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Articles by raja
Page 37 of 38
How can we implement line wrap and word wrap text inside a JTextArea in Java?
A JTextArea is a multi-line text component to display text or allow the user to enter the text and it will generate a CaretListener interface when we are trying to implement the functionality of the JTextArea component. A JTextArea class inherits the JTextComponent class in Java.In the below example, we can implement a JTextArea class with a user can select either word wrap or line wrap checkboxes using the ItemListener interface.Exampleimport javax.swing.*; import java.awt.*; import java.awt.event.*; public class JTextAreaTest { public static void main(String[] args ) { EventQueue.invokeLater(new Runnable() { @Override public void run() { ...
Read MoreWhat is the importance of the GridBagConstraints class in Java?
A GridBagLayout is a very flexible layout manager that allows us to position the components relative to one another using constraints. Each GridBagLayout uses a dynamic rectangular grid of cells with each component occupying one or more cells called its display area. Each component managed by a GridBagLayout is associated with a GridBagConstraints instance that specifies how the component is laid out within its display area. GridBagConstraintsWe can customize a GridBagConstraints object by setting one or more of its public instance variables. These variables specify the component location, size, growth factor, anchor, inset, filling, and padding.gridx: An int value that specifies the leftmost cell that the ...
Read MoreWhat is the importance of SwingUtilities class in Java?
In Java, after swing components displayed on the screen, they can be operated by only one thread called Event Handling Thread. We can write our code in a separate block and can give this block reference to Event Handling thread. The SwingUtilities class has two important static methods, invokeAndWait() and invokeLater() to use to put references to blocks of code onto the event queue.Syntaxpublic static void invokeAndWait(Runnable doRun) throws InterruptedException, InvocationTargetException public static void invokeLater(Runnable doRun)The parameter doRun is a reference to an instance of Runnable interface. In this case, the Runnable interface will not be passed to the constructor of a Thread. The Runnable interface is simply ...
Read MoreWhat are the differences between JFrame and JDialog in Java?
JFrameThe components added to the frame are referred to as its contents, these are managed by the contentPane. To add a component to a JFrame, we must use its contentPane instead.A JFrame contains a window with title, border, (optional) menu bar and user-specified components.A JFrame can be moved, resized, iconified and it is not a subclass of JComponent.By default, JFrame is displayed in the upper-left corner of the screen. To display a frame at a specified location, we can use the setLocation(x, y) method in the JFrame class.Exampleimport java.awt.*; import java.awt.event.*; import javax.swing.*; public class JFrameDemo { public static void main(String s[]) { ...
Read MoreWhy AWT components are heavy-weight while Swing components are light-weight in Java?
AWT stands for Abstract Window ToolKit and it supports Java GUI programming. It is a portable GUI library for Stand-alone Java applications/applets. The AWT provides the connection between our application and the native GUI while Java Swing implements a set of GUI components that build on AWT technology and it can provide a pluggable look and feel. Java Swing is implemented entirely in the Java programming language.First of all, by a heavy-weight, it means the code will take comparatively more time to load and it will consume more System resources. AWT is considered to be heavy-weight because its components are dependent ...
Read MoreWhy the constructor name is same as the class name in Java?
Every class object is created using the same new keyword, so it must have information about the class to which it must create an object. For this reason, the constructor name should be the same as the class name.Exampleclass MyConstructor{ public MyConstructor() { System.out.println("The constructor name should be same as the class name"); } public static void main(String args[]){ MyConstructor mc = new MyConstructor(); } }In the above program, the constructor name should be the same as the class name (MyConstructor).OutputThe constructor name should be same as the class name
Read MoreScope and lifetime of variables in Java?
Instance VariablesA variable which is declared inside a class and outside all the methods and blocks is an instance variable. The general scope of an instance variable is throughout the class except in static methods. The lifetime of an instance variable is until the object stays in memory.Class VariablesA variable which is declared inside a class, outside all the blocks and is marked static is known as a class variable. The general scope of a class variable is throughout the class and the lifetime of a class variable is until the end of the program or as long as the ...
Read MoreHow to implement DoublePredicate using lambda and method reference in Java?
DoublePredicate is a built-in functional interface defined in java.util.function package. This interface can accept one double-valued parameter as input and produces a boolean value as output. DoublePredicate interface can be used as an assignment target for a lambda expression or method reference. This interface contains one abstract method: test() and three default methods: and(), or() and negate().Syntax@FunctionalInterface public interface DoublePredicate { boolean test(double value) }Example of lambda expressionimport java.util.function.DoublePredicate; public class DoublePredicateLambdaTest { public static void main(String args[]) { DoublePredicate doublePredicate = (double input) -> { ...
Read MoreHow to write the comparator as a lambda expression in Java?
A lambda expression is an anonymous method and doesn't execute on its own in java. Instead, it is used to implement a method defined by the functional interface. A lambda expression used with any functional interface and Comparator is a functional interface. The Comparator interface has used when sorting a collection of objects compared with each other.In the below example, we can sort the employee list by name using the Comparator interface.Exampleimport java.util.ArrayList; import java.util.Collections; import java.util.List; class Employee { int id; String name; double salary; public ...
Read MoreWhat is the data type of a lambda expression in Java?
The lambda expressions have a very simple, precise syntax and provide flexibility to specify the datatypes for the function parameters. Its return type is a parameter -> expression body to understand the syntax, we can divide it into three parts.Parameters : These are function method parameters and match with the signature of a function defined in the functional interface. Defining the data-type of parameters is optional but the number of parameters can match with the defined signatures in the interface.Expression Body : This is either a single statement or collection of statements that represent the function definition. Defining the data-type ...
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