Java Articles - Page 178 of 440

A LinkedList is a data structure that contains a group of nodes connected in a sequential manner with a pointer. A LinkedList can behave as a dynamic array and it allocates space for each element separately in its own block of memory called a Node. Each node contains two fields, a "data" field to store an element type the list holds and a "next" field which is a pointer used to link one node to the next node.We can iterate the elements of a LinkedList in three ways in Java.Using IteratorWe can iterate the elements of a LinkedList through the Iterator class.Exampleimport java.util.*; ... Read More

A JTextField is a subclass of JTextComponent class and it is one of the most important components that allow the user to input text value in a single-line format. A JTextField class will generate an ActionListener interface when we trying to enter some input inside it. The important methods of a JTextField class are setText(), getText(), setBorder(), setEnabled(),  etc. We can add padding to a JTextField using the setMargin(Insets s) of JTextComponent class.Syntaxpublic void setMargin(Insets m)Exampleimport java.awt.*; import java.awt.event.*; import javax.swing.*; public class JTextfieldPaddingTest extends JFrame {    private JTextField jtf;    public JTextfieldPaddingTest() {       jtf = new JTextField("Welcome to Tutorials Point"); ... 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.We can set the color to alternate rows of JTable by overriding the prepareRenderer() method of JTable class.Syntaxpublic Component prepareRenderer(TableCellRenderer renderer, int row, int column)Exampleimport java.awt.*; import java.awt.event.*; import javax.swing.*; import javax.swing.table.*; public class AlternateRowColorTableTest extends JFrame {    public AlternateRowColorTableTest() {       setTitle("AlternateRowColorTable Test");       JTable table = new JTable(new Object[][] {{"115", "Ramesh"}, {"120", "Adithya"}, {"125", "Jai"}, {"130", "Chaitanya"}, ... Read More

A HashSet implements Set interface which does not allow duplicate values. A HashSet is not synchronized and is not thread-safe. When we can add any duplicate element to a HashSet, the add() method returns false and does not allow to add a duplicate element to HashSet. Syntax public class HashSet extends AbstractSet implements Set, Cloneable, Serializable In the below example, we can implement a Custom HashSet. Example import java.util.*; public class CustomHashSetTest extends AbstractSet { private HashMap map = null; private static final Object tempObject = new Object(); public CustomHashSetTest() { map = new HashMap(); ... Read More

A Locale class is used to perform locale operations and supply locale information to the user. A Locale is defined as a set of parameters that represents a geographical location or place where some operation occurs. The important methods of Locale class are getAvailableLocales(), getCountry(), getDefault(), getDisplayLanguage(), getDisplayCountry(), getUnicodeLocaleKeys() etc. The Locale class uses the following constructors − Locale(String L)− Initializes locale from the language code passed as an argument. Locale(String L, String C) − Initializes locale from the language, country code passed as arguments. Locale(String L, String C, String V) − Initializes locale from the language, country, variant passed as arguments. Example import java.text.SimpleDateFormat; import java.util.Locale; public ... Read More

A thread-safe class is a class that guarantees the internal state of the class as well as returned values from methods, are correct while invoked concurrently from multiple threads. The collection classes that are thread-safe in Java are Stack, Vector, Properties, Hashtable, etc. Stack The Stack class in Java implements the stack data structure that is based on the principle of LIFO. So, the Stack class can support many operations such as push, pop, peek, search, empty, etc. Example import java.util.*; public class StackTest { public static void main (String[] args) { Stack stack = new Stack(); ... Read More

A Java class file has a ".class" extension and contains the Java bytecode. This class file can be executed by the Java Virtual Machine (JVM). A  ".class" file is created as a result of successful compilation by the Java compiler from the ".java" file. Each class in the .java file is compiled into a separate class file if the ".java " file has more than one class.Exampleclass A {    A() {       System.out.println("This is class A");    } } class B {    B() {       System.out.println("This is class B");    } } class C { ... Read More

When a value is assigned to a variable that is less than the minimum allowed value for that variable, then an underflow occurs. There is no exception thrown by the JVM if an underflow occurs in Java and it is the responsibility of a programmer to handle the underflow conditions.Examplepublic class UnderlowTest {    public static void main(String[] args) {       int num1 = -2147483648;       int num2 = -1;       System.out.println("Number 1: " + num1);       System.out.println("Number 2: " + num2);       long sum = (long)num1 + (long)num2;     ... Read More

A JTable provides a very flexible possibility to create and display tables. The TableModel interface defines methods for objects that specify the contents of a table. The AbstractTableModel class is typically extended to provide a custom implementation of a model table. A JTable class provides the ability to edit tables using the method setCellEditor() allows an object of the TableCellEditor interface.We can filter a table using the setRowFilter() method of TableRowSorter class.Exampleimport java.awt.*; import java.awt.event.*; import java.util.regex.*; import javax.swing.*; import javax.swing.table.*; public class FilterTableTest extends JFrame {    private JTable table;    private TableModel model;    public FilterTableTest() {       setTitle("FilterTable Test");       ... Read More

No, the "this" keyword cannot be used to refer to the static members of a class. This is because the “this” keyword points to the current object of the class and the static member does not need any object to be called. The static member of a class can be accessed directly without creating an object in Java. Example public class StaticTest { static int a = 50; static int b; static void show() { System.out.println("Inside the show() method"); b = a + 5; ... Read More