Java Basic Archives - Page 3 of 13

Introduce about text block in Java

Previously, when declaring a multi-line text in Java, for example:

Welcome to Huong Dan Java 
My name is Khanh

1 2	Welcome to Huong Dan Java My name is Khanh

We will usually declare the following:

String text = "Welcome to Huong Dan Java \n" + 
    "My name is Khanh";

1 2	String text = "Welcome to Huong Dan Java \n" + "My name is Khanh";

Result: But from Java 13 onwards, you do not need to declare so anymore. Java now supports the text blocks with the ability to declare multiple lines… Read More

Install Java JDK

6 years ago by Khanh NguyenJava Basic

To work with the Java programming language, the first thing you need to do is set up the environment to run the application with the Java JDK. In this article, I will guide you through the steps to install Java JDK! To install Java JDK,… Read More

Introduction about Bean Validation in Java

6 years ago by Khanh NguyenJava Basic

In the tutorial about @Entity and @Table annotation in JPA, I mentioned to you the concept of Java Bean, they are POJOs with at least one constructor with no parameters. We often use Java Bean to contain information of an object. To ensure that the… Read More

Switch statement in Java

6 years ago by Khanh NguyenJava Basic

The switch statement in Java is a statement used to check the value of a variable, which can have different values, depending on the value of this variable, we can define a different set of statements. For example, I have n variable that can be… Read More

Use Lambda Expression to sort elements of a List in Java

7 years ago by Khanh NguyenJava Basic

Normally, before Java 8, when we want to sort the elements of a List in Java, we will use the Comparator object. Eg:

package com.huongdanjava.javaexample;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

public class Example {

	public static void main(String[] args) {
		List<String> names = new ArrayList<>();
		names.add("Thanh");
		names.add("Khanh");
		names.add("Tan");

		Collections.sort(names, new Comparator<String>() {
		    @Override
		    public int compare(String s1, String s2) {
		        return s1.compareTo(s2);
		    }
		});

		for (String s : names) {
			System.out.println(s);
		}
	}
}

package com.huongdanjava.javaexample;

import java.util.ArrayList;

import java.util.Collections;

import java.util.Comparator;

import java.util.List;

public class Example {

public static void main(String[] args) {

List<String> names = new ArrayList<>();

names.add("Thanh");

names.add("Khanh");

names.add("Tan");

Collections.sort(names, new Comparator<String>() {

@Override

public int compare(String s1, String s2) {

return s1.compareTo(s2);

}

});

for (String s : names) {

System.out.println(s);

}

Result: From Java 8 onwards, we have another way of doing this. That is, using the sort() method of the List… Read More

Components of HotSpot JVM

7 years ago by Khanh NguyenJava Basic

Java applications run on a Java Virtual Machine (JVM) so understanding how Java applications work in the JVM will help us understand how to organize and write code more efficiently. Currently, we have a variety of JVMs built by different companies based on the JVM… Read More

Delete directory in Java

7 years ago by Khanh NguyenJava Basic

In the previous tutorial, I showed you how to create a new directory in Java. In this tutorial, I will guide you with some ways to delete a folder! The first is that we can use the File object. Deleting a directory in Java using… Read More

Constructor reference in Java

7 years ago by Khanh NguyenJava Basic

I have introduced the method reference in the previous tutorial, in this tutorial, I introduce you another new concept: constructor reference. Like the method reference, the constructor reference is used to abbreviate the Lambda Expression expression. How is it in details? Suppose you are working… Read More

Method reference in Java

7 years ago by Khanh NguyenJava Basic

Method reference is a new Java concept from version 8. It comes with Lambda Expression, which makes code writing using Lambda Expression even short but still shorter in some cases. In this tutorial, let’s learn more about the method reference in Java! OK, let’s get… Read More

Introduction about default method in Java

7 years ago by Khanh NguyenJava Basic

The default Java method introduced from Java 8 is to enable the ability to extend, improve an existing interface without breaking the previously implemented interface. How is it in details? Let’s learn together in this tutorial! OK, let’s start with the following example. For example,… Read More