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Class variables are variables that are declared outside the__init__method. These are static elements, meaning, they belong to the class rather than to the class instances. These class variables are shared by all instances of that class. Example code for class variables Exampleclass MyClass: __item1 = 123 __item2 = "abc" def __init__(self): #pass or something elseYou'll understand more clearly with more code −class MyClass: stat_elem = 456 def __init__(self): self.object_elem = 789 c1 = MyClass() c2 = MyClass() # Initial values of both elements >>> print c1.stat_elem, c1.object_elem 456 ... Read More
Attributes of a classEverything, almost everything in Python is an object. Every object has attributes and methods. Thus attributes are very fundamental in Python. A class is a construct which is a collection of similar objects. A class also has attributes. There will be a difference between the class attributes and instance attributes. The class attributes are shared by the instances of the class but it not true vice versa.ExampleWe can get a list of the attributes of an object using the built-in “dir” function. For example −>>> s = 'abc' >>> len(dir(s)) 71 >>> dir(s)[:5] ['__add__', '__class__', '__contains__', '__delattr__', ... Read More
Cast operator in java is used to convert one data type to other.Examplepublic class Sample { public static void main(String args[]) { double d = 20.3; int i = (int)d; System.out.println(i); } }Output20
The instanceof operator is used only for object reference variables. The operator checks whether the object is of a particular type (class type or interface type).Examplepublic class Test { public static void main(String args[]) { String name = "James"; boolean result = name instanceof String; System.out.println(result); } }Outputtrue
The conditional operator is also known as the ternary operator. This operator consists of three operands and is used to evaluate Boolean expressions. The goal of the operator is to decide; which value should be assigned to the variable. The operator is written as:variable x = (expression)? value if true: value if falseExamplepublic class Test { public static void main(String args[]) { int a, b; a = 10; b = (a == 1) ? 20: 30; System.out.println("Value of b is: " + b); b = (a == 10) ? 20: 30; System.out.println(“Value of b is: " + b); } }OutputValue of b is: 30 Value of b is: 20
The isAlive() method of the Thread class returns true if the thread is alive, which is anytime after the thread has been started but before it runs to completion.Exampleclass first implements Runnable { public void run() { try { for(int i=0; i
The flush() method of the FileWriter class flushes the contents of the file. You can use this method to truncate a file.Exampleimport java.io.File; import java.io.FileWriter; public class FileTruncate { public static void main(String args[]) throws Exception { File file = new File("myData"); FileWriter fw = new FileWriter(file, false); fw.flush(); System.out.println("File truncated"); } }OutputFile truncated
You can access a plain text using the File class.ExampleLive Demoimport java.io.File; public class ReadFile { public static void main(String[] args) { File f = null; String str = "data.txt"; try { f = new File(str); boolean bool = f.canExecute(); String a = f.getAbsolutePath(); System.out.print(a); System.out.println(" is executable: "+ bool); } catch (Exception e) { e.printStackTrace(); } } }Output C:\Users\data is executable: true
You can sort an array using sort() method of the Arrays class.ExampleLive Demoimport java.util.Arrays; public class MainClass { public static void main(String args[]) throws Exception { int array[] = { 2, 5, -2, 6, -3, 8, 0, -7, -9, 4 }; Arrays.sort(array); printArray("Sorted array", array); int index = Arrays.binarySearch(array, 1); System.out.println("Didn't find 1 @ " + index); int newIndex = -index - 1; array = insertElement(array, 1, newIndex); printArray("With 1 added", array); } ... Read More
You can get the size of a directory with the help of FileUtils.sizeofDirectory(File Name) method of FileUtils class.Exampleimport java.io.File; import org.apache.commons.io.FileUtils; public class Main { public static void main(String[] args) { long size = FileUtils.sizeOfDirectory(new File("C:/Windows")); System.out.println("Size: " + size + " bytes"); } }OutputSize: 2048 bytes