Programming Corner

If you have not read my article on Java records and do not know about this topic, please read my blog titled " Customizing Java Records " first and then come back to this one. Now that you know how to customize Java records, implementing an interface using Java records should be very easy to understand. If you don't know about interfaces in Java, you can read more on my article about interfaces. The recipe for implementing an interface is simply an expansion of what you learned in my previous blog on how to customize a Java record. Following our Rectangle example, let's create an interface with the same two methods we used before. public interface Shape { double area(); double perimeter(); } Now, let's further customize the previous example by doing two things: Add implements Shape at the end of the record declaration (after the record constructor), and Add @Override to the existing methods to ensure these methods com...

If you have not read my article on Java records and do not know about this topic, please read my blog titled " Java Keywords Addendum: The Java Record " first and then come back to this one. What is a customization of a record? A customization of a record is simply the addition of code inside the body of the class. Before proceeding further, let's recap important aspects of a Java Record: Java records are immutable Because of item 1 above, you cannot add new fields unless defined in the record constructor Java records already override: Object#equals(Object) and Object#hashCode() , and then override Object#toString() You could redefine overridden methods as part of your customization if you would like. For example, if you want a fancier implementation of the Object#toString() method, you could do so. Let's look at our first customization example. Using the example from my previous blog, public record Student(...

Since originally my Java series was based on Java 8, it did not include a new keyword introduced later on. For that reason, I decided to post an addition to the Java Keyword series to include the Java record keyword. Introduced in Java 14, the purpose of this keyword is to eliminate all the boilerplate code when creating a Java POJO. For example, public class Student { private String name; private int id; public Student(String name, int id) { this.name = name; this.id = id; } public String getName() { return name; } public int getId() { return id; } public void setName(String name) { this.name = name; } public void setId(int id) { this.id = id; } } can be replaced simply with a record that looks like this: public record Student(String name, int id){ } And not only it replaces the boilerplate code I showed you, it also automatically overrides Object#equals(Object) , Object#hashCode() , and Object#toStr...

Java keyword list abstract continue for new switch assert default goto * package synchronized boolean do if private this break double implements protected throw byte else import public throws case enum instanceof return transient catch extends int short try char final interface static void class finally long strictfp volatile const * float native super while Keyword marked with an asterisk (*) are keywords that, although valid, are not used by programmers. This is going to be an easy one. As of Java 17, this keyword is obsolete. Prior to Java 17, this keyword was used to establish a strict floating-point (strict fp) policy. This meant that, when in use, this keyword guaranteed that floating point calculations would yield the same result across all hardware. When not in use, the Operating System had some leeway in refining precision of floating-point calculations. The keyword would be applied at ...

Java keyword list abstract continue for new switch assert default goto * package synchronized boolean do if private this break double implements protected throw byte else import public throws case enum instanceof return transient catch extends int short try char final interface static void class finally long strictfp volatile const * float native super while Keyword marked with an asterisk (*) are keywords that, although valid, are not used by programmers. The assert keyword enables you to test an assumption about a part of your program. If the assertion is proven to be true, execution of your program will continue. If it's proven to be false, an AssertionError will be thrown. Assertions confirm your assumptions about the behavior of your program, thus increasing confidence that the program is free of errors. This keyword has been part of the Java language since Java 1.4.2 and yet, very l...

This article summarize the use of the keyword static . I suggest you review Java Keywords (Part V): Classes vs Interfaces and Java Keywords (Part IX): Switch Statements before proceeding. Java keyword list abstract continue for new switch assert default goto * package synchronized boolean do if private this break double implements protected throw byte else import public throws case enum instanceof return transient catch extends int short try char final interface static void class finally long strictfp volatile const * float native super while Keyword marked with an asterisk (*) are keywords that, although valid, are not used by programmers. Very early in this series, I discussed the use of the keyword static and mentioned that I would leave for later discussion another use of that keyword. Well, the time has come. Using static method in interfaces Let me start by saying that the only re...

This article summarize the use of the keyword default . I suggest you review Java Keywords (Part V): Classes vs Interfaces and Java Keywords (Part IX): Switch Statements before proceeding. Java keyword list abstract continue for new switch assert default goto * package synchronized boolean do if private this break double implements protected throw byte else import public throws case enum instanceof return transient catch extends int short try char final interface static void class finally long strictfp volatile const * float native super while Keyword marked with an asterisk (*) are keywords that, although valid, are not used by programmers. Up until Java 8 (released in March, 2014), the default keyword had a single purpose, which was to indicate the default case in a switch statement. To illustrate quickly String color = "red"; switch(color) { case "red": case ...

We are up to 40 keywords covered in previous articles! That's 83% keywords covered. We have only 8 keywords to cover and I will be covering 1 of those in this article. We are almost done with all the basic keywords. This article will illustrate the use of the keyword super . I suggest you start with Java Keywords (Part I) before proceeding further, if you have not read any of the previous articles in the Java Keyword series. Also, go back and read the one about Data Types. All of these articles are from September 2018. That should help you find them quickly. You can also use the "search" option at the top of this page. The series was written with natural progression in mind. Therefore, some of the keywords already covered may be used in code examples illustrated here. Java keyword list abstract continue for new switch assert default goto * package synchronized boolean do if private this break double implements protected throw ...

We are up to 39 keywords covered in previous articles! That's 81% keywords covered. We have only 9 keywords to cover and I will be covering 1 of those in this article. We are almost done with all the basic keywords. This article will illustrate the use of the keyword this . I suggest you start with Java Keywords (Part I) before proceeding further, if you have not read any of the previous articles in the Java Keyword series. Also, go back and read the one about Data Types. All of these articles are from September 2018. That should help you find them quickly. You can also use the "search" option at the top of this page. The series was written with natural progression in mind. Therefore, some of the keywords already covered may be used in code examples illustrated here. Java keyword list abstract continue for new switch assert default goto * package synchronized boolean do if private this break double implements protected throw ...

We are up to 38 keywords covered in previous articles! That's 79% keywords covered. We have only 10 keywords to cover and I will be covering 1 of those in this article. We are almost done with all the basic keywords. This article will illustrate the use of the keyword instanceof . I suggest you start with Java Keywords (Part I) before proceeding further, if you have not read any of the previous articles in the Java Keyword series. Also, go back and read the one about Data Types. All of these articles are from September 2018. That should help you find them quickly. You can also use the "search" option at the top of this page. The series was written with natural progression in mind. Therefore, some of the keywords already covered may be used in code examples illustrated here. Java keyword list abstract continue for new switch assert default goto * package synchronized boolean do if private this break double implements protected ...

Before we start... Let me start by saying this: NEVER dismiss an idea without giving it any consideration. That was the mistake I made when I first encountered an article about this design pattern many years ago. I was thrown off by the name and without even attempting to find out what this design pattern was all about, I moved on to other things. That was a huge mistake and I am not afraid to admit it. I urge you not to make that mistake. And if you have already, never make that mistake again. Trust me, you will thank me later. For now, let me tell you my story and attempt to explain when to use it along with a simple example on how to implement this pattern. The Null Object Pattern By definition, the main purpose of this pattern is to have an Object-Oriented alternative to the absence of objects by creating objects that display "do nothing" behavior. That sounds like a mouthful. In simplest terms, it is meant to provide a mechanism to replace null references w...