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Programming Articles
Page 1638 of 2547
What is the contract between equals() and hashCode() methods in Java?
Every Java object has two very important methods, equals() and hashCode(), and these methods are designed to be overridden according to their specific general contract. Since the Object class is the parent class of every class, the default implementation of the equals() and hashCode() methods is already present in each class. However, we need to override these methods based on the requirement. Let's discuss the contract between equals() and hashCode() methods in Java. But before that, we need to understand these methods. The hashCode() Method The hashCode() method returns an integer value, which is referred to as the hash code value ...
Read MoreInterface variables are static and final by default in Java, Why?
In Java, interfaces are used to achieve abstraction and multiple inheritance. They can contain methods and variables, but there are specific rules about how those members should behave. For example, all variables declared in an interface are public, static, and final by default, even if you don't use these keywords while defining variables. To understand the reason behind it, we first need to understand what static and final mean in Java. What is a Static Variable in Java? The static variables are defined using the static keyword. These variables belong to the class rather than to any specific object, which ...
Read MoreHow to handle the ArrayStoreException (unchecked) in Java?
In Java, ArrayStoreException is a public class that extends the RuntimeException class of the java.lang package. It is thrown by the Java Virtual Machine when a runtime error occurs. Since it is an unchecked exception, it does not require an explicit declaration in a method or a constructor's throws clause. Let's understand why the ArrayStoreException is thrown and how we can avoid it. Reason for ArrayStoreException in Java As mentioned earlier, ArrayStoreException is an unchecked exception, and it can occur when we try to store an object of one type in an array of a different type. Usually, one would ...
Read MoreC++ Program to Implement Double Order Traversal of a Binary Tree
Double Order Traversal Double order traversal means each node in a tree is traversed twice in a particular order. A binary tree is a non-linear data structure where each node contains at most two children (i.e, left and right). Therefore, suppose we have a given binary tree, and the task is to find its double-order traversal. A double order traversal is a tree traversal technique in which every node traverses twice in the following order: Visit the node. Traverse the left subtree. Visit the node. ...
Read MoreC++ Program to Construct an Expression Tree for a given Prefix Expression
What is Expression Tree?An expression tree is a binary tree used to represent expressions. In an expression tree, internal nodes correspond to operators, and each leaf node corresponds to an operand. Let's see an expression and construct a tree for [5 + ((4+3)*2)]. Constructing an Expression TreeOur task is to construct an expression tree from a prefix expression. We have given a character array arr[] representing a prefix expression, so we have to build an expression tree for the expression and then display the infix and postfix expressions of the created tree. Input/Output Scenario Following are the examples to ...
Read MoreHow to set local date/time in a table using LocalDateTime class in Java?
The java.time package of Java provides a class named LocalDateTime is used to get the current value of local date and time. Using this in addition to date and time values, you can also get other date and time fields, such as day-of-year, day-of-week, and week-of-year. Setting the Local time to a column To set the local date and time value to a column in a table. Obtain the LocalDateTime object: You can obtain the LocalDateTime object by invoking the static method now() as: LocalDateTime localDateTime = LocalDateTime.now(); Get the LocalDate and LocalTime objects from the above obtained LocalDateTime as: ...
Read MoreHow can we show a popup menu when the user right-clicks on a JComboBox in Java?
A JComboBox is a Swing component that has a built-in left-click menu. In this article, we will learn how to show a popup menu when the user right-clicks on a JComboBox in Java. What is a JComboBox? A JComboBox is a subclass of the JComponent class that displays a drop-down list and gives users options that they can select only one item at a time. A JComboBox can be editable or read-only. The getSelectedItem() Method A getSelectedItem() method can be used to get the selected or entered item from a combo box. What is a Popup Menu? A popup menu is ...
Read MoreProgram to Find Area of an Ellipse using C++
An ellipse is the locus on all those points in a plane such that the sum of their distance from two fixed points in the plane is constant. Where the fixed point is known as foci, which are sounded by the curve, the fixed line is a directrix, and the constant ratio is the eccentricity of the ellipse. Area of an Ellipse The area of an ellipse is the region enclosed by the ellipse. Which is computed by the following formula: Area = Π∗a∗b Let's discuss the following key points of an ellipse: ...
Read MoreC++ Program to Implement Queue Using Two Stacks
Stack The stack is a linear data structure that follows the Last-In-First-Out (LIFO) operation. Where the element will be added and removed from the top. Following are the stack operations: push (int data): Insertion at top int pop(): Deletion from top Queue The queue is also a linear data structure that follows the First-In-First-Out (FIFO) operation. Where insertions are done at one end (rear) and deletions are done from another end (front). The first element that is entered is deleted first. Following are the stack operations: EnQueue (int data): Insertion at rear end int DeQueue(): Deletion from ...
Read MoreC++ Program to Implement Nearest Neighbour Algorithm
In this article, we will see a C++ program to implement the nearest neighbour algorithm: The nearest neighbour algorithm is a greedy algorithm used to find the approximate solution to the Travelling Salesman Problem (TSP) by computing the minimum cost required to visit all the nodes by traversing across the edges only once. We can implement this algorithm using different data structures like arrays, linked lists, or trees for efficient searching. How Nearest Neighbour Algorithm Works It start at a given point (eg., a city in TSP). Find the nearest unvisited ...
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