Scanner class in Java is a class that helps us to read data from many different sources such as user input when running the application, files. In this tutorial, I will show you how to read the information that the user enters using this Scanner… Read More
In the previous tutorial, we learned together how to list files and folders in a certain folder but only for the folder we want. If you want to list all the subdirectories in this directory as well, because a directory can contain many subdirectories and… Read More
Before Java 8, you can use the listFiles() method of the File class with the parameter of the directory that we want to get the list of files and directories to do this. Eg:
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File[] files = new File("/Users/khanh/Documents/code/huongdanjava.com").listFiles(); |
The return result will be a list of File objects… Read More
In Java, the concept of immutable refers to classes whose objects do not change information after they are instantiated. Normally, to declare an immutable class, we would: Declare this class as final so that no class can extend from it. Declare the fields of that… Read More
In Java, to prevent the inheritance of a certain class, we will use the final keyword to declare that class. Examples are as follows:
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package com.huongdanjava.javaexample; public final class JavaExample { public static void main(String[] args) { } class Test extends JavaExample { } } |
Class Test will not be able to inherit JavaExample class because this JavaExample class is declared with final: A need… Read More
We often use the Java server runtime to run Java web applications such as Tomcat, Jetty, … From Java version 18, by default, Java also supports us to run a server runtime using the jwebserver command. By default, the jwebserver command will run a web… Read More
A need that we often meet is how to know what version of the application we are running, so we can know what features the application is supporting up to this version. In Java, depending on what application you are using, Web application or Desktop… Read More
Java Module System was introduced by Java from Java 9 to solve some problems of Java that if you notice you will see how its necessary? NoClassDefFoundError: This error occurs while our Java program is running. The JVM cannot find the class needed to execute… Read More
Java allows us to define a class that belongs to another class, for example:
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package com.huongdanjava.javaexample; public class Application { class Builder { } } |
Class is defined inside another class, we call it nested class and this other class is called outer class. In my example above, the Builder is a nested class and… Read More
The instanceof operator in Java is an operator used to check if this object is an instance of a certain class or interface or not? The return result of this operator will be true if the object is an instance of the class you are… Read More
