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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 More
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 More
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 More
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 ... Read More
In this article, we will learn to set the shortcut key to a JCheckBox in Java. To create a JCheckBox with a keyboard shortcut (Alt + C), we will use Java Swing. When we either click the checkbox with the mouse or press Alt+C, the checkbox toggles, and a message dialog is displayed. We can do this by using the setMnemonic('C') method to assign the shortcut key and an ActionListener to respond to the checkbox selection. What is a JCheckBox? A JCheckBox is a subclass of JToggleButton, and it can be a small box that is either checked or unchecked. When ... Read More
Method overriding works because of the run-time method binding feature in Java. So, if we force the Java compiler to do static binding for a method then we can prevent that method from being overridden in a derived class. Preventing Method Overriding in Java We can prevent method overriding in Java in 3 ways: By declaring a method as "final" in the base class By declaring a method as "static" in the base class By declaring a method as "private" in the base class Final Methods cannot be Overridden ... Read More
A Java program may contain an interface, a variable, a method, a class, and an object. When we execute the program, the operating system allocates some memory to Java Virtual Machine. Then, JVM divides allocated memory into two parts, which are the Heap and the Stack. The values of variables, methods, and classes are stored inside the Heap. And, the reference variables, method names, and classes are stored in the stack. When the Stack becomes full, the JVM throws a StackOverflowError, and when the heap becomes full, it throws an OutOfMemoryError. StackOverflowError in Java A stack is used for the execution of methods. It ... Read More
The Heap Memory and String Constant Pool are two different memory locations in Java where objects are stored during the execution of programs. Both memory areas are managed by the Java Virtual Machine. In this article, we are going to discuss the difference between Heap Memory and String Constant Pool in Java. Heap Memory Heap memory is a runtime data area from which memory for all class instances and arrays is allocated. It is the main memory area used for dynamic memory allocation in Java. Example Creating strings with the new keyword always allocates new memory in the heap. In ... Read More
Yes, we can declare a try-catch block within another try-catch block in Java, this is called nested try-catch block. The try-catch block is used to handle runtime errors that occur during the execution of a program, and the process of handling these errors is called exception handling. The runtime errors or exceptions must be handled in order to maintain the normal flow ofaJava program. Try-Catch Block in Java In a try-catch block, the code that might throw an exception should be placed or written within a try block. The catch block is used to handle the exception that is thrown from ... Read More
In Java, both the length property and the length() method are used to determine the size of data, or we can say they help us to find the number of elements an object contains. However, they are used with different Java objects. The length is an instance variable used for arrays, whereas length() is a method used with String objects. In this article, we are going to discuss the difference between length and length() in Java. The length Property An array is an object that holds a fixed number of values of the same type. Its length variable is used to find the number ... Read More