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Java Articles
Page 106 of 450
Get 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 ...
Read MoreGet the class name for various objects in Java
The getName() method is used to get the names of the entities such as interface, class, array class, void etc. that are represented by the class objects. These names are returned in the form of a string. The getPackage() method gets the package for the given class.A program that gets the class name for various objects is given as follows −Examplepackage Test; import java.io.IOException; import java.util.HashMap; public class Demo { public static void main(String args[]) throws IOException { Object obj = "string"; System.out.println("The class name is: " + obj.getClass().getName()); obj ...
Read MoreGet Canonical Name for a class in Java
The canonical name of a class can be obtained using the java.lang.Class.getCanonicalName() method. This method returns the canonical name of the underlying class and returns null if there is no canonical name for the underlying class.A program that demonstrates the getCanonicalName() method to obtain the canonical name is given as follows −Examplepackage Test; import java.lang.*; public class Demo { public static void main(String[] args) { Demo obj = new Demo(); Class c = obj.getClass(); System.out.println("The canonical name of the underlying Class is: " + c.getCanonicalName()); } }OutputThe canonical name ...
Read MoreUse reflection to create, fill, and display an array in Java
An array is created using the java.lang.reflect.Array.newInstance() method. This method basically creates a new array with the required component type as well as length.The array is filled using the java.lang.reflect.Array.setInt() method. This method sets the required integer value at the index specified for the array.The array displayed using the for loop. 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[] = (int[])Array.newInstance(int.class, 10); int size = Array.getLength(arr); for (int i = 0; i
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