Article Categories
- All Categories
-
Data Structure
-
Networking
-
RDBMS
-
Operating System
-
Java
-
MS Excel
-
iOS
-
HTML
-
CSS
-
Android
-
Python
-
C Programming
-
C++
-
C#
-
MongoDB
-
MySQL
-
Javascript
-
PHP
-
Economics & Finance
Articles by Vikyath Ram
Page 6 of 10
Generating random numbers in Java
We can generate random numbers using three ways in Java.Using java.util.Random class − Object of Random class can be used to generate random numbers using nextInt(), nextDouble() etc. methods.Using java.lang.Math class − Math.random() methods returns a random double whenever invoked.Using java.util.concurrent.ThreadLocalRandom class − ThreadLocalRandom.current().nextInt() method and similar othjer methods return a random numbers whenever invoked.Exampleimport java.util.Random; import java.util.concurrent.ThreadLocalRandom; public class Tester { public static void main(String[] args) { generateUsingRandom(); generateUsingMathRandom(); generateUsingThreadLocalRandom(); } private static void generateUsingRandom() { Random random = new Random(); ...
Read MoreFlow control in a try catch finally in Java
A method catches an exception using a combination of the try and catch keywords. A try/catch block is placed around the code that might generate an exception. Code within a try/catch block is referred to as protected code, and the syntax for using try/catch looks like the following −Syntaxtry { // Protected code } catch (ExceptionName e1) { // Catch block }The code which is prone to exceptions is placed in the try block. When an exception occurs, that exception occurred is handled by catch block associated with it. Every try block should be immediately followed either by ...
Read Morefinal local variable in Java
Local VariableLocal variables are declared in methods, constructors, or blocks.Local variables are created when the method, constructor or block is entered and the variable will be destroyed once it exits the method, constructor, or block.Access modifiers cannot be used for local variables.Local variables are visible only within the declared method, constructor, or block.Local variables are implemented at stack level internally.There is no default value for local variables, so local variables should be declared and an initial value should be assigned before the first use.final Local Variablefinal is the only allowed access modifier for local variables.final local variable is not required ...
Read MoreFinal static variables in Java
Final Static VariablesClass variables also known as static variables are declared with the static keyword in a class, but outside a method, constructor or a block.There would only be one copy of each class variable per class, regardless of how many objects are created from it.Static variables are normally declared as constants using the final keyword. Constants are variables that are declared as public/private, final, and static. Constant variables never change from their initial value.Static variables are stored in the static memory, mostly declared as final and used as either public or private constants.Static variables are created when the program ...
Read MoreFind free disk space using Java
java.io.File class provides following useful methods to figure out the free disk space available.Sr.No.Method & Description1public long getFreeSpace()Returns the number of unallocated bytes in the partition named by this abstract path name.2public long getTotalSpace()Returns the size of the partition named by this abstract pathname.3public long getUsableSpace()Returns the number of bytes available to this virtual machine on the partition named by this abstract pathname.Following example showcases the use of above methods.Example Finalimport java.io.File; import java.text.NumberFormat; public class Tester { public static void main(String[] args) { NumberFormat numberFormat = NumberFormat.getInstance(); numberFormat.setMaximumFractionDigits(2); ...
Read MoreFactory method to create Immutable Map in Java SE 9
With Java 9, new factory methods are added to Map interface to create immutable instances. These factory methods are convenience factory methods to create a collection in less verbose and in concise way.Old way to create collectionsExampleimport java.util.Collections; import java.util.HashMap; import java.util.Map; public class Tester { public static void main(String []args) { Map map = new HashMap(); map.put("A", "Apple"); map.put("B", "Boy"); map.put("C", "Cat"); Map readOnlyMap = Collections.unmodifiableMap(map); System.out.println(readOnlyMap); try { readOnlyMap.remove(0); ...
Read MoreExternalizable Interface in Java
Externalization is used whenever we need to customize serialization mechanism. If a class implements an Externalizable interface then, object serialization will be done using writeExternal() method. Whereas at receiver's end when an Externalizable object is a reconstructed instance will be created using no argument constructor and then the readExternal() method is called.If a class implements only Serializable interface object serialization will be done using ObjectoutputStream. At the receiver's end, the serializable object is reconstructed using ObjectInputStream.Below example showcases usage of Externalizable interface.Exampleimport java.io.Externalizable; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.io.ObjectInput; import java.io.ObjectInputStream; import java.io.ObjectOutput; import java.io.ObjectOutputStream; public class ...
Read MoreDifference between ArrayList and CopyOnWriteArrayList in Java
Following are the notable differences between ArrayList and CopyOnWriteArrayList classes in Java. ArrayListCopyOnWriteArrayListSynchronizedArrayList is not synchronized.CopyOnWriteArrayList is synchronized.Thread SafeArrayList is not thread safe.CopyOnWriteArrayList is thread safe.Iterator typeArrayList iterator is fail-fast and ArrayList throws ConcurrentModificationException if concurrent modification happens during iteration.CopyOnWriteArrayList is fail-safe and it will never throw ConcurrentModificationException during iteration. The reason behind the it that CopyOnWriteArrayList creates a new arraylist every time it is modified.Remove OpearationArrayList iterator supports removal of element during iteration.CopyOnWriteArrayList.remove() method throws exception if elements are tried to be removed during iteration.PerformanceArrayList is faster.CopyOnWriteArrayList is slower than ArrayList.Since Java Version1.21.5Exampleimport java.util.Iterator; import java.util.concurrent.CopyOnWriteArrayList; public class Tester { ...
Read MoreHow Can MySQL operator precedence affect result set?
MySQL follows operator precedence and it has the following list of operators, having the same precedence which is on the same line −INTERVAL BINARY, COLLATE ! - (unary minus), ~ (unary bit inversion) ^ *, /, DIV, %, MOD -, + & | =, , >=, >,
Read MoreHow can we generate the same sequence of random numbers in MySQL?
When invoked with an integer argument, RAND( ) uses that value to seed the random number generator. Each time you seed the generator with a given value, RAND( ) will produce the same sequence of random numbers. Following example will demonstrate it −Examplemysql> Select RAND(1), RAND(1), Rand(1); +---------------------+---------------------+---------------------+ | RAND(1) | RAND(1) | Rand(1) | +---------------------+---------------------+---------------------+ | 0.40540353712197724 | 0.40540353712197724 | 0.40540353712197724 | +---------------------+---------------------+---------------------+ 1 row in set (0.00 sec)
Read More