Comparator and Comparable are two interfaces in Java API, which is used to compare two objects in Java. Though both are used for comparison there are some differences between them, a major difference between Comparable and Comparator is that the former is used to define the natural ordering of objects e.g. lexicographic order for java.lang.String, while later is used to define any alternative ordering for an object. The main usage of java.lang.Comparable and java.util.Comparator interface is for sorting a list of objects in Java.
How to Iterate over Java Enum : values() Example
Enum Values() Example
In this Java programming tutorial, we will learn how to iterate over enum in Java. Since Enums are a collection of a finite number of well-known objects, often we need to iterate over them. Enums are also final in Java and have a private constructor, which means you can not create enum instances once declared. Iteration over Enum is extremely simple, provided you know about the implicit values() method, which is a static method, provided by java.lang.Enum. Since every enum in Java extends java.lang.Enum, they all get this implicit values() method. Actually there are couple of them, e.g. valueOf(), name(), ordinal() etc. This method returns enum constants in the order they are declared in the Enum class. Even the ordinal() method returns the same order.
In this Java programming tutorial, we will learn how to iterate over enum in Java. Since Enums are a collection of a finite number of well-known objects, often we need to iterate over them. Enums are also final in Java and have a private constructor, which means you can not create enum instances once declared. Iteration over Enum is extremely simple, provided you know about the implicit values() method, which is a static method, provided by java.lang.Enum. Since every enum in Java extends java.lang.Enum, they all get this implicit values() method. Actually there are couple of them, e.g. valueOf(), name(), ordinal() etc. This method returns enum constants in the order they are declared in the Enum class. Even the ordinal() method returns the same order.
How to Split String in Java using Regular Expression
String class provides split() method to split String in Java, based upon any delimiter, e.g. comma, colon, space or any arbitrary method. split() method splits the string based on delimiter provided, and return a String array, which contains individual Strings. Actually, split() method takes a regular expression, which in simplest case can be a single word. split() is also overloaded method in java.lang.String class and its overloaded version take a limit parameter which is used to control how many times the pattern will be applied during the splitting process. if this limit is positive n, then the pattern will be applied at most n-1 times, if it's negative or zero then split operation is applied any number of times.
Difference between Deep and Shallow Copy in Java Object Cloning
Shallow copy and deep copy is related with cloning process so before go into the deep of shallow and deep copy we need to understand what is clone in java. Clone is nothing but the process of copying one object to produce the exact object, which is not guaranteed. We all know in Java object is referred by reference we can not copy one object directly to another object. So we have a cloning process to achieve this objective. Now one question arises in mind why we need this process so the answer is whenever we need a local copy of the object to modify the object in some method but not in the method caller.
How to Create File and Directory in Java with Example
Many beginners confused with the fact that the same class java.io.File is used to create both file and directories in Java. I agree, this is not very intuitive and junior developers probably start looking for a class called java.io.Directory, which doesn't exist. On the other hand, creating file and directories are simple in Java, as java.io.File provides methods like createNewFile() and mkdir() to create new file and directory in Java. These methods returns boolean, which is the result of that operation i.e. createNewFile() returns true if it successfully created file and mkdir() returns true if the directory is created successfully.
When to use ArrayList vs LinkedList in Java? [Answered]
Java Regular Expression to Check If String contains at least One Digit
This week's task is to write a regular expression in Java to check if a String contains any digit or not. For example, passing "abcd" to pattern should false, while passing "abcd1" to return true, because it contains at least one digit. Similarly passing "1234" should return true because it contains more than one digit. Though java.lang.String class provides a couple of methods with inbuilt support of regular expression like split method, replaceAll(), and matches method, which can be used for this purpose, but they have a drawback. They create a new regular expression pattern object, every time you call. Since most of the time we can just reuse the pattern, we don't need to spend time on creating and compiling patterns, which is expensive compared to testing a String against the pattern.
How to Convert java.util.Date to java.sql.Date - Example
Hello guys, you may not know but there are two date classes in Java, one in java.util package and other in the java.sql package. Though both are known as Date class, there is some difference between java.util.Date and java.sql.Date e.g. Former is used whenever a Date is required in Java application while later is used to read and store DATE SQL type from the database. There is one more important difference is, java.util.Date stores both date and time values, while java.sql.date only stores date information, without any time part. As per Javadoc, java.sql.date is a thin wrapper around a millisecond value that allows JDBC to identify this as an SQL DATE value. To conform with the definition of SQL DATE, the millisecond values wrapped by a java.sql.Date instance must be 'normalized' by setting the hours, minutes, seconds, and milliseconds to zero in the particular time zone with which the instance is associated. See SQL date vs Util date for few more differences.
How to find largest and smallest number from integer array - Java Solution
Hello guys, if you have gone through any coding interview or have done some professional Software development then you know that a good understanding of array data structure is crucial for any software developer but it doesn't come for free, you need to spend time and effort. The best way to develop this understanding by solving coding problems and there are lots of programming exercises beginners can do. One of them is writing a program to find the smallest and largest number in an integer array. Java programmers are no different than others, so they can do this program in Java, not just to understand array but also different relational operators available in Java.
Difference between GET and POST Request in HTTP and REST APIs
HTTP Protocol supports many methods to retrieve data from the server or perform any operation on the server, like upload data, delete the file, etc. In total, the HTTP protocol supports the following methods, GET, POST, PUT, DELETE, HEAD, DELETE, OPTIONS, and TRACE, and the HTTP 1.1 reserves technique called CONNECT for future use. GET, and POST is two of the most common HTTP methods you would hear or work on the web. Though both can be used to send and receive data from client to server, there are some crucial differences between the GET and POST in HTTP, which will help you to understand when you should use GET vs. POST while writing your client and server application.
How to Prepare for Java Certifications like OCAJP, OCPJP, or Java SE 11 Developer?
There is No doubt that Oracle's Java certification is one of the most valuable certifications for the IT industry and helps you to get a better job, better pay, and a better rise in your current salary. It also improves your recognition and job prospects because many big clients demands certified Java programmers for their mission-critical applications. Because of enormous popularity and usefulness, many Java developers and computer science graduates aspire for Java certifications. I often receive queries like, what is the best way to prepare for Java certifications like OCAJP or OCPJP?
java.lang.UnsatisfiedLinkError: Library not found tibrvnative or android
When I was working in JNI and using native code, actually an in-house library, I realized that java.lang.UnsatisfiedLinkError: Library not found comes mainly due to two reasons
1) First reason, which happens in 90% of scenarios is that the library which you are using directly or indirectly (some external JAR is using native library or native dll e.g. if your Java application is using TIBCO libraries for messaging or fault tolerance then tibrv.jar uses tibrvnative.dll library and throws java.lang.UnsatisfiedLinkError: Library not found tibrvnative if that library (the dll) is not in the path. In order to fix this problem, you need to update your PATH environment variable to include native libraries binary. see last section for more details.
1) First reason, which happens in 90% of scenarios is that the library which you are using directly or indirectly (some external JAR is using native library or native dll e.g. if your Java application is using TIBCO libraries for messaging or fault tolerance then tibrv.jar uses tibrvnative.dll library and throws java.lang.UnsatisfiedLinkError: Library not found tibrvnative if that library (the dll) is not in the path. In order to fix this problem, you need to update your PATH environment variable to include native libraries binary. see last section for more details.
Can Abstract class have Constructor in Java? Interview Question
Yes, an abstract class can have a constructor in Java. You can either explicitly provide a constructor to the abstract class or if you don't, the compiler will add a default constructor of no argument in the abstract class. This is true for all classes and it also applies to an abstract class. For those who want to recall what is an abstract class in Java, it's a class that can not be instantiated with the new() operator or any other way. In order to use an abstract class in Java, You need to extend it and provide a concrete class. An abstract class is commonly used to define a base class for a type hierarchy with default implementation, which is applicable to all child classes.
How to use Iterator Java - Example Tutorial
The Iterator is used to iterate over all elements of a Collections in Java. By Iteration, I mean, going over each element stored in the collection and optionally performing some operation like printing value of an element, updating object or removing an object from Collection. Iterator was not part of the first Java release, and a similar class Enumeration was there to provide Iteration functionality. Iterator in Java was introduced from JDK 1.4 and it provides an alternative to Enumeration, which is obsolete nowadays. An iterator is different from Enumeration in two main ways, first, Iterator allows a programmer to remove elements from Collection during iteration.
Java 8 Optional isPresent(), OrElse() and get() Examples
The Optional class in Java is one of many goodies we have got from the Java 8 release. If you use it correctly, Optional can result in clean code and can also help you to avoid NullPointerException which has bothered Java developers from its inception. Even though many of us have used null to indicate the absence of something, the big problem is that if you call a method or access a field on the null object (except static fields), you will get a NullPointerException and your whole program may crash.
Polymorphism, Overloading, and Overriding in Java and Object Oriented Programming?
Polymorphism vs Overloading vs Overriding
Someone asked me the other day, what are the difference between Polymorphism and Overriding in Java and the similar difference between Polymorphism and Overloading. After explaining to him personally, I thought to write a blog post about it and here we are. Well, they are not two different things, Polymorphism is an object-oriented or OOP concept much like Abstraction, Encapsulation, or Inheritance which facilitates the use of the interface and allows Java program to take advantage of dynamic binding in Java. Polymorphism adds flexibility to your code which makes it more extensible and maintainable.
Default Methods and Multiple Inheritance in Java 8
Ever since Java 8 introduced default and static methods in JDK 8, it's become possible to define non-abstract methods in interfaces. Since Java, one class can implement multiple interfaces and because there can be concrete methods in interfaces, the diamond problem has surfaced again. What will happen if two interfaces have methods o the same name and a Java class inherit from it? Many Java programmer also asks me the question that, is Java 8 is also supporting multiple inheritances of classes? Well, it's not but the doubt is genuine because the interface with methods is similar to an abstract class or in that any Class in Java.
10 Examples of Collectors + Stream in Java 8 - groupingBy(), toList(), toMap()
As the name suggests, the Collectors class is used to collect elements of a Stream into Collection. It acts as a bridge between Stream and Collection, and you can use it to convert a Stream into different types of collections like List, Set, Map in Java using Collectors' toList(), toSet(), and toMap() method. Btw, Collector is not just limited to collection stream pipeline results into various collection class, it even provides functionalities to join String, group by, partition by, and several other reduction operators to return a meaningful result. It's often used along with the collect() method of Stream class which accepts Collectors. In this article, you will learn how to effectively use java.util.stream.Collectors in Java by following some hands-on examples.
How to use Spliterator in Java 8 - Example Tutorial
Hello friends, we are here today again on the journey of Java. And today, we are gonna learn about SplitIterator class from Stream package that may not be used in your day-to-day life but can be very useful to know as Java internally does use this with both normal streams and parallel streams. As always, let’s take an example of a situation. I will present you with a situation and you guys can think about it. So, let’s say we have an array with 50k records in it. Now, these all records need to be modified, let’s say they are strings and we need to append the string with a name. Now, traversing the array sequentially would be time-consuming. Any innovative ideas my friends?
Difference between Docker Kubernetes for Programmers and DevOps
Hello guys, If you're a Java developer or doing Software Development in any programing language and interested in cloud-based technologies like containers, you've probably heard of Docker and Kubernetes and may be wondering what they are and how they connect. Should I use Kubernetes or Docker? is a common way to start the debate between the two. Earlier, I have explained you why Every programmer should learn Docker and Kubernetes and In this article, we are going to discuss these two technologies again and see the difference between Docker and Kubernetes and find out how they differ from each other, when to use Docker and Kubernetes, and what value they provide.
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