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When you are working with strings in Java, you may want to keep only the alphabetic characters (A-Z, a-z) and remove everything else, like numbers, punctuation, and symbols. Java gives you multiple ways to do this for different cases or scenarios. Removing non-alphabetical characters from a string There are different methods, and they are - Using split() method Using replaceAll() method ... Read More
In this article, we will learn how to convert a JSON string to a Java object using the json.simple library. JSON stands for JavaScript Object Notation. It's a simple format that stores data in key-value pairs. It is used for sharing data between a server and a web app. To learn more about JSON, you can refer to the JSON tutorial. In Java, we can use a library called json.simple to handle JSON data. So, using this, we can easily convert a JSON string into a Java object. Why Convert JSON String to Java Object? There are many reasons to ... Read More
In this article, we will learn how to construct a JSON object from a subset of another JSON object in Java. If you are not familiar with JSON and its usage in Java, you can refer to our JSON Overview tutorial. JSON Object From a Subset of Another Object There is more than one way to construct a JSON object from a subset of another JSON object in Java. Some of the popular libraries that we can use are - Using org.json library Using Gson library Using ... Read More
In this article, we will learn about the differences between a MouseListener and a MouseMotionListener in Java. We can implement a MouseListener interface when the mouse is stable while handling the mouse event, whereas we can implement a MouseMotionListener interface when the mouse is in motion while handling the mouse event. Mouse Listener A MouseListener is fired when we press, release or click (press followed by release) a mouse button (left or right button) at the source object or position the mouse pointer at (enter) and away (exit) from the source object. Abstract Methods A MouseListener interface declares the following five ... Read More
A JTextField is a child class of the JTextComponent class through which a single line of text can be edited. Cut, copy, and paste operations of the JTextField component can be implemented using the cut(), copy(), and paste() methods. These are built-in methods in the JTextField class. built-in methodsJTextField class The Cut Operation Cutting involves removing selected text from the JTextField and placing it on the clipboard. Method Declaration: public void cut() { textField.cut(); } The Copy Operation Copying places a copy of the selected text on the clipboard without removing it from the JTextField. Method ... Read More
In this article, we will learn about the importance of the FocusListener interface in Java. In Java, the FocusListener Interface plays an important role in making GUIs interactive and responsive. It enables the developer to monitor and respond to changes in focus in a Java-based application. FocusListener The focus events are generated whenever a component gains or loses keyboard focus. The Objects representing focus events are created from the FocusEvent Class. The corresponding listener interface for the FocusEvent class is the FocusListener interface. Each listener for FocusEvent can implement the FocusListener interface. Syntax The following is the syntax of the ... Read More
Yes, the namespace can be nested in C++. We can define one namespace inside another namespace. This makes it easier for developers to design a more structured and hierarchical format for their code. Syntax The following is the syntax as below : namespace namespace_name1 { // code declarations namespace namespace_name2 { // code declarations } } You can access members of a nested namespace by using resolution operators as follows: // to access members of namespace_name2 ... Read More
In C++, both pointers and references are used to access and manipulate memory. But they behave differently. This guide explains each with simple words and examples. We understand the topic by learning how each is declared, used, and what differences exist between them. What are C++ Pointers? The pointers are used to store the address of a variable. We can change what they pointing to, and also can assign NULL to them. A pointer is similar to a signpost that contains the memory address of another variable, and you can directly access or change the variable by its address. Syntax ... Read More
In C++, the reference variable is an alternate name of already existing variable. It cannot be changed to refer another variable and should be initialized at the time of declaration and cannot be NULL. The operator '&' is used to declare reference variable. Reference variables are commonly used for parameter passing in functions, returning values, and aliasing existing variables. Syntax Following is the syntax for the reference variable in c++: datatype &refer_var = variable_name; Here, datatype − The datatype of variable like int, char, float etc. variable_name − This is ... Read More
LinkedList and LinkedHashSet are two important classes of Java's Collection framework. They are used to store groups of items, but they work in different ways and have their own unique features. What is a LinkedList in Java? Java LinkedList is a linear data structure that is used to store the same type of elements. It is a part of the Java Collections Framework, and it implements the List as well as the Deque interfaces. It has a dynamic size, which means it can grow and shrink as needed. Example The following is an example of how we write code for ... Read More