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In Serialization when inheritance is introduced then on the basis of superclass and subclass certain cases have been defined which make the understanding of Serialization in each case much simpler. The fundamental rules which should be followed are as below.1. When super class is implements Serializable interface and subclass is not.In this case the object of subclass get serialized by default when superclass get serialize, even if subclass doesn't implements Serializable interface.Examplepublic class TestSerialization { public static void main(String[] args) throws IOException, ClassNotFoundException { B obj = new B(); FileOutputStream fos = new ... Read More
A number of functions for hgh level operations on files and directories have been defined in shutil module of Python’s standard library.copy()This function copies a file to a specified file in same or other directory. First parameter to the function is a string representation of existing file. Second argument is either name of resultant file or directory. If it is a directory, the file is coped in it with same name. The metadata of original file is not maintained.>>> import shutil >>> shutil.copy("hello.py", "newdir/") 'newdir/hello.py'copy2()This function is similar to copy() function except for the fact that it retains metadata of ... Read More
The ZIP is one of the most popular file formats used for archiving and compression. It has been in use since the days of MSDOS and PC and has been used by famous PKZIP application.The zipfile module in Python’s standard library provides classes that facilitate the tools for creating, extracting, reading and writing to ZIP archives.ZipFile()This function returns a ZipFile object from a file parameter which can be a string or file object as created by built-in open() function. The function needs a mode parameter whose default value is ‘r’ although it can take ‘w’ or ‘a’ value for opening ... Read More
We can convert any decimal number to its equivalent octal by following program.In this we reserve the reminder we get after divide the given number by 8 as it is the base of Octal and then reverse the order of reminders we have stored by multiplying each reminder by 10.Let understand by following example.Example Live Demopublic class DecimalToOctal { public static void main(String[] args) { int decimal = 84; int octalNumber = 0, i = 1; while (decimal != 0) { octalNumber += (decimal % 8) * i; decimal /= 8; i *= 10; } System.out.println("Octal of given decimal is " + octalNumber); } }OutputOctal of given decimal is 124
In order to find duplicates we can utilize the property of Set in Java that in Java duplicates are not allowed when going to be added in a Set.Add method of set returns true for the adding value which is not added previously to it while it would return false in case the adding value is already present in the Set.For our agenda we would iterate out list or collection of integer and try to add each integer in a set of type integer.Now if integer gets added than this means that it is occurring for first time and not ... Read More
A JavaBean is a specially constructed Java class written in the Java and coded according to the JavaBeans API specifications.Following are the unique characteristics that distinguish a JavaBean from other Java classes −It provides a default, no-argument constructor.It should be serializable and that which can implement the Serializable interface.It may have a number of properties which can be read or written.It may have a number of "getter" and "setter" methods for the properties.JavaBeans PropertiesA JavaBean property is a named attribute that can be accessed by the user of the object. The attribute can be of any Java data type, including ... Read More
The tempfile module in standard library defines functions for creating temporary files and directories. They are created in special temp directories that are defined by operating system file systems. For example, under Windows the temp folder resides in profile/AppData/Local/Temp while in linux the temporary files are held in /tmp directory.Following functions are defined in tempfile moduleTemporaryFile()This function creates a temporary file in the temp directory and returns a file object, similar to built-in open() function. The file is opened in wb+ mode by default, which means it can be simultaneously used to read/write binary data in it. What is important, ... Read More
Lambda expressions are introduced in Java 8 and are touted to be the biggest feature of Java 8. Lambda expression facilitates functional programming, and simplifies the development a lot.SyntaxA lambda expression is characterized by the following syntax.parameter -> expression bodyFollowing are the important characteristics of a lambda expression.Optional type declaration − No need to declare the type of a parameter. The compiler can inference the same from the value of the parameter.Optional parenthesis around parameter − No need to declare a single parameter in parenthesis. For multiple parameters, parentheses are required.Optional curly braces − No need to use curly braces ... Read More
To count occurence of vowels in a string again use Map utility of java as used in calculating occurence of each character in string.Put each vowel as key in Map and put initial value as 1 for each key.Now compare each character with key of map if a character matches with a key then increase its corresponding value by 1.Examplepublic class OccurenceVowel { public static void main(String[] args) { String str = "AEAIOG"; LinkedHashMap hMap = new LinkedHashMap(); hMap.put('A', 0); hMap.put('E', 0); hMap.put('I', 0); hMap.put('O', 0); hMap.put('U', 0); for (int i = 0; i
The order of the words in a string can be reversed and the string displayed with the words in reverse order. An example of this is given as follows.String = I love mangoes Reversed string = mangoes love IA program that demonstrates this is given as follows.Example Live Demoimport java.util.regex.Pattern; public class Example { public static void main(String[] args) { String str = "the sky is blue"; Pattern p = Pattern.compile("\s"); System.out.println("The original string is: " + str); String[] temp = p.split(str); String rev = ... Read More