Java Articles - Page 620 of 745

A Singleton pattern states that a class can have a single instance and multiple instances are not permitted to be created. For this purpose, we make the constructor of the class a private and return a instance via a static method. But using serialization, we can still create multiple instance of a class. See the example below −Example - Breaking Singleton Live Demoimport java.io.ByteArrayInputStream; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.io.ObjectInputStream; import java.io.ObjectOutputStream; import java.io.Serializable; public class Tester{    public static void main(String[] args)    throws ClassNotFoundException, IOException{       A a = A.getInstance();       A b ... Read More

A Singleton pattern states that a class can have a single instance and multiple instances are not permitted to be created. For this purpose, we make the constructor of the class a private and return a instance via a static method. But using reflection, we can still create multiple instance of a class by modifying the constructor scope. See the example below −Example - Breaking Singleton Live Demoimport java.io.Serializable; import java.lang.reflect.Constructor; import java.lang.reflect.InvocationTargetException; public class Tester {    public static void main(String[] args) throws    InstantiationException, IllegalAccessException,    IllegalArgumentException, InvocationTargetException{       A a = A.getInstance();     ... Read More

A Singleton pattern states that a class can have a single instance and multiple instances are not permitted to be created. For this purpose, we make the constructor of the class a private and return a instance via a static method. But using reflection, we can still create multiple instance of a class by modifying the constructor scope. See the example below −Example - Breaking Singleton Live Demoimport java.io.Serializable; import java.lang.reflect.Constructor; import java.lang.reflect.InvocationTargetException; public class Tester {    public static void main(String[] args) throws    InstantiationException, IllegalAccessException,    IllegalArgumentException, InvocationTargetException{       A a = A.getInstance();     ... Read More

A Singleton pattern states that a class can have a single instance and multiple instances are not permitted to be created. For this purpose, we make the constructor of the class a private and return a instance via a static method. But using cloning, we can still create multiple instance of a class. See the example below −Example - Breaking Singletonpublic class Tester{    public static void main(String[] args)    throws CloneNotSupportedException {       A a = A.getInstance();       A b = (A)a.clone();       System.out.println(a.hashCode());       System.out.println(b.hashCode());    } } ... Read More

A Singleton pattern states that a class can have a single instance and multiple instances are not permitted to be created. For this purpose, we make the constructor of the class a private and return a instance via a static method. But using cloning, we can still create multiple instance of a class. See the example below −Example - Breaking Singletonpublic class Tester{    public static void main(String[] args)    throws CloneNotSupportedException {       A a = A.getInstance();       A b = (A)a.clone();       System.out.println(a.hashCode());       System.out.println(b.hashCode());    } } ... Read More

If a object is no more referenced by a live reference then it becomes eligible for garbage collection. See the example below −Examplepublic class Tester{    public static void main(String[] args) {       test();    }    public static void test(){       A a = new A();    } } class A {}When test() method complete execution, the a object is no more referenced and is eligible for garbage collection. Java garbage collector will deallocate the object when it runs.To prevent garbage collection, we can create a static reference to an object and then ... Read More

If a object is no more referenced by a live reference then it becomes eligible for garbage collection. See the example below −Examplepublic class Tester{    public static void main(String[] args) {       test();    }    public static void test(){       A a = new A();    } } class A {}When test() method complete execution, the a object is no more referenced and is eligible for garbage collection. Java garbage collector will deallocate the object when it runs.To prevent garbage collection, we can create a static reference to an object and then ... Read More

To find the occurrence of each character in a string we can use the Map utility of Java. In Map a key cannot be duplicated so make each character of the string a key of Map and provide the initial value corresponding to each key as 1 if this character is not inserted in Map before. Now when a character repeats during insertion as a key in Map increases its value by one. Continue this for each character until all characters of the string get inserted. Problem Statement Write a program in Java to check the occurrence of each character in ... Read More

To find the occurrence of each character in a string we can use the Map utility of Java. In Map a key cannot be duplicated so make each character of the string a key of Map and provide the initial value corresponding to each key as 1 if this character is not inserted in Map before. Now when a character repeats during insertion as a key in Map increases its value by one. Continue this for each character until all characters of the string get inserted. Problem Statement Write a program in Java to check the occurrence of each character in ... Read More

Java is a high-level programming language originally developed by Sun Microsystems and released in 1995. Java runs on a variety of platforms, such as Windows, Mac OS, and the various versions of UNIX. .NET framework is a computer software framework invented by Microsoft. It runs on Microsoft Windows OS (Operating Systems). It provides user interface, data access, database connectivity, cryptography, web application development, etc. Languages Java supports only Java patterns. .NET supports multiple languages such as VB.NET, C#, F#, etc. Platforms Java is platform independent and it can run on Windows, Linux and Mac OS. .NET works on Windows. Runtime ... Read More