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Chained exception helps to relate one exception to other. Often we need to throw a custom exception and want to keep the details of an original exception that in such scenarios we can use the chained exception mechanism. Consider the following example, where we are throwing a custom exception while keeping the message of the original exception.ExampleLive Demopublic class Tester { public static void main(String[] args) { try { test(); }catch(ApplicationException e) { System.out.println(e.getMessage()); } } ... Read More
Byte StreamsJava byte streams are used to perform input and output of 8-bit bytes. Though there are many classes related to byte streams but the most frequently used classes are, FileInputStream and FileOutputStream. Following is an example which makes use of these two classes to copy an input file into an output file −Exampleimport java.io.*; public class CopyFile { public static void main(String args[]) throws IOException { FileInputStream in = null; FileOutputStream out = null; try { in = new ... Read More
The java.io.File class provides useful methods on file. This example shows how to check a file existence by using the file.exists() method of File class.Exampleimport java.io.File; public class Main { public static void main(String[] args) { File file = new File("C:/java.txt"); System.out.println(file.exists()); } }ResultThe above code sample will produce the following result (if the file "java.txt" exists in 'C' drive).trueExampleThe following is another simple example of the file exist or not in java.import java.io.File; import java.io.FileNotFoundException; import java.io.IOException; import java.io.PrintpWriter; import java.nio.file.FileAlreadyExistsException; import java.nio.file.Files; import java.nio.file.Path; import java.nio.file.Paths; public ... Read More
The java.io.File class provides useful methods on file. This example shows how to check a file hidden or not by using the file.isHidden() method of File class.Exampleimport java.io.File; public class Main { public static void main(String[] args) { File file = new File("C:/java.txt"); System.out.println(file.isHidden()); } }ResultThe above code sample will produce the following result (if the file "java.txt" exists and is hidden in 'C' drive).true
Checked exceptionsA checked exception is an exception that occurs at the compile time, these are also called as compile time exceptions. These exceptions cannot simply be ignored at the time of compilation, the programmer should take care of (handle) these exceptions.For example, if you use FileReader class in your program to read data from a file, if the file specified in its constructor doesn't exist, then a FileNotFoundException occurs, and the compiler prompts the programmer to handle the exception.ExampleLive Demoimport java.io.File; import java.io.FileReader; public class FilenotFound_Demo { public static void main(String args[]) { ... Read More
Internet connectivity can be checked using java.net.URL and java.net.URLConnection class. Following are the required steps.Create a URL object and pass it the URL say GoogleCall URL.openConnection() method to get a URLConnection object.Call URLConnection.connect() method to check the internet connectivity. connect() method opens a communications link to the resource referenced by the passed URL if a connection has not already been established.Exampleimport java.io.IOException; import java.net.MalformedURLException; import java.net.URL; import java.net.URLConnection; public class Tester { public static void main(String[] args) { try { URL url = new URL("http://www.google.com"); URLConnection connection ... Read More
The #define creates a macro, which is the association of an identifier or parameterized identifier with a token string. After the macro is defined, the compiler can substitute the token string for each occurrence of the identifier in the source file.#define identifier token-stringThis is how the preprocessor is used. The #define directive causes the compiler to substitute token-string for each occurrence of identifier in the source file. The identifier is replaced only when it forms a token. That is, identifier is not replaced if it appears in a comment, in a string, or as part of a longer identifier.example#include #define ... Read More
Java provides an assignment operator to copy the values but no operator to copy the object. Object class has a clone method which can be used to copy the values of an object without any side-effect. Assignment operator has a side-effect that when a reference is assigned to another reference then a new object is not created and both the reference point to the same object. This means if we change the value in one object then same will reflect in another object as well. clone() method handles this problem. See the below example.ExampleLive Demopublic class Tester { public ... Read More
One of the characteristic features of Python is use of uniform indent to denote a block of statements. A block is initiated by − symbol As soon as − symbol is typed and enter pressed, any Python aware editor will take cursor to next line with increased indent. All lines entered subsequently will follow same level of indent. To signal end of block, indent level must be reduced by pressing backspace.Using above procedure give − after if statement and write statements in true block. Then dedent by backspace and write else − In another block of increased indent enter statements ... Read More
To set a light grey border to an element, use the border border-light class in Bootstrap 4.Adding a light border is easy as shown below − This element has light border You can try to run the following code to implement the border-light-class −ExampleLive Demo Bootstrap Example .demo { width: 150px; height: 220px; margin: 15px; } Demo This element has light border