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Object Oriented Programming Articles
Page 291 of 589
How 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
Read MoreConvert array to generic list with Java Reflections
An array can be converted into a fixed size list using the java.util.Arrays.asList() method. This method is basically a bridge between array based AP!’s and collection based API’s.A program that demonstrates the conversion of an array into a generic list is given as follows −Exampleimport java.util.Arrays; import java.util.Collections; import java.util.List; public class Demo { public static void main(String[] args) { String str[] = new String[]{"apple", "orange", "mango", "guava", "melon"}; List list = Arrays.asList(str); System.out.println("The list is: " + list); } }The output of the above program is as follows ...
Read MoreDemonstrate getting the immediate superclass information in Java
The immediate superclass information of any entity such as an object, class, primitive type, interface etc. can be obtained using the method java.lang.Class.getSuperclass().A program that demonstrates this is given as follows −Examplepackage Test; import java.lang.*; class Class1{ } class Class2 extends Class1{ } public class Demo { public static void main(String args[]) { Class1 obj1 = new Class1(); Class2 obj2 = new Class2(); Class c; c = obj2.getClass(); ...
Read MoreGet the declared method by name and parameter type in Java
The declared method can be obtained by name and parameter type by using the java.lang.Class.getDeclaredMethod() method. This method takes two parameters i.e. the name of the method and the parameter array of the method.The getDeclaredMethod() method returns a Method object for the method of the class that matches the name of the method and the parameter array that are the parameters.A program that gets the declared method by name and parameter type using the getDeclaredMethod() method is given as follows −Examplepackage Test; import java.lang.reflect.*; public class Demo { public String str; private Integer func1() { ...
Read MoreCheck whether String is an interface or class in Java
The method java.lang.Class.isInterface() is used to find if String is an interface or class in Java. This method returns true if String is an interface, otherwise it returns false.A program that demonstrates this is given as follows −Examplepackage Test; import java.lang.*; public class Demo { public static void main(String[] args) { Class c = String.class; boolean interfaceFlag = c.isInterface(); System.out.println("This is an Interface? " + interfaceFlag); } }OutputThis is an Interface? falseNow let us understand the above program.The isInterface() method is used to find if String is an interface ...
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