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Programming Articles
Page 2330 of 2547
Importance of the parseBoolean() method in Java?
The parseBoolean() method is an important method of a Boolean class. The parseBoolean() is a static method and can parse the String method argument into a Boolean object. The parseBoolean() method of Boolean class returns the boolean represented by the string argument.Syntaxpublic static boolean parseBoolean(String s)Exampleimport java.util.Scanner; public class ParseBooleanMethodTest { public static void main(String[] args) { System.out.print("Are you ready to play cricket(true/false)?"); Scanner scanner = new Scanner(System.in); String str = scanner.nextLine(); scanner.close(); // Convert the user input into boolean boolean answer ...
Read MoreWhat is the importance of a WindowListener interface in Java?
The class which process the WindowEvent needs to be implemented this interface and an object of this class can be registered with a component by using addWindowListener() method.Methods of WindowListener InterfaceThe WindowListener interface defines 7 methods for handling window eventsvoid windowActivated(WindowEvent we) − Invoked when a window is activated.void windowDeactivated(WindowEvent we) − Invoked when a window is deactivated.void windowOpened(WindowEvent we) − Invoked when a window is opened.void windowClosed(WindowEvent we) − Invoked when a window is closed.void windowClosing(WindowEvent we) − Invoked when a window is closing.void windowIconified(WindowEvent we) − Invoked when a window minimized.void windowDeiconfied(WindowEvent we) − Invoked when a window is restored.Syntaxpublic ...
Read MoreCan we override final methods in Java?
Overriding is a one of the mechanisms to achieve polymorphism. This is the case when we have two classes where, one inherits the properties of another using the extends keyword and, these two classes same method including parameters and return type (say, sample).Since it is inheritance. If we instantiate the subclass a copy of superclass’s members is created in the subclass object and, thus both methods are available to the subclass.When we invoke this method (sample) JVM calls the respective method based on the object used to call the method.Overriding final methodsNo, you cannot override final method in java. If ...
Read MoreJava.util.StringJoiner in Java8
This class is used Join a sequence of characters separating using the delimiter.Examplepublic class StringJoinerSample { public static void main(String[] args){ StringJoiner sj = new StringJoiner(", "); sj.add("Krishna"); sj.add("Raju"); sj.add("Satish"); sj.add("Pruthvi"); System.out.println(sj); } }OutputKrishna, Raju, Satish, Pruthvi
Read MoreWhat is the difference between object and reference in java?
A class in a blue print/user defined datatype in java that describes the behavior/state that the object of its type support.Examplepublic class Student { String name "Krishna"; int age = 20; void greet() { System.out.println("Hello how are you"); } }An object is an instance of a class created from it using the new keyword. Once you create an object of a class, using it you can access he members of the class. In the below given code an object of the class Student is created.public class Example { public static void main(String ...
Read MoreCan we serialize static variables in Java?
In Java, serialization is a concept using which we can write the state of an object into a byte stream so that we can transfer it over the network (using technologies like JPA and RMI).But, static variables belong to class therefore, you cannot serialize static variables in Java. Still if you try to do so, the program gets compiled successfully but it raises an exception at the time of execution.In the following java program, the class Student has a static variable and we are trying to serialize and desterilize its object in the another class named ExampleSerialize.Exampleimport java.io.FileInputStream; import java.io.FileOutputStream; ...
Read MoreWhat is a remote interface in java?
A Remote interface is available in the java.rmi package it is a marking/tagging interface, it is used with remote method invocation(RMI).RMI is a mechanism that allows an object residing in one system (JVM) to access/invoke an object running on another JVM.To it is a marking interface, to mark an object of a class remote, you need to implement this interface.To create a remote interface −Create an interface that extends the predefined interface Remote which belongs to the package or, implement the Remote interface with the class, which you need to make remote.Declare all the business methods that can be invoked ...
Read MoreCan we declare the variables of a Java interface private and protected?
Interface in Java is similar to class but, it contains only abstract methods and fields which are final and static.Private fields of an interfaceIf the fields of the interface are private, you cannot access them in the implementing class.If you try to declare the fields of an interface private, a compile time error is generated saying “modifier private not allowed here”.ExampleIn the following Java example, we are trying to declare the field and method of an interface private.public interface MyInterface{ private static final int num = 10; private abstract void demo(); }Compile time errorOn compiling, the above program ...
Read MoreCan we implement one interface from another in java?
No, we cannot implement one interface from another you can just extend it using the extends keyword as −interface ArithmeticCalculations{ public abstract int addition(int a, int b); public abstract int subtraction(int a, int b); } interface MathCalculations implements ArithmeticCalculations{ public abstract double squareRoot(int a); public abstract double powerOf(int a, int b); }Still, if you try to implement one interface from another using the implements keyword. The compiler does not recognize the implements keyword after the name of the interface and throws a compile time error saying “'{' expected”.ExampleIn the following Java program, we have two interfaces ...
Read MoreCan we declare an interface as final in java?
Interface in Java is similar to class but, it contains only abstract methods and fields which are final and static.Since all the methods are abstract you cannot instantiate it. To use it, you need to implement this interface using a class and provide body to all the abstract methods int it.Making an interface final.If you declare a class final cannot extend it. If you make a method final you cannot override it and, if you make a variable final you cannot modify it. i.e. use final with Java entities you cannot modify them further.If you make an interface final, you ...
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