Example of Library Project

ExampleLibrary.java

public class ExampleLibrary {
    
    private ExampleLibrary(String title, String message) {
        // Initialize your Library here
    }
    
    class Builder {
        private String title;
        private String message;
        
        public Builder addSomeTitle(String title) {
            this.title = title;
            return this;
        }
        
        public Builder addSomeMessage(String message) {
            this.message = message;
            return this;
        }
        
        public ExampleLibrary build() {
            return ExampleLibrary(title, message);
        }
    }
}

ExampleLibraryUserAppInit.java

public void initExampleLibrary() {
    ExampleLibrary instance = new ExampleLibrary.Builder()
      .addSomeTitle("title")
      .addSomeMessage("message")
      .build();
  }