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This is one of the many interesting multi-threading questions I have shared in my post 50 multi-threading interview questions . Yes, you can make an array volatile in Java, there is no problem with that, neither compiler will flag any error not JVM will throw any exception but the tricky part is why you want to make an array volatile and what is the effect of making an array volatile in Java? In order to answer this question you must be familiar with both volatile modifier and Java memory model , otherwise, it would be difficult to answer, and that's why it's also one of the trick questions from Java interviews. Before answering this question in detail, let's first revise what is a volatile keyword in Java and what kind of guarantee it provides in the context of multithreading and concurrency. Read more �

This Java tips is about, how to reverse array in Java, mostly primitive types e.g. int , long , double and String arrays. Despite of Java�s rich Collection API, use of array is quite common, but standard JDK doesn�t has great utility classes for Java. It�s difficult to convert between Java Collection e.g. List , Set to primitive arrays. Java�s array utility class java.util.Arrays , though offers some of critical functionalities like comparing arrays in Java and support to print arrays , It lacks lot of common features, such as combining two arrays and reverse primitive or object array. Thankfully, Apache commons lang, an open source library from Apache software foundation offers one interesting class ArrayUtils, which can be used in conjunction with java.util.Arrays class to play with both primitive and object array in Java. This API offers convenient overloaded method to reverse different kinds of array in Java e.g. int, double, float, log or Object arrays. On a similar note,...

There are multiple ways to generate the MD5 hash in Java program. Not only Java API provides a convenient method for generating MD5 hash, you can also use popular open source frameworks like Spring and Apache commons Codec to generate MD5 digest in Java. MD5 is popular Message Digest Algorithm, which is most commonly used to check data integrity e.g. comparing MD5 checksum to see, if any file is altered or not. Though MD5 has not considered a good cryptographic algorithm for security purpose due to several vulnerabilities found on it, it's still good enough or checking the integrity of the file. MD5 hashing algorithm generates a 128 bit or 16-byte long hash value. MD5 hash values , also known as MD5 digest is mostly represented as 32 character Hex String. You can generate an MD5 hash from a byte array , or String directly using Java, Spring and Apache commons codec. Spring and Apache commons codec has identical API e.g. class name DigestUtil s is same and allows you to directl...

There are multiple ways to combine or join two arrays in Java, both for primitive like int array and Object e.g. String array. You can even write your own combine() method which can use System.arrayCopy() to copy both those array into the third array. But being a Java developer, I first looked in JDK to find any method which concatenates two arrays in Java. I looked at java.util.Arrays class, which I have used earlier to compare two arrays and print arrays in Java , but didn't find a direct way to combine two arrays. Then I looked into Apache Commons, ArrayUtils class, and bingo, it has several overloaded method to combine int , long , float , double or any Object array. Later I also found that Guava ,earlier known as Google collections also has a class ObjectArrays in com.google.common.collect the package, which can concatenate two arrays in Java. It's always good to add Apache commons and Guava , as supporting library in Java project, they have lots of supporting clas...

java.util.Arrays class provides equals() and deepEquals() method to compare two Arrays in Java. Both of these are overloaded method to compare primitive arrays e.g. int, long, float, double and Object arrays e.g. Arrays.equals(Object[] , Object[]). Arrays.equals() returns true if both Arrays which it is comparing are null If both arrays pointing to same Array Object or they must be of the same length and contains the same element in each index. In all other cases, it returns false. Arrays.equals() calls equals() method of each Object while comparing Object arrays. One of the tricky question in Java related to Array comparison is Difference between Arrays.equals() and Arrays.deepEquals() method. Since both equals and deepEquals is used for array comparison, what is the difference between them becomes important. The short answer of this questions is that, Array's equals() method does not perform deep comparison and fails logical comparison in case of nested Array, on o...

Printing array values in Java or values of array element in Java would have been much easier if arrays are allowed to directly prints its values whenever used inside System.out.println() or format and printf method , Similar to various classes in Java do this by overriding toString() method . Despite being an object, array in Java doesn't print any meaningful representation of its content when passed to System.out.println() or any other print methods. If you are using array in method argument or any other prominent place in code and actually interested in values of array then you don't have much choice than for loop until Java 1.4. Things has been changed since Java 5 because it introduced two extremely convenient methods for printing values of both primitive and object arrays in Java . Arrays.toString(array) and Arrays.deepToString(twoDimensionArray) can print values of any array. Main difference between Arrays.toString() and Arrays.deepToString is that deepToString i...

Searching in Java Array sounds familiar? should be, because its one of frequently used operations in Java programming. Array is an index based data structure which is used to store elements but unlike Collection classes like ArrayList or HashSet which has contains() method, array in Java doesn't have any method to check whether an element is inside array or not. Java programming language provides several ways to search any element in Java array . In this Java tutorial we will see 4 examples of searching Array in Java for an element or object. Every example is different than other and some of them are faster and others are slow but take less memory. These technique also valid for different types of array e.g. primitive and object array. I always suggest to prefer List over Array until you need every bit of performance from your Java application, it not only convenient to work but also more extensible. Read more �