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Object Oriented Programming Articles
Page 290 of 589
Get the list of all the public methods in Java
A list of all the public methods of a class or interface that is represented by an object are provided using the method java.lang.Class.getMethods(). The public methods include that are declared by the class or interface and also those that are inherited by the class or interface.Also, the getMethods() method returns a zero length array if the class or interface has no public methods or if a primitive type, array class or void is represented in the Class object.A program that demonstrates this is given as follows −Exampleimport java.lang.reflect.Method; public class Main { public static void main(String[] argv) throws ...
Read MoreDisplay the package name of a class in Java
The package for a class can be obtained using the java.lang.Class.getPackage() method with the help of the class loader of the class. If there is no package object created by the class loader of the class, then null is returned.A program that demonstrates this is given as follows −Exampleimport java.util.Date; public class Main { public static void main(String[] args) { Date d = new Date(); Package p = d.getClass().getPackage(); String pName = p.getName(); System.out.println("The package name is: " + pName); } }OutputThe package name is: java.utilNow ...
Read MoreGenerate Random Long type numbers in Java
In order to generate Random long type numbers in Java, we use the nextLong() method of the java.util.Random class. This returns the next random long value from the random generator sequence.Declaration − The java.util.Random.nextLong() method is declared as follows −public long nextLong()Let us see a program to generate random long type numbers in Java −Exampleimport java.util.Random; public class Example { public static void main(String[] args) { Random rd = new Random(); // creating Random object System.out.println(rd.nextLong()); // displaying a random long value } }Output-4787108556148621714Note - The output may vary on Online compilers.
Read MoreWhat would getPackage() return for a class in unnamed package in Java?
The package for a class can be obtained using the java.lang.Class.getPackage() method with the help of the class loader of the class.The getPackage() method returns null for a class in unnamed package. A program that demonstrates this is given as follows −Exampleclass Class1 { public class Main { public static void main(String[] argv) throws Exception { Class c = Class1.class; System.out.println(c.getPackage()); } }OutputnullNow let us understand the above program.The getPackage() method is used to obtain the package for the class. However, the getPackage() method returns null for the class ...
Read MoreCheck for the availability of a package in Java
The availability can be checked using the method java.lang.Class.forName(). The class object associated with the class with the given string name can be returned using the method java.lang.Class.forName(String name, boolean initialize, ClassLoader loader), using the class loader that is used to load the class.A program that demonstrates this is given as follows −Examplepublic class Main { public static void main(String args[]) { System.out.println(Availability("java.lang.String")); } public static boolean Availability(String name) { boolean flag = false; try { Class.forName(name, false, null); flag ...
Read MoreGet the unqualified name of a class in Java
A qualified class name in Java contains the package that the class originated from. In contrast to this, the unqualified class name contains only the class name without any package information. A program that gets the unqualified name of a class is given as follows:Examplepublic class Demo { public static void main(String[] argv) throws Exception { Class c = java.util.ArrayList.class; String className = c.getName(); System.out.println("The qualified class name is: " + className); if (className.lastIndexOf('.') < 0) { className = className.substring(className.lastIndexOf('.') + 1); ...
Read MoreGet the fully-qualified name of a class in Java
A fully-qualified class name in Java contains the package that the class originated from. An example of this is java.util.ArrayList. The fully-qualified class name can be obtained using the getName() method.A program that demonstrates this is given as follows −Examplepublic class Demo { public static void main(String[] argv) throws Exception { Class c = java.util.ArrayList.class; String className = c.getName(); System.out.println("The fully-qualified name of the class is: " + className); } }OutputThe fully-qualified name of the class is: java.util.ArrayListNow let us understand the above program.The getName() method is used to ...
Read MoreUsing reflection to check array type and length in Java
The array type can be checked using the java.lang.Class.getComponentType() method. This method returns the class that represents the component type of the array. The array length can be obtained in int form using the method java.lang.reflect.Array.getLength().A program that demonstrates this is given as follows −Exampleimport java.lang.reflect.Array; public class Demo { public static void main (String args[]) { int[] arr = {6, 1, 9, 3, 7}; Class c = arr.getClass(); if (c.isArray()) { Class arrayType = c.getComponentType(); System.out.println("The array is of type: " ...
Read MoreList the Interfaces That a Class Implements in Java
The interfaces that are implemented by a class that is represented by an object can be determined using the java.lang.Class.getInterfaces() method. This method returns an array of all the interfaces that are implemented by the class.A program that demonstrates this is given as follows −Examplepackage Test; import java.lang.*; import java.util.*; public class Demo { public static void main(String[] args) { listInterfaces(String.class); } public static void listInterfaces(Class c) { System.out.println("The Class is: " + c.getName()); Class[] interfaces = c.getInterfaces(); System.out.println("The Interfaces are: " + Arrays.asList(interfaces)); ...
Read MoreCreate and demonstrate an immutable collection in Java
In order to create and demonstrate an immutable collection in Java, we use the unmodifiableCollection() method. This method returns an unmodifiable and immutable view of the collection.Declaration − The java.util.Collections.unmodifiableCollection() method is declared as follows -public static Collection unmodifiableCollection(Collection
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