Article Categories
- All Categories
-
Data Structure
-
Networking
-
RDBMS
-
Operating System
-
Java
-
MS Excel
-
iOS
-
HTML
-
CSS
-
Android
-
Python
-
C Programming
-
C++
-
C#
-
MongoDB
-
MySQL
-
Javascript
-
PHP
-
Economics & Finance
Articles by raja
Page 38 of 38
Why the java file name should be always the same as a public class name?
In Java, the java file name should be always the same as a public class name.While writing a java program first it is saved as a ".java" file, when it is compiled it forms byte code which is a ".class" file as such that if we made our program file similar to the class it will be comfortable for us to understand without any ambiguity. We are allowed to use any name for a filename only when class is not public. In the case of a public class, we can’t use a different file name.The filename ...
Read MoreCan we access the instance variables from a static method in Java?
We cannot directly access the instance variables within a static method because a static method can only access static variables or static methods.An instance variable, as the name suggests is tied to an instance of a class. Therefore, accessing it directly from a static method, which is not tied to any specific instance doesn't make sense. Therefore, to access an instance variable, we must have an instance of the class from which we access the instance variable.Example:public class Test { public int instanceVariable = 10; public static void main(String args[]) { Test test ...
Read MoreCan an interface extend multiple interfaces in Java?
Yes, we can do it. An interface can extend multiple interfaces in Java.Example:interface A { public void test(); public void test1(); } interface B { public void test(); public void test2(); } interface C extends A,B { public void test3(); } class D implements C { public void test() { System.out.println("Testing"); } public void test1() { System.out.println("Testing1"); } public void test2() { System.out.println("Testing2"); } public void test3() { System.out.println("Testing3"); } } public class Main { public static void main(String[] args) { D d=new D(); d.test(); d.test1(); d.test2(); d.test3(); } }Output:Testing Testing1 Testing2 Testing3
Read MoreWhat is Double-buffering in Java?
Double-buffering is the process of drawing graphics into an off-screen image buffer and then copying the contents of the buffer to the screen all at once.For the complex graphics, using double-buffering can reduce flickering issues.Java Swing automatically supports double-buffering for all of its components.Double-buffering is memory intensive, its use is only justified for components that are repainted very frequently or have particularly complex graphics to display.If a container uses double-buffering, any double-buffered children it has shared the off-screen buffer of the container, the required off-screen buffer is never larger than the on-screen size of the application.To enable double buffering, simply ...
Read MoreHow to make a class thread-safe in Java?
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 HashMap is a non-synchronized collection class. If we need to perform thread-safe operations on it then we must need to synchronize it explicitly.Example:import java.util.Collections; import java.util.HashMap; import java.util.Map; import java.util.Set; import java.util.Iterator; public class HashMapSyncExample { public static void main(String args[]) { HashMap hmap = new HashMap(); hmap.put(2, "Raja"); hmap.put(44, "Archana"); hmap.put(1, "Krishna"); ...
Read MoreHow to understand StringBuffer is thread-safe and StringBuilder is non-thread-safe in Java?
StringBuffer(Thread-safe)StringBuffer is thread-safe meaning that they have synchronized methods to control access so that only one thread can access StringBuffer object's synchronized code at a time.StringBuffer objects are generally safe to use in a multi-threaded environment where multiple threads may be trying to access the same StringBuffer object at the same time.StringBuilder(Non-thread-safe)StringBuilder is not synchronized so that it is not thread-safe. By not being synchronized, the performance of StringBuilder can be better than StringBuffer.If we are working in a single-threaded environment, using StringBuilder instead of StringBuffer may result in increased performance. This is also true of other situations such as ...
Read MoreHow to resize an array in Java?
An array cannot be resized dynamically in Java. One approach is to use java.util.ArrayList(or java.util.Vector) instead of a native array.Another approach is to re-allocate an array with a different size and copy the contents of the old array to the new array.Example:class ResizableArray { public static void main (String[] args) { int[] a = {1, 2, 3}; a = (int[])resizeArray(a, 5); a[3] = 4; a[4] = 5; for (int i=0; i 0) System.arraycopy(oldArray, 0, newArray, 0, preserveLength); return newArray; } } Output:1 2 3 4 5
Read MoreMust we implement all the methods in a class that implements an interface in Java?
Yes, it is mandatory to implement all the methods in a class that implements an interface until and unless that class is declared as an abstract class.There are only two choices −Implement every method defined by the interface.Declare the class as an abstract class, as a result, forces you to subclass the class (and implement the missing methods) before you can create any objects.The only case the class do not need to implement all methods in the interface is when any class in its inheritance tree has already provided concrete (i.e. non-abstract) method implementations then the subclass is under no ...
Read MoreHow to set JAVA_HOME environment variables on Windows OS in Java?
Once you have installed JDK version on your windows machine, you have to set up Environment Variables.Please find below steps to set the java pathGo to My Computer ---> Right Click on it ---> Advanced System Settings ---> Advanced Tab ---> Click on Environment VariablesNow you have to alter the “Path” variable under system variables such that it contains a path to Java Environment. Select the path variable and click on the “Edit” buttonBy default, Java is installed in “C:\Program Files\Java\jre version\bin” in case you have changed the location of installation, then add that pathClick on OK button and now ...
Read More