There are two types of polymorphism:
1) Compile Time Polymorphism (Method Overloading) – Here it is clear at compile time that which method call in the program will invoke which of the methods.
2) Runtime Polymorphism (Method Overriding) – Here it is determined at run time that which method needs to be Read more…
How Java achieves platform independence
First thing is what platform independence means?
It means compiled Java code can run on any OS without change.
Now the question is how Java achieves this?
Java achieves this with the help of Bytecode and JVM (which is OS dependent).
When we compile a Read more…
SerialVersionUID is a class invariant that is used to validate that the classes on both sides of the wire are the same. During Serialization it marshals an object and sends it over the stream. During marshalling process, the SerialVersionUID is also transferred over the wire. The receiving process (Deserialization) compares Read more…
AWS Amazon CloudFront is a web service that speeds up serving static and dynamic web content like, .html, .css, .php, and image files and videos. It also integrates with other Amazon Web Services like S3, EC2, Elastic Load Balancer and Route 53. It also works seamlessly with any non-AWS Read more…
Default method, a new concept used for interfaces has been added to Java 8.
Purpose: In Java 7 or older, classes implementing an interface were forced to implement each method of the interface. Consider a long running project in which an interface is implemented by several classes and Read more…
Java does not support call by reference because in call by reference we need to pass the address and address are stored in pointers. Java does not support pointers and it is because pointers break the security. Java does manipulate objects by reference and all object variables are references. Pass Read more…
In this post I will give an example of how to upload a csv file with Selenium script to a webpage. Below is the screenshot of webpage:
Code to automatically select a csv file and then click Submit button is given below. Go through the comments in the code.
package Read more…
Slanted text and Images in CSS for different browser is given by transform property in CSS. We need to specify the angle by which to slant the image or text. Angle can be negative or positive. Positive angle inclines the image in clockwise direction and negative angle inclined it in Read more…
Problem: Trap incoming email and extract email content with attachments in Salesforce
Solution: Salesforce provides us a mechanism to trap incoming emails on a specific email id and extra email contents including attachments out of it. To achieve this we need to follow these steps:
Problem: How to insert csv data into mysql table with mysql query in php. What problems usually you face with this and how to resolve them.
Description: I have csv file with thousands of records. I want to insert these records in mysql table with php Read more…
Introduction: In Moodle/Totara we can add a different type of activities to a course by selecting from the list of standard activities available. As shown in the the list below:
But there might be some cases in which we need to add a custom activity to a Read more…
We can move elements on background screen using CSS properties.
Below @keyframes rule specifies the animation code and “movement” gives a name to the animation:
@keyframes movement {
0 % {
background – position: 0 px 0 px,
0 px 0 px,
0 px 0 px
}
50 % {
background – color: #FFA07A
}
100 % {
background – position: 500 Read more…
Question: What is the difference between return, continue, break and System.exit statements in Java?
Answer: The differences among these 4 statements are described here Read more…
During testing, I had a test case to add multiple employees automatically with selenium script so I have implemented Data Driven Framework. Using this we have to read the data from the CSV and register all the users in the system.
Note: We need to add a jar Read more…
When you do svn update or commit in Eclipse you may face this problem- “working copy xxxxx locked”
Solution: Sometimes the problem can be solved with “project cleanup” or “move the project to some other location without .project and .svn files”. But you may have to solve it Read more…
What is Enum/Enumeration?
Enum/Enumeration is a data type in Java which is used to store a fixed set of constant values. For example, number of days in a week or a set of arithmetic operators (addition, subtraction, multiplication and division) or status of a customer’s bank account Read more…
Suppose you have a class like this:
public class Student {
private String name;
private int rollNumber;
private int grade;
private List subjects;
}
This is the Subject class
public class Subject {
private String sName;
}
You have an object sObj1 of Student class and it also contains a list of subjects assigned Read more…
We can create and run the java Mapreduce programs in Eclipse as well as from command line.
Using Eclipse – For Eclipse first we have to install the plugin for hadoop mapreduce which inherits the libraries required to implement the mapreduce functionality. After this we have to build the path which Read more…
Static Blocks: Static block is used to initialize the static data members. It is executed before main method and constructor at the time of classloading. A class can have any number of static initialization blocks and they can appear anywhere in the class body. The runtime system guarantees Read more…
Interface:
In Java we have a concept called interfaces.A Java interface is same like a class, except a Java interface cannot contain an implementation of the methods, we have only signature of the method.It has static constants data member.
Can interfaces contain variables?
Yes, Interface can contain only Read more…
