Loading resources using getClass getResource

Question

I am trying to load an image to use as an icon in my application   The appropriate method according to this tutorial is  protected ImageIcon createImageIcon String path  String description         java net URL imgURL   getClass   getResource path       if  imgURL    null            return new ImageIcon imgURL  description         else           System err println  quot Couldn t find file   quot    path           return null           So  I placed the location of the file  and passed it as a parameter to this function   This didn t work  i e  imgURL was null  When I tried creating the ImageIcon by passing in the path explicitly  ImageIcon icon    new ImageIcon path  quot My Icon Image quot     It worked great   So the application can pick up the image from an explicitly defined path  but didn t pick up the image using getResources     In both cases  the value of the path variable is the same   Why wouldn t it work   How are resources found by the class loader  Thanks

User · Answer

getResourceAsStream   look inside of your resource folder  So the fil shold be placed inside of the defined resource-folder i e if the file reside in  src main resources properties -- gt  then the path should be  properties yourFilename  getClass getResourceAsStream  properties yourFilename

User · Answer

You can request a path in this format    package path to the resource ext   Even the bytes for creating the classes in memory are found this way   my Class - gt   my Class class   and getResource will give you a URL which can be used to retrieve an InputStream   But    I d recommend using directly getClass   getResourceAsStream      with the same argument  because it returns directly the InputStream and don t have to worry about creating a  probably complex  URL object that has to know how to create the InputStream   In short  try using getResourceAsStream and some constructor of ImageIcon that uses an InputStream as an argument   Classloaders  Be careful if your app has many classloaders  If you have a simple standalone application  no servers or complex things  you shouldn t worry  I don t think it s the case provided ImageIcon was capable of finding it   Edit  classpath  getResource is   as mattb says   for loading resources from the classpath  from your  jar or classpath directory   If you are bundling an app it s nice to have altogether  so you could include the icon file inside the jar of your app and obtain it this way

User · Answer

getClass   getResource path  loads resources from the classpath  not from a filesystem path

User · Answer

As a noobie I was confused by this until I realized that the so called  path  is the path relative to the MyClass class file in the file system and not the MyClass java file   My IDE copies the resources  like xx jpg  xx xml  to a directory local to the MyClass class  For example  inside a pkg directory called  target classes pkg   The class-file location may be different for different IDE s and depending on how the build is structured for your application   You should first explore the file system and find the location of the MyClass class file and the copied location of the associated resource you are seeking to extract   Then determine the path relative to the MyClass class file and write that as a string value with  dots  and  slashes      For example  here is how I make an app1 fxml file available to my javafx application where the relevant  MyClass class  is implicitly  Main class    The Main java file is where this line of resource-calling code is contained   In my specific case the resources are copied to a location at the same level as the enclosing package folder  That is   target classes pkg Main class and  target classes app1 fxml   So paraphrasing   the relative reference     app1 fxml  is  start from Main class  go up one directory level  now you can see the resource      FXMLLoader loader   new FXMLLoader            loader setLocation getClass   getResource     app1 fxml       Note that in this relative-path string     app1 fxml   the first two dots reference the directory enclosing Main class and the single     indicates a file extension to follow   After these details become second nature  you will forget why it was confusing

User · Answer

getResource by example   package szb testGetResource  public class TestGetResource       private void testIt             System out println  test1    TestGetResource class getResource  test css             System out println  test2    getClass   getResource  test css               public static void main String   args            new TestGetResource   testIt                output   test1  file  home szb projects test bin szb testGetResource test css test2  file  home szb projects test bin szb testGetResource test css

[java] Loading resources using getClass().getResource()

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