Java Articles - Page 181 of 440

This article will discuss "how to check the memory used by a program" in Java, including a brief introduction of the process for calculation and an appropriate example that correctly checks the memory usage by the program. Understanding Memory Usage in Java Programs A Java code that takes a long time to execute, makes heavy use of dynamic memory. In such scenarios,  we may end up with Out-of-Memory errors (due to a memory shortage of the heap space). We can calculate the memory space (heap) used by a Java program using the methods provided by the Runtime class.If the heap space is ... Read More

SerialVersionUIDThe SerialVersionUID must be declared as a private static final long variable in Java. This number is calculated by the compiler based on the state of the class and the class attributes. This is the number that will help the JVM to identify the state of an object when it reads the state of the object from a file.The SerialVersionUID can be used during deserialization to verify that the sender and receiver of a serialized object have loaded classes for that object that are compatible w.r.t serialization. If the deserialization object is different than serialization, then it can throw an InvalidClassException.If the serialVersionUID is ... Read More

This article explains the different ways of calling the garbage collector (GC) in Java. It also includes a brief introduction to garbage collection, various calling approaches, and relevant examples. Garbage Collection (GC) in Java In Java, the garbage collection is carried out by a daemon thread called the Garbage Collector (GC). Instead of waiting until the Java Virtual Machine (JVM) runs a garbage collector, we can request the JVM to run the garbage collector. There is no guarantee that the JVM will accept our request. In Java, we can call the garbage collector (GC) manually in "two ways", which ... Read More

An invokeLater() method is a static method of the SwingUtilities class and it can be used to perform a task asynchronously in the AWT Event dispatcher thread. The SwingUtilities.invokeLater() method works like SwingUtilities.invokeAndWait() except that it puts the request on the event queue and returns immediately. An invokeLater() method does not wait for the block of code inside the Runnable referred by a target to execute.Syntaxpublic static void invokeLater(Runnable target)Exampleimport java.awt.*; import java.awt.event.*; import javax.swing.*; public class InvokeLaterTest extends Object {    private static void print(String msg) {       String name = Thread.currentThread().getName();       System.out.println(name + ": " + msg);    }   ... Read More

A JButton is a subclass of AbstractButton and it can be used for adding platform-independent buttons to a GUI application. A JButon can generate an ActionListener interface when the button is pressed or clicked, it can also generate the MouseListener and KeyListener interfaces. We can implement the rollover effect when the mouse moves over a JButton by overriding the mouseEntered() method of the MouseListener interface.Syntaxvoid mouseEntered(MouseEvent e)Exampleimport java.awt.*; import java.awt.event.*; import javax.swing.*; public class RollOverButtonTest extends JFrame {    private JButton button;    public RollOverButtonTest() {       setTitle("RollOverButton Test");       button = new JButton("Rollover Button");       button.addMouseListener(new MouseAdapter() {     ... Read More

This article explains several strategies to avoid deadlock in Java, including a brief introduction to deadlock, strategies, and respective examples. Deadlock in Java In case of multi-threading, a deadlock is a programming situation where two or more threads are holding resources needed by other threads and are blocked forever, waiting for each other (to release the required resource). A deadlock condition will occur with at least two threads and two or more resources.How To Avoid Deadlock in Java? Following is a list of strategies to avoid the deadlock in Java: ... Read More

A yield() method is a static method of Thread class and it can stop the currently executing thread and will give a chance to other waiting threads of the same priority. If in case there are no waiting threads or if all the waiting threads have low priority then the same thread will continue its execution. The advantage of yield() method is to get a chance to execute other waiting threads so if our current thread takes more time to execute and allocate processor to other threads. Syntax public static void yield() Example class MyThread extends Thread { public void run() { ... Read More

Yes, we can define multiple methods in a class with the same name. But if we have two methods with the same name, the compiler should be able to differentiate between the two methods. Therefore, in Java, "we can define multiple methods" with the same name in a single class, as long as each method has a different set of parameters. When we invoke a method, the compiler executes the respective body (code) based on the arguments passed.This concept is known as method overloading. Method Overloading in Java In Java, method overloading is a type of compile-time polymorphism. Polymorphism is one ... Read More

A JTable is a subclass of JComponent class and it can be used to create a table with information displayed in multiple rows and columns. When a value is selected from a JTable, a TableModelEvent is generated, which is handled by implementing a TableModelListener interface.In general, a user can select the rows and columns manually in a JTable, we can also select different cells of a JTable programmatically using setRowSelectionInterval() and setColumnSelectionInterval() methods of JTable class.Exampleimport java.awt.*; import java.awt.event.*; import javax.swing.*; public class JTableCellSelectionTest extends JFrame {    private JTable table;    public JTableCellSelectionTest() {       setTitle("JTableCellSelection Test");       Object[][] data = ... Read More

The article will explain the use of object cloning in Java and provide an appropriate example to clarify the problem. What is the Object Cloning in Java? In Java, object cloning is a way to create an exact copy of an object. We can use the clone() method provided by the Object class to create a clone of an object. When an object is cloned, a new instance of the same class is created, and the fields of the original object are copied to the new object. The Cloneable interface must be implemented by a class whose object is ... Read More