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Java Articles
Page 441 of 450
Can a Vector contain heterogeneous objects in Java?
Since a vector stores elements in the form of objects, you can store objects of various types (heterogeneous) in it.Example:import java.util.*; class Demo{} public class VectorSample { public static void main(String args[]) { Demo obj = new Demo(); Vector v = new Vector(3, 2); System.out.println("Initial size: " + v.size()); System.out.println("Initial capacity: " + v.capacity()); v.addElement(new Integer(1)); v.addElement(new String("krishna")); v.addElement(new Float(3.5f)); v.addElement(obj); System.out.println("Capacity after four additions: " + v.capacity()); } }
Read MoreWhat does the method add(E element) do in java?
The add(E e) method of the java.util.ArrayList class appends the specified element E to the end of the list.Example:import java.util.ArrayList; public class ArrayListDemo { public static void main(String[] args) { ArrayList arrlist = new ArrayList(5); arrlist.add(15); arrlist.add(20); arrlist.add(25); for (Integer number : arrlist) { System.out.println("Number = " + number); } } }Output:Number = 15 Number = 20 Number = 25
Read MoreHow to synchronize an ArrayList in Java?
The synchronizedList(List list) method of the Collections class accepts a List object and returns a synchronized list backed by the specified list.Example:import java.util.ArrayList; import java.util.Collections; import java.util.LinkedHashSet; import java.util.Set; public class ArrayListSample { public static void main(String[] args){ ArrayList list = new ArrayList(); list.add("JavaFx"); list.add("Java"); list.add("WebGL"); list.add("OpenCV"); Set set = new LinkedHashSet(list); Collections.synchronizedList(list); System.out.println(list); } }Output:[JavaFx, Java, WebGL, OpenCV]
Read MoreHow to sort an ArrayList in Java in ascending order?
You can sort an ArrayList using the sort() method of the Collections class this method accepts a list object as a parameter and sorts the contents of it in ascending order.Example:import java.util.ArrayList; import java.util.Collections; import java.util.LinkedHashSet; import java.util.Set; public class ArrayListSample { public static void main(String[] args) { ArrayList list = new ArrayList(); list.add("JavaFx"); list.add("Java"); list.add("WebGL"); list.add("OpenCV"); Set set = new LinkedHashSet(list); Collections.sort(list); System.out.println(list); } }Output:[Java, JavaFx, OpenCV, WebGL]
Read MoreHow to sort an ArrayList in Java in descending order?
To sort the contents of an ArrayList in descending orderCreate an ArrayList.Sort the contents of the ArrayList using the sort() method of the Collections class.Then, reverse array list using the reverse() method of the Collections class.Example:import java.util.ArrayList; import java.util.Collections; public class ArrayListSample { public static void main(String[] args) { ArrayList list = new ArrayList(); list.add("JavaFx"); list.add("Java"); list.add("WebGL"); list.add("OpenCV"); Collections.sort(list); System.out.println(list); Collections.reverse(list); System.out.println(list); } }Output:[Java, JavaFx, OpenCV, WebGL] [WebGL, OpenCV, JavaFx, Java]
Read MoreWhat is Java Method Area?
JVM has a method area common across all the threads. It contains per-class elements like constant pool, fields, method local data, method code, constructor codes etc. which are used in class and initialization of objects/interfaces.This method area gets created during JVM start-up. It is generally part of Heap area. It could be of fixed size or vary. Its memory may not be contiguous. JVM implementation can give control to programmer over Method area creation, its sizing etc. If method area memory is not sufficient to satisfy an allocation request then JVM throws OutOfMemoryError.
Read MoreWhat is Java Method Area?
JVM has a method area common across all the threads. It contains per-class elements like constant pool, fields, method local data, method code, constructor codes etc. which are used in class and initialization of objects/interfaces.This method area gets created during JVM start-up. It is generally part of Heap area. It could be of fixed size or vary. Its memory may not be contiguous. JVM implementation can give control to programmer over Method area creation, its sizing etc. If method area memory is not sufficient to satisfy an allocation request then JVM throws OutOfMemoryError.
Read MoreAtomic variables in Java
Yes, from Java 8 onwards, java.util.concurrent.atomic package contains classes which support atomic operations on single variables preventing race conditions or do not face synchronization issues. All classes in the atomic package have get/set methods. Each set method has a happens-before relationship with any subsequent get() method call on the same variable. import java.util.concurrent.atomic.AtomicInteger; class AtomicCounter { private AtomicInteger counter = new AtomicInteger(0); public void increment() { counter.incrementAndGet(); } public void decrement() { counter.decrementAndGet(); } public int value() { return counter.get(); } }
Read MoreAtomic variables in Java
Yes, from Java 8 onwards, java.util.concurrent.atomic package contains classes which support atomic operations on single variables preventing race conditions or do not face synchronization issues. All classes in the atomic package have get/set methods. Each set method has a happens-before relationship with any subsequent get() method call on the same variable. import java.util.concurrent.atomic.AtomicInteger; class AtomicCounter { private AtomicInteger counter = new AtomicInteger(0); public void increment() { counter.incrementAndGet(); } public void decrement() { counter.decrementAndGet(); } public int value() { return counter.get(); } }
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