of the interface, just like static methods of a class.ExampleIn the following example, we are defining a static method in an interface and accessing ...
Read MoreHow to print date and time in specific format using JSP?
SimpleDateFormat is a concrete class for formatting and parsing dates in a locale-sensitive manner. SimpleDateFormat allows you to start by choosing any user-defined patterns for date-time formatting.Let us modify the above example as follows −Example Display Current Date & Time Display Current Date & Time Compile the above servlet once again and then call this servlet using the URL http://localhost:8080/CurrentDate. You will receive the following result −OutputDisplay Current Date & Time Mon 2010.06.21 at 10:06:44 PM GMT+04:00
Read MoreCreate a directory in Java
A directory can be created with the required abstract path name using the method java.io.File.mkdir(). This method requires no parameters and it returns true on the success of the directory creation or false otherwise.A program that demonstrates this is given as follows −Exampleimport java.io.File; public class Demo { public static void main(String[] args) { try { File file = new File("c:\demo1"); file.createNewFile(); boolean flag = file.mkdir(); System.out.print("Directory created? " + flag); } catch(Exception e) { ...
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