Maven shade plugin relocate file to main folder

I am using maven-shade-plugin version 3.2.1 to include/exclude some classes. I am trying to relocate files inside a folder to main folder in a jar.

I am using maven-shade-plugin version 3.2.1 to include/exclude some classes. I am trying to relocate files inside a folder to main folder in a jar.

<configuration>
        <filters>
                ...
        </filters>
        <relocations>
                <relocation>
                        <pattern>org/example</pattern>
                        <shadedPattern>org/example/example2</shadedPattern>
                </relocation>
        </relocations>
</configuration>

If I use it as above, it moves files under org.example to org.example.example2 (just to make sure it is working). If I use just "/", then it creates folder and subfolder with empty names and places files under them. And nothing happens if i keep </shadedPattern> empty.

I want to place files in the main directory but i am not able to do it so far.

Is there any way to achieve this through shade plugin or with something else?

Thanks

How to import an existing Maven project into IntelliJ IDEA?

How to import an existing Maven project into IntelliJ IDEA?

This tutorial explains how to import an existing Maven project into IntelliJ IDEA and how to create a running configuration for a Maven goal. This is useful, for example, when using the Jetty Maven plugin that allows you to quickly deploy and run a Java web application using this popular server.

This tutorial explains how to import an existing Maven project into IntelliJ IDEA and how to create a running configuration for a Maven goal. This is useful, for example, when using the Jetty Maven plugin that allows you to quickly deploy and run a Java web application using this popular server.

Maven is a project management tool that goes beyond dependency management. See Learning Maven Concepts to learn more.

Download an Existing Maven Project

This tutorial uses a Maven archetype that generates a web application with a preconfigured Jetty Maven Plugin in it:

mvn -B archetype:generate -DarchetypeGroupId=com.vaadin -DarchetypeArtifactId=vaadin-archetype-application -DarchetypeVersion=LATEST -DgroupId=org.test -DartifactId=webapp -Dversion=1.0-SNAPSHOT

NOTE: If you prefer, you can generate a ZIP file with the project at https://vaadin.com/start/latest or https://start.vaadin.com. Make sure you select the Plain Java Servlet option before downloading the project.

The project should include a directory with a Maven project in it:

NOTE: You need Node.js installed on your computer to compile the example application.

Import the Project

There are several ways to import a Maven project in IntelliJ IDEA. The most common approach is to open the pom.xml file directly. You can do it in the welcome screen by clicking Open:

NOTE: Import Project gives you more options to tweak the import process. However, this is out of the scope of this tutorial.

Select the pom.xml file of the Maven project you want to import and click Open as Project.

NOTE: The welcome window is only shown when you close all projects in IntelliJ IDEA. If you don’t want to close your currently opened projects, you can select File > Open on the menu instead.

Running Maven Goals

IntelliJ IDEA has excellent integration with Maven. You can run common commands such as mvn install or mvn jetty:runwithout having to leave the IDE.

Open the Maven view by clicking the corresponding option on the left side of the IntelliJ IDEA window:

This view shows all the available Maven projects and their build phases and build goals. Let’s say you want to run mvn install. To do that, expand the project tree in the Maven view to show the corresponding lifecycle phase and then double-click install:

You’ll see how IntelliJ IDEA executes the install build phase (and all the previous phases in the Maven’s default lifecycle) that downloads dependencies and copies the generated artifacts into your local Maven repository, among other things.

You can use a similar approach to run any Maven goal. For example, you can double-click the jetty:run goal in the Plugins sub-tree to deploy and run the web application implemented in the project you imported. Similarly, if you are using Spring, you can double-click spring-boot:run to run the application.

Creating a Running Configuration

Since using the jetty:run goal could be a frequent task during the development of a Java web application, you may prefer to create a running configuration for it.

A running configuration is a shortcut to run a specific task from within the IDE. Let’s create a running configuration for the jetty:run Maven goal to make it simpler to run the web application.

Right-click the jetty:run option in the Maven view and select Create 'webapp [jetty:run]':

For simplicity, change the name of the configuration to Run on Jetty and click OK:

NOTE: If you are using a multi-module Maven project, make sure you select the correct module when creating the running configuration.

You should see the new option on the top right corner of IntelliJ IDEA:

Now you can deploy and run the web application by clicking the run (or the debug) icon in the toolbar:

NOTE: If you use the Vaadin project used in the tutorial, you can invoke the web application at http://localhost:8080.

That’s it. Now you can use IntelliJ IDEA to develop your Maven application!

Java 12 and IntelliJ IDEA

Java 12 and IntelliJ IDEA

Java 12 and IntelliJ IDEA. In this article, we’ll cover the pain points of using existing switch statements, define switch expressions, and explain why they are good for you.

With switch expressions, Java 12 is enhancing one of its basic language constructs – switch – to improve everyday coding experience for developers. Benefits are multi-fold. As compared to the ‘traditional’ switch constructs, switch expressions can return a value. The ability to define multiple constants with a switch branch, and improved code semantics, makes it concise. By removing default fall-through switch branches, you are less likely to introduce a logical error in a switch expression.


Let’s get started.


Traditional switch constructs

If you think of a switch construct as a multi-way condition, using an expression seems to be a better fit. However, switch could only be used as a statement until now. The current switch syntax is constrained and verbose. It often leads to error-prone code that is difficult to debug.

Here’s an example that uses a switch statement to calculate the height of a chair, based on the size value passed to it:

public enum Size {S, M, L, XL};
public class Chair {
    public void calcHeight(Size size) {
        int height = 0; 
        switch (size) {
            case S:
                height = 18;
            case M:
                height = 20;
                break;
            case L:
                height = 25;
                break;
        }
    }
}

The preceding code has multiple issues:

  • Repetitive break and assignment statements add noise to code.
  • Code verbosity makes it difficult to comprehend the code.
  • Default fall-through in switch branches sneaks in a logical error – the missing break statement for case label S lets the control fall through to case label M. This results in assignment of 20 instead of 18 to height when you execute calcHeight(Size.S).
Switch expressions

Let’s rewrite the preceding example using a switch expression. In IntelliJ IDEA, you can use Alt+Enter on the switch keyword to see the suggestions. Select ‘Replace with enhanced ‘switch’ statement’ to convert the traditional switch statement to a switch expression:

The preceding code offers multiple benefits:

  • Code in a switch branch is concise and easy to read. You define what to execute to the right of ->.
  • Switch branches can return a value, which can be used to assign value to a variable.
  • Switch branches don’t need a break statement to mark their end. In absence of a break statement, the control doesn’t fall through the switch labels – which helps avoid logical errors.
Returning value vs. executing statements

When you aren’t using a switch expression to return a value, a switch branch can choose to execute a statement or block of statements, or even throw an exception:

public enum Size {S, M, L, XL};
public class NotReturningValueFromSwitchLabel {
    public void calcHeight(Size size) {
        int height = 0; 
        switch (size) {
            case S -> height = 18;
            case M -> { 
                           height = 20; 
                           System.out.println(height);
                      }
            case L -> height = 25;
        }
    }
}
Handling all possible argument values

When you are using a switch expression to return a value, it should be able to handle all possible values that you could pass to it as an argument. For instance, if you miss a case label corresponding to an enum constant, IntelliJ IDEA detects it. It offers to insert the specific case label or default case label.

By default, IntelliJ IDEA inserts a default value depending on the variable type. You can edit the placeholder value:

Types other than an enum can have infinite values. When you pass types like byte, short, int, or String and miss including the default label, IntelliJ IDEA can detect and fix it:


Define multiple constants in the same case label

Unlike switch statements, switch expressions allow you to define comma-separated multiple constants in a case label. This cuts down code redundancy – you can execute the same code for all case labels.

If you define redundant code for your case labels in a switch expression, IntelliJ IDEA can fix it for you:


Local variables and break statements in switch branches

With switch expressions, you can define local variables in switch branches. The block must include a break statement specifying the value to return:

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enum Size {S, M, L, XL};

public class LocalVariablesWithSwitch {
public void assignValue(Size size) {
int height = 0;
height = switch(size) {
case S -> 18;
case M -> {
int weight = 19;
break (weight > 10 ? 15 : 20);
}
case L, XL -> 25;
};
}
}

The case label for value M defines a block statement. A block can also define local variables (weight in this case). The scope and accessibility of the local variable weight is limited to the case label M. Notice how a switch expression uses a break statement to return a value.

Just in case you miss defining a return value for a switch branch, IntelliJ IDEA underlines the keyword case. When you hover the mouse pointer over it, you can view the message about the missing return value:


Preview language feature

Switch expressions is a preview language feature. This essentially means that even though it is complete, it has a possibility of not being confirmed as a permanent feature in a future Java release. This happens for a reason.

Java runs on billions of devices and is used by millions of developers. Risks are high for any mistake in a new Java language feature. Before permanently adding a language feature to Java, the architects of Java evaluate what the developers have to say about it – how good or bad it is. Depending on the feedback, a preview feature might be refined before it’s added to Java SE, or dropped completely. So, if you have any feedback on Switch expressions, please share it here.


IntelliJ IDEA Configuration

Since Switch expressions is a Java 12 language feature, please download and install OpenJDK 12 and configure it to use with IntelliJ IDEA:

Java is evolving and switch expressions is one of the welcome changes in Java 12.

Happy Coding!


Originally published by Mala Gupta at https://blog.jetbrains.com

Main class not found in project IntelliJ IDEA: Java Application

IntelliJ does not find a main class in my Java application project. The project was cloned from a git repository so had no run configuration. I go to Edit Configurations, add a new Application template, go to Main class: and it says "No matches found in project".

IntelliJ does not find a main class in my Java application project. The project was cloned from a git repository so had no run configuration. I go to Edit Configurations, add a new Application template, go to Main class: and it says "No matches found in project".

So, manually searching through the hierarchy I find the .java file that contains the main function but it will not accept it as the main class. I've pasted the file below to prove that it has the correct main function.

public class AdvanceWarsGameHandler implements IGame
{
private Image mImage;
private String mTitle;

public AdvanceWarsGameHandler()
{
    mTitle = "Advance Wars Game";
    mImage = new Image("/OffBrandCerealOopsAllCarries2-01.png");
}

//Game logic unrelated to graphics goes here
@Override
public void update(Game game, float deltaTime) 
{

}

//Update, but for graphics
@Override
public void render(Game game, Renderer renderer) 
{
    renderer.drawImage(mImage, game.getInput().getMouseX(), game.getInput().getMouseY());
}

 public static void main(final String args[])
{
    //Creating and starting an instance of AdvanceWarsGameHandler
    AdvanceWarsGameHandler advancewars = new AdvanceWarsGameHandler();
    Game myGame = new Game(advancewars);
    myGame.start();
}

public String getTitle()
{
    return mTitle;
}

}

So the question is, why is the IntelliJ project not recognizing the main function in this file, or what is IntelliJ looking for as the "Main class" of an application?