How to get value from gradle.properties in .class file at the time of build

I would like to get a property value from Gradle.properties in Java class. In Java, the value should be replaced at build time, and in the .jar(.class) file the value will come but not in a .java file. So that we can change the value directly in gradle.properties and no need to change the code. Is it possible to achieve?

It would be easier to answer if you told your specific use case. Also it would help to know your application, for example is it a Spring (Boot) app? In that case it would probably make more sense to use Spring Profiles for that.

Anyway, here is a possible solution:

• Create a properties file and put it in your resources folder. Define a placeholder, that gradle can replace. For example file "myapp.properties"

  greetingText=@greeting@
  

• Add the token (the text between the '@'s) to your gradle.properties:

  greeting=Hello world!
  

• Make the build.gradle replace the token with the value from gradle.properties by configuring the processResources task:

  processResources {
      inputs.file file('gradle.properties')
      filter(
              ReplaceTokens, 
              tokens: [
                      greeting: project.ext.greeting
              ]
      )
  

  }

• At runtime load the value from the properties file:

  public String getGreeting() throws IOException {
      try (
          InputStream inputStream = Thread.currentThread().getContextClassLoader().getResource("myapp.properties").openStream();
      ) {
          Properties appProps = new Properties();
          appProps.load(inputStream);
          return appProps.getProperty("greetingText");
      }
  }