Banks mostly asked core Java interview questions from multi-threadingcollectionserialization, coding and OOPS design principles. Anybody who is preparing for any Java developer Interview on any Investment bank can be benefited from these set of core Java Interview questions and answers. I have collected these Java questions from my friends and I thought to share with you all.
Once you have absorbed the overview of how opencsv works, please consult the well-maintained Javadocs for further details.
Quick start This is limited to the easiest, most powerful way of using opencsv to allow you to hit the ground running. For reading, create a bean to harbor the information you want to read, annotate the bean fields with the opencsv annotations, then do this: What do you get for that?
Here is a list of the improvements in opencsv 4. We have rewritten the bean code to be multi-threaded so that reading from an input directly into beans is significantly faster.
We have rewritten the bean code to be multi-threaded so that writing from a list of beans is significantly faster. There is a new iterator available for iterating through the input into beans. This iterator is consistent in every way with the behavior of the code that reads all data sets at once into a list of beans.
The old iterator did not support all features, like locales and custom converters. The easiest way to benefit from this is to make certain the default locale is the one you want. Otherwise, look for the withErrorLocale and setErrorLocale methods in various classes.
Localizations are provided for American English and German. Further submissions are welcome, but with a submission you enter into a life-long contract to provide updates for any new messages for the language s you submit. If you break this contract, you forefit your soul.
Here are the things you can expect to encounter during an upgrade, and what to do about them. Java 7 is now the minimum supported version.
Everything that was deprecated has been removed. BeanToCsv is no more. Please use StatefulBeanToCsv instead. The quick start guide above gives you an example. It really is as simple as search and replace. In the rare case that you have written your own mapping strategy: MappingStrategy now includes a method verifyLineLength.
Otherwise, you will have to implement it. In the rare case that you used opencsv 3. They were the result of thought processes worthy of nothing more accomplished than a drunken monkey.
I may write that because I wrote the bad code. There are now requirements for thread-safety imposed on certain methods in every mapping strategy.
See the Javadoc for MappingStrategy for details. The method setErrorLocale is now required. If not, implement it, or make it a no-op. The method setType is now required. Null can be used for the default locale.
This is to avoid a proliferation of constructors or setters. These classes probably ought not to be used in your code directly, and probably ought to be final, but we still thought it best to inform you.
The interface BeanField requires the method setErrorLocale. Assuming you derive all of your BeanField implementations from AbstractBeanField, this does not affect you.
And we have a new list of things that we have deprecated and plan to remove in 5. CsvToBean itself is now iterable; use it instead. All constructors except the ones with the smallest often nullary, using defaults for all values and largest argument lists which often have only package access have been deprecated.
We encourage all of our users to use the builders we provide instead of the constructors. All variants of CsvToBean.Apache POI is a powerful Java library to work with different Microsoft Office file formats such as Excel, Power point, Visio, MS Word etc.
The name POI was originally an acronym for Poor Obfuscation Implementation, referring humorously to the fact that the file formats seemed to be deliberately obfuscated, but poorly, since they were successfully reverse-engineered.
That's all about how to read and write Excel file in Java. We have learned to read/write both XLS and XLSX format in Java, which is key to support old Microsoft Excel files created using Microsoft Office version prior to Though there are couple of other alternative libraries to read Excel files from Java program, but Apache POI is the best one and you should use it whenever possible.
Concise presentations of java programming practices, tasks, and conventions, amply illustrated with syntax highlighted code examples.
To write to a file, we'll use two more inbuilt classes: the FileWriter class and the PrintWriter class. Create a new class in your project by clicking File > New File from the NetBeans menu.
Select Java in the Categories section of the . Write to a file in which some contents are available already and you need to write the text at the end of line you may to use the FileWriter("String fileName", boolean append) this constructor creates a FileWriter object with the given file name with retaining the old text.
The Java FileWriter class (arteensevilla.comiter) makes it possible to write characters to a file. In that respect it works much like the FileOutputStream except that a FileOutputStream is byte based, whereas a FileWriter is character based. The FileWriter is intended to write text, in other words.
One character may correspond to one or more bytes, depending .