如何在Java中重构这个HashSet

Question

我对Java很陌生。我有一种HashSet方法，并想知道一种更好的编码方法：

public HashSet<Guitar> getGuitars() {

    HashSet<Guitar> guitarInformations = new HashSet<Guitar>();
    Guitar guitar1 = new Guitar("Gibson", 100, "1987");
    Guitar guitar2 = new Guitar("Gibson", 200, "1976");
    Guitar guitar3 = new Guitar("Gibson", 300, "1978");
    Guitar guitar4 = new Guitar("Gibson", 400, "1967");
    Guitar guitar5 = new Guitar("Gibson", 500, "1967");
    Guitar guitar6 = new Guitar("Fender", 100, "1922");
    Guitar guitar7 = new Guitar("Fender", 200, "1999");
    Guitar guitar8 = new Guitar("Fender", 300, "1986");
    Guitar guitar9 = new Guitar("Fender", 400, "1933");
    Guitar guitar10 = new Guitar("Fender",500, "1988");
    guitarInformations.add(guitar1);
    guitarInformations.add(guitar2);
    guitarInformations.add(guitar3);
    guitarInformations.add(guitar4);
    guitarInformations.add(guitar5);
    guitarInformations.add(guitar6);
    guitarInformations.add(guitar7);
    guitarInformations.add(guitar8);
    guitarInformations.add(guitar9);
    guitarInformations.add(guitar10);

    return guitarInformations;
}

做这种事最有效的方法是什么？

Answer 1

我会用：

return new HashSet(Arrays.asList(
    new Guitar("Gibson", 100, "1987"),
    new Guitar("Gibson", 200, "1976"),
    new Guitar("Gibson", 300, "1978"),
    new Guitar("Gibson", 400, "1967"),
    new Guitar("Gibson", 500, "1967")));

当然，如果您永远不会修改您的集合，如果将它作为常量，它将更有效：

 private static final Set<Guitar> GUITARS = 
   Collections.unmodifiableSet(new HashSet(Arrays.asList(
      ...

 public Set<Guitar> getGuitars() {
     return GUITARS;
 }

Answer 2

如果希望同时向HashSet添加所有元素，则可以使用Arrays.asList。请查看此问题，以供参考：

一次向Java 5 HashSet添加多个字段？

Answer 3

我建议使用番石榴的ImmutableSet生成器

public static final ImmutableSet<Guitar> GUITARS= ImmutableSet.of(
    new Guitar("Gibson", 100, "1987"),
    new Guitar("Gibson", 200, "1976"),
    new Guitar("Gibson", 300, "1978"),
    new Guitar("Gibson", 400, "1967"),
    new Guitar("Gibson", 500, "1967"));