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Java Articles
Page 106 of 450
What 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
Read MoreHow to schedule tasks in Java to run for repeated fixed-rate execution, beginning after the specified delay
One of the methods of the Timer class is void scheduleAtFixedRate(TimerTask task, long delay, long period). This method schedules the specified task for repeated fixed-rate execution, beginning after the specified delay.In fixed-rate execution, each execution is scheduled with respect to the scheduled run time of the initial execution. Fixed-rate execution is apt for repetitive activities that are respond to absolute time. Likewise, fixed-rate execution is appropriate for scheduling multiple repeating timer tasks that must remain in sync.Declaration − The java.util.Time.scheduleAtFixedRate(TimerTask task, long delay, long period) method is declared as follows −public void scheduleAtFixedRate(TimerTask task, long delay, long period)Here, task is ...
Read MoreDetermining If an Object Is an Array in Java
In order to determine if an object is an Object is an array in Java, we use the isArray() and getClass() methods.The isArray() method checks whether the passed argument is an array. It returns a boolean value, either true or falseSyntax - The isArray() method has the following syntax -Array.isArray(obj)The getClass() method method returns the runtime class of an object. The getClass() method is a part of the java.lang.Object class.Declaration − The java.lang.Object.getClass() method is declared as follows −public final Class getClass()The getClass() method acts as the intermediate method which returns an runtime class of the object, which enables the terminal ...
Read MoreGet the Component Type of an Array Object in Java
In order to get the component type of an Array Object in Java, we use the getComponentType() method. The getComponentType() method returns the Class denoting the component type of an array. If the class is not an array class this method returns null.Declaration − The java.lang.Class.getComponentType() method is declared as follows -public Class getComponentType()Let us see a program to the get the component type of an Array Object in Java -Examplepublic class Example { public static void main(String[] args) { int[] array = new int[] {1, 2, 3}; // obtain the Class of ...
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