getResource() is returning null with Gradle project

问题

I'm aware there are several other questions regarding this...

Class.getResource() returns null

Java - class.getResource returns null

Calling context.getResources() returns null

getClassLoader().getResource(filepath) returns a null pointer

But my problems seems to be a bit different because I seem to have all of the necessary things to NOT have this problem.

The code:

 this.getClass().getResource("checkstyle_whitespace.xml"); // null

The issue is that I've verified my classpath by inspecting the class loader in the debugger. Here's what I am seeing:

 27 = {URL@1235} "file:/Users/dennis/Documents/Development/java/java-grader/build/classes/main/"
 28 = {URL@1236} "file:/Users/dennis/Documents/Development/java/java-grader/build/resources/main/"

Blow is a quick tree of my directory structure. See build/resources and src/main/resources. The files are being copied when gradle builds my project.

├── build
│   ├── classes
│   │   ├── main
│   │   │   └── javaGrader
│   │   └── test
│   │       └── javaGraderTest
│   └── resources
│       └── main
│           ├── checkstyle_whitespace.xml
│           └── grammars
├── src
│   ├── main
│   │   ├── java
│   │   │   └── javaGrader
│   │   └── resources
│   │       ├── checkstyle_whitespace.xml
│   │       └── grammars
│   └── test
│       ├── java
│       │   └── javaGraderTest
│       └── resources
│           └── mini_test
├── target
│   ├── classes
│   ├── generated-sources
│   │   └── annotations
│   └── generated-test-sources
│       └── test-annotations
└── test_assets

From what I understand, the files should be accessible because they're in build. Correct me if I am wrong...

回答1:

If you pass a resource path that doesn't start with a / to Class.getResource(), the class loader looks for the resource in the package of the class. Not at the root. Your code should be

this.getClass().getResource("/checkstyle_whitespace.xml")

this.getClass().getClassLoader().getResource("checkstyle_whitespace.xml")

回答2:

Create a folder called "resources" in the same Location that java folder exist in the main folder of the project. and locate all the images and other resources into the "resources" folder. the get those like this

new ImageIcon(getClass().getClassLoader().getResource("image.png"));

来源：https://stackoverflow.com/questions/35861606/getresource-is-returning-null-with-gradle-project

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java

gradle

resources

classpath