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Object Oriented Programming Articles
Page 479 of 589
New keyword in Java
Yes, it is similar to a new keyword of C++. a new keyword is used to initialize/create an object. See the following example −Employee employee = new Employee();Here new keyword is used to create an object of class Employee.new Employee() invokes the constructor of the class Employee.new keyword can also be used without assigning the object to a reference variable. See the example −String name = new Employee().getName();Here we are creating an object using new keyword and then invoked a method getName() on the object and passed the result to a variable.
Read MoreAdvantages of naming conventions in Java
Following the the best practices while declaring a variable. These best practices maintains code readability, understandability as project code size increases.Variables names should be short or long enough as per the scope. For example, loop counter variable, i is fine whereas employee as loop variable.Specific words should not be used like equals, compare, data.Use meaningful names which can explain the purpose of the variable. For example cnt Vs counter.Don't use _ to declare a variable name, Use camel casing. For example, employeeName is better than employee_name.Each organization has its own syntax specific standards. Follow those rules to maintain consistency ...
Read MoreWhat is runtime polymorphism or dynamic method overloading?
Polymorphism is the ability of an object to take on many forms. The most common use of polymorphism in OOP occurs when a parent class reference is used to refer to a child class object. Method overriding by a subclass is termed as runtime polymorphism. JVM determines the method to be executed at runtime instead of compile time. example class SuperClass { SuperClass get(){ System.out.println("SuperClass"); return this; } } public class Tester extends SuperClass { Tester get(){ System.out.println("SubClass"); return this; } public static void main(String[] args) { SuperClass tester = new Tester(); tester.get(); } } Output SubClass
Read MoreHow do you write a method in Java that can print object in array?
Exampleclass Shape{ private String shapeName; private int numSides; Shape(String shapeName, int numSides){ this.shapeName = shapeName; this.numSides = numSides; } public String toString(){ return shapeName + " has " + numSides + " sides."; } } class ObjectList{ private Object[] list = new Object[10]; private int numElement = 0; public void add(Object next){ list[numElement] = next; numElement++; } @Override public String toString(){ String str=""; int i=0; while(list[i] != null){ str += list[i]+""; i++; } return str; } } public class Driver{ public static void main(String[] args){ ObjectList list = new ObjectList(); Shape square = new Shape("square", 4); Shape hex = new Shape("hexagon", 6); list.add(hex); list.add(square); System.out.println(list); } }
Read MoreImportance of Collectors.flatMapping() method in Java 9?
In Java 9, a new method added to the Collectors class: flatMapping(). It is similar to the Collectors.mapping() method in which the flatMapping() method allows us to handle nested collections. The Collectors.flatMapping() method takes a function to be applied to input elements and a collector to accumulate the elements passed through the function. Unlike the Collectors.mapping() method, the Collectors.flatMapping() method deals with a stream of elements that allows us to get rid of unnecessary intermediary collections.Syntaxpublic static Collector flatMapping(Function
Read MoreImportance of the Collectors.filtering() method in Java 9?
Collectors class is an essential part of the Stream API. In Java 9, a new method: filtering() added to the Collectors class. The Collectors.filtering() method can be used for filtering elements in a stream. It is similar to the filter() method on streams. The filter() method processes the values before they have grouped whereas the filtering() method can be used nicely with the Collectors.groupingBy() method to group the values before the filtering step takes place.Syntaxpublic static Collector filtering(Predicate
Read MoreWhat is a forward reference in JShell in Java 9?
JShell is a command-line tool that allows us to enter Java statements (simple statements, compound statements, or even full methods and classes), evaluates it and prints the result.Forward references are commands that refer to methods, variables, or classes that don't exist in any code we have typed in JShell. As code entered and evaluated sequentially in JShell, these forward references have temporarily unresolved. JShell supports forward references in method bodies, return types, parameter types, variable types, and within a class.In the below code snippet, created a method forwardReference() in Jshell. This method can't be invoked until the variable is declared. ...
Read MoreHow to create JShell instance programmatically in Java 9?
JShell is an interactive tool introduced since Java 9. It is Java's first official REPL tool to create a simple programming environment in the command-line that reads the user's inputs, evaluates it, and prints the result.We can able to create a new JShell instance programmatically in Java language. JShell and its associated APIs can be found under jdk.jshell package. we can get a new instance for JShell by using the static method: create() of JShell class. The eval() method of JShell class used to add an expression to JShell instance. It returns a list of events triggered by the evaluation. ...
Read MoreWhat are the different shortcut keys in JShell in Java 9?
JShell is an interactive tool that allows us to execute the java code and getting immediate results. We quickly evaluate expressions or short algorithms without compiling or build it. We can execute expressions, classes, methods, variables, and etc with the help of the JShell tool.Below are some of the keyboard shortcut keys:Entrance - Validate the lineLeft arrow - Move left in the lineRight arrow - Move right in the lineCtrl-A - Move to the start of the lineCtrl-E- Move to the end of the lineAlt-B - Move left, word by wordAlt-F - Move right, word by wordDelete - Delete characters ...
Read MoreWhat is Project Jigsaw in Java 9?
The primary objective of the Jigsaw project is to introduce the modularity concept to create a module in Java 9 and then applying the same to JDK.Below are some of the benefits of Modularity(Jigsaw)Strong Encapsulation: The modules can access only those parts that can be available for use. Unless the package is explicitly exported into the module-info.java file, public classes in a package can't be public.Clear Dependencies: A module must declare about other modules that they are used through the required clause. The modules are combined in order to create a shorter runtime that can be scaled to comparatively smaller ...
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