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♥ Reading a text file in Java with the Scanner

As a Java developer it is a very common task to read file contents to a String object. It is also very common in pre-interview written tests read the contents of a file and apply regex to split string, etc. 4 things to watch-out for in File processing 1) Files

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Posted in IO

♦ 15 Java old I/O and NIO (i.e. New I/O) interview Q&As

Q1. What is the purpose of Java I/O System? A1. The purpose is to provide an abstraction for all types of I/O like memory, file, directory, network, and pipe. Pipes in Java IO provides the ability for two threads running in the same JVM to communicate with each other. A…...

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Posted in IO, member-paid

♦ Processing large files efficiently in Java – part 1

Q1. What are the key considerations in processing large files? A1. Before jumping into coding, get the requirements. #1. Processing a file involves reading from the disk, processing (e.g. parsing an XML and transforming), and writing back to the disk. It is also a trade off in terms of what

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Posted in IO, Memory Management, Performance
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06: ♥ Java 8 way of File reading and functionally processing the data

Output: #1 double colon notation :: The new double colon (::) operator that Java 8 has to convert a normal method into lambda expression. So, Instead of: You can do: #2 Why is stream::iterator used? “lines::iterator” where iterator() is an instance method on “BaseStream<T,Stream<T>>” from which java.util.Stream<T> extends. The “iterator()”

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Posted in IO, Java 8
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Processing large files efficiently – BigData & Hadoop – part 3

Q1. What are the different data sizes, and what technologies can be used to process them? A1. In general, data sizes can be classified as shown below. 1) Small size data is < 10 GB in multiple files. It fits in a single machine’s memory when you process them by…...

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Posted in IO, member-paid, Performance

Processing large files efficiently in Java – multi-threaded code – part 2

If you want to process medium sized data (e.g. 2 GB to 1 TB in multiple files) in Java, consider writing a batch job with Spring batch or Java EE 7.0 batch processing. If processing requires access to other systems, use “spring integration” with spring batch. This is also known…...

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Posted in IO, member-paid, Performance

Read a text file from Java classpath

File to read: src/main/resources/examples/request.xml 1. Using Java API without any libraries You can also use the “ClassLoader” 2. Using Java 7 NIO 3. Using Apache commons-io library 4. Using Spring library 5. Using Java 8 API

Posted in IO

Reloading configuration files in Java without stopping the server

Q1. Why & when do you want to use properties files for the project configuration as opposed to Java constants? A1. It is a best practice to externalize application related properties that are likely to change. If you hard code the properties that are likely to change, then you need

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Posted in IO

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