Java

URL: https://www.progressiverobot.com/java-futuretask-example-program/ Sometime back I wrote a post about [Java Callable Future](/community/tutorials/java-callable-future-example) interfaces that we can use to get the concurrent processing benefits of threads as well as they are capable of returning value to the calling program. FutureTask is base concrete implementation of Future interface and provides asynchronous processing. It contains the methods to […]

URL: https://www.progressiverobot.com/java-lang-nullpointerexception/ java.lang.NullPointerException is one of the most popular [exceptions in java](/community/tutorials/exception-handling-in-java) programming. Anybody working in java must have seen this popping out of nowhere in the java standalone program as well as the [java web application](/community/tutorials/java-web-application-tutorial-for-beginners). java.lang.NullPointerException NullPointerException is a runtime exception, so we don’t need to catch it in the program. NullPointerException is raised in an […]

URL: https://www.progressiverobot.com/java-randomaccessfile-example/ Java RandomAccessFile provides the facility to read and write data to a file. RandomAccessFile works with file as large [array of bytes](/community/tutorials/string-byte-array-java) stored in the file system and a cursor using which we can move the file pointer position. Java RandomAccessFile !Java RandomAccessFile, RandomAccessFile in java, Java RandomAccessFile read write append example RandomAccessFile […]

URL: https://www.progressiverobot.com/java-sort-list/ Sometimes we have to sort a list in Java before processing its elements. In this tutorial, we will learn how to sort a list in the natural order. We will also learn how to use our own Comparator implementation to sort a list of objects. Java List is similar to arrays except that […]

URL: https://www.progressiverobot.com/java-thread-join-example/ Java Thread join method can be used to pause the current thread execution until unless the specified thread is dead. There are three overloaded join functions. Java Thread join  public final void join(): This java thread join method puts the current […]

URL: https://www.progressiverobot.com/pyramid-pattern-programs-in-java/ Pattern programs are used a lot in interviews to understand the logical thinking abilities of the interviewee. Pyramid patterns are very popular and once we get the logic on the way it's created, writing code to achieve the same is an easy task. Pyramid Pattern Programs in Java !Pyramid Pattern Programs in Java […]

URL: https://www.progressiverobot.com/sort-hashmap-by-value-java/ HashMap in java provides quick lookups. They store items in "key, value" pairs. To get a value from the HashMap, we use the key corresponding to that entry. HashMaps are a good method for implementing Dictionaries and directories. Key and Value can be of different types (eg – String, Integer). We can sort […]