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Merge Two list in Java in Efficient Way
While doing development many times we need to merge two or more collections in Java. Sometimes we need simple concatenate two or more lists or sets or merge two or more lists by removing duplicates and sometimes we need to do this is sorted order. Here is one example to merge two lists, this can…
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Best way to remove duplicate items from ArrayList in Java
Removing duplicate items from ArrayList in Java can be done in some very efficient ways using Java 8 or Guava lib for Java. Guava lib provides many efficient util classes to perform different operations on collections like creating, sorting, reversing, partitioning, etc. Removing duplicate using Guava API Here is the most efficient way to remove…
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Create, Partition and Reverse Array List Using Guava Lists
Guava Lists is part of the Guava core java library. It is used to perform many frequently used operations on an array lists like creation, partition, reversal, and many more. Java Guava lib is collection of very safe and handy libs for working with collection types (such as list, multimap, bimap, and multiset), immutable collections,…
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Quickest way to append text to a file in Java
In Java, there are several different ways to append text in a file. For file operations, Java provides several classes. To appending text quickly you can use Files class. Append text to file example: try { Files.write(Paths.get(“file1.txt”), “text to append”.getBytes(), StandardOpenOption.APPEND); } catch (IOException e) { // To exception handling here } But above method…
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How does Java for-each loop works?
Loops in programming languages used to iterate over collections like for loop, while .. do etc. In Java iterating over collections looks very ugly. Consider method in the following example which uses for loop to iterate over a collection. public static void main(String[] args) { List fruitList = new ArrayList(); fruitList.add(“mango”); fruitList.add(“banana”); fruitList.add(“apple”); printFruits(fruitList); }…
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Apache HttpClient with CookieStore (cookie support) in Java
In java many time we need to make a request with cookies support. For example, if a REST service is configured to manage session using cookie session or cookie-based session key then we need to use HTTP client with cookie support. For this Apache HttpClient client provides HttpClientBuilder Class, CookieStore interface and BasicCookieStore. Using these…
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Manually Closing connection of Apache HttpClient in Java
While Using Apache HttpClient library to make Http requests, we should always release connection immediately after completion of the operation. For making HttpRequest Apache HttpClient library provides CloseableHttpClient and CloseableHttpResponse classes which implements java closable interface. By calling the close method of a closeable object in finally block we can close or dispose of connection…
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Apache HttpClient Response Hadling in Java
Apache HttpClient library provides the ResponseHandler interface. By implementing ResponseHandler you can handle HTTP responses in a clean way. Using the response handler is the recommended way of executing HTTP requests and processing HTTP responses. This approach of handling response enables the caller to concentrate on the process of digesting HTTP responses and to delegate…
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Best way to round number to nth decimal place in Java
To format numbers, Java provides classes like NumberFormat and DecimalFormat classes. DecimalFormat is a concrete subclass of NumberFormat that formats decimal numbers. It has a variety of features designed to make it possible to parse and format numbers in any locale. All of these can be localized. Read more about DecimalFormat class on Oracle website.…
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What are ways to split the string in Java?
Java String class provides a method to split the string using a delimiter. It takes delimiter as a regular expression and Splits this string around matches of the given regular expression. This method has two overloaded versions. public String[] split(String regex, int limit) The array returned by this method contains each substring of this string that…