Calling a Java 8 function only once when iterating a function list

Question

Is there an elegant way to store the return value of the apply() method so it won't have to be invoked more than once? Because the only way I could think of is to create a local map variable that will store the function-"return value" pairs.

@Autowired
private List<Function<String, String>> evaluators; 
//...
private String evaluate(String code) {  
    return evaluators.stream().filter(f -> f.apply(code) != null).findFirst().get().apply(code); 
}

Answer 1

Try this.

  private String evaluate(String code) {  
      return evaluators.stream()
          .map(f -> f.apply(code))
          .filter(s -> s != null)
          .findFirst().get();
  }