gistfile1.java

public class ListBuilder {
  
  private final StringBuilder b = new StringBuilder();
  public ListBuilder li(String s) {
    if (s!=null && !s.trim().isEmpty()) {
      b.append("<li>"); b.append(s); b.append(</li>);
    }
    return this;
  }
  public String toString() {
    return b.toString();
  }
  
  public static void main(String[] args) {
    String s = new ListBuilder()
      .li(rMap.get("a")
      .li(rMap.get("b")
      .li(rMap.get("c")
      .toString();
  
    System.out.println(s);
  }
}