Category: Java

  • 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…

  • 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…

  • 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.…

  • 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…

  • Best way to generate random integers within a specific range in Java

    There are many classes in Java to generate random numbers. Random and ThreadLocalRandom are best to generate numbers between ranges. ThreadLocalRandom class Since Java 7, it provides ThreadLocalRandom class to generate random numbers. A random number generator isolated to the current thread. Like the global Random generator used by the Math class, a ThreadLocalRandom is…

  • Best and Simplest ways to print Java Array

    Many time printing arrays in Java are required to logging and debugging purpose. In Java provides Arrays.toString(arr) or Arrays.deepToString(arr) for arrays within arrays (a nested array) to formatting simple arrays into printable strings. Example of printing a simple array: String names[] = new String[] {“ssp”,”anu”,”kirti”,”shaurya”}; System.out.println(names); System.out.println(Arrays.toString(names)); the output of above code is given below: [Ljava.lang.String;@2a139a55 [ssp, anu,…

  • Best way to prevent ArrayIndexOutOfBoundsException in Java

    ArrayIndexOutOfBoundsException is an exception, thrown to indicate that an array has been accessed with an illegal index. The index is either negative or greater than or equal to the size of the array. illegal index in java is index value less than zero or -ve values and index value equal to or greater than array…

  • Is Java method parameters are “pass-by-reference” or “pass-by-value”?

    Is Java method parameters are “pass-by-reference” or “pass-by-value”?

    Many beginners think that Java is pass-by-reference. The Java specification document says that everything in Java is pass-by-value. There is no such thing as “pass-by-reference” in Java and this is fact. In Java when we pass an object to some method parameter it actually passes objects reference value which many people think that it is…

  • Best way to compare strings in Java

    In Java, strings are the reference type. So we can not compare two strings using the == operator as it compares references (will only return true when both references are of the same object). In Java, all objects are derived from class Object which has one method equals, which is used to compare equality of…

  • What is NullPointerException in Java, and how to avoid and fix it?

    In Java NullPointerExceptions are exceptions that occur when we try to use a reference that points to no location in memory (Know as null) as though it were referencing an object (uninitialized objects or assigned to null object references). Calling a method or accessing a member on a null reference will throw a NullPointerException. Generally,…