Literally, just turns your sentences into subreddits. That's about it!

RedditFormatter.java

public class RedditFormatter {
	private String[] input;
	
    public RedditFormatter(String[] input) {
        this.input = input;
   	}
	
    public String format() {
        String result = String.join(" r/", this.input);    
        System.out.println("r/" + result);

        return result;
    }
}