Object Oriented Programming Articles - Page 905 of 915

No, constructor does not have any return type in Java. Constructor looks like method but it is not. It does not have a return type and its name is same as the class name. Mostly it is used to instantiate the instance variables of a class. If the programmer doesn’t write a constructor the compiler writes a constructors on his behalf. Example If you closely observe the declaration of the constructor in the following example it just have the name of the constructor which is similar to class and, the parameters. It does not have any return type. public ... Read More

In this article, we will learn about the character wrapper class and its methods in Java. The Character class is the primitive char type wrapper, providing useful methods for manipulation, classification, and conversion of characters. The Character Wrapper Class The Character class of the java.lang package wraps a value of the primitive datatype char. It offers a number of useful class (i.e., static) methods for manipulating characters. You can create a Character object with the Character constructor. Syntax Character ch = new Character('a'); Various Methods in the Character Class The following are some of the methods used in the ... Read More

Yes, the constructor should always have the same name as the class. Constructor looks like method but it is not. It does not have a return type and its name is same as the class name. Mostly it is used to instantiate the instance variables of a class. If the programmer doesn’t write a constructor the compiler writes a constructors on his behalf. Example Live Demo public class Sample{ public Sample(){ System.out.println("This is a constructor"); } public static void main(String args[]){ Sample obj = new Sample(); } } Output This is a constructor

An abstract cannot be instantiated. Therefore to use an abstract class you need to create another class and extend the abstract class and use it. If a class is final you can’t extend it further. So, you cannot declare a class both final and abstract. Example Still if you try to do so you will get a compile time error saying “illegal combination of modifiers:” final abstract class Demo{ public final void display(){ System.out.println("Hello welcome to tutorialspoint"); } } Output C:\Sample>javac Demo.java Demo.java:1: error: illegal ... Read More

The Number class (abstract) of the java.lang package represents the numeric values that are convertible to primitive types byte, double, float, int, long, and short. Following are the method provided by the Number class of the java.lang package. Sr.No Method & Description 1 byte byteValue() This method returns the value of the specified number as a byte. 2 abstract double doubleValue() This method returns the value of the specified number as a double. 3 abstract float floatValue() This method returns the value of the specified number as a float. ... Read More

The method signature consists of the method name and the parameter list. Example Live Demo public class MethodSignature { public int add(int a, int b){ int c = a+b; return c; } public static void main(String args[]){ MethodSignature obj = new MethodSignature(); int result = obj.add(56, 34); System.out.println(result); } } Output 90 Method ... Read More

Java provides javax.json.Json package which contains classes to read a JSON array:Exampleimport java.io.FileOutputStream; import javax.json.Json; import javax.json.JsonArray; import javax.json.JsonWriter; public class JSONArrayToFile {    public static void main(String args[]) throws Exception {       JsonArray value = Json.createArrayBuilder()          .add(Json.createObjectBuilder()          .add("id", "1001")          .add("Technology", "JavaFX"))          .add(Json.createObjectBuilder()          .add("id", "1002")          .add("Technology", "OpenCV"))          .build();       System.out.println(value);       JsonWriter writer = Json.createWriter(new FileOutputStream("sampleData"));       writer.writeArray(value);       writer.close();    } }Output["JavaFX","HBase","JOGL","WebGL"] After deleting ::["JavaFX","HBase","JOGL"]

The Object class is the superclass of every single class in Java. This position implies that every class in Java, even if a built-in class or function like String or a user-defined one, directly or indirectly inherits from Object. Understanding the Object Class The Object class provides fundamental methods that every Java object inherits. Even if a class does not explicitly extend another class, it implicitly extends Object. Below is a demostration of the same − class Example { //This class implicitly extends to an Object } Why Does Every Class Inherit from ... Read More

You can remove an element from the JSONArray object using the remove() method. This method accepts an integer and removes the element in that particular index.Exampleimport org.json.JSONArray; public class RemoveFromJsonArray {    public static void main(String args[]) throws Exception {       String [] myArray = {"JavaFX", "HBase", "JOGL", "WebGL"};       JSONArray jsArray = new JSONArray();       for (int i=0; i < myArray.length; i++) {          jsArray.put(myArray[i]);      }      System.out.println(jsArray);      jsArray.remove(3);      System.out.println("After deleting ::"+jsArray);    } }Output["JavaFX","HBase","JOGL","WebGL"] After deleting ::["JavaFX","HBase","JOGL"]

In Java Inheritance is a fundamental feature that allows a class to derive properties and behaviors from another class. In Java, not all classes can be subclassed. A final class is a special type of class that cannot be extended.  What is a Final Class in Java? In Java, a class is declared final using the final keyword. The final modifier for finalizing the implementations of classes, methods, and variables. When a class is marked as final, it means − It cannot be extended. All its methods remain unchanged in their ... Read More