Question

我是Java新手。我有一个HashSet方法，想知道编写以下代码的更好方法：

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;
}

做这样的事情的最有效方法是什么？

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，如果你永远不会修改你的设置，那么如果你把它作为一个常数会更有效：

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

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

Answer 2

如果要同时将所有元素添加到HashSet，可以使用Arrays.asList。请查看此问题以供参考：

Add multiple fields to Java 5 HashSet at once?

Answer 3

我建议使用Guava＆＃39; ImmutableSet Builder

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"));

如何在Java中重构这个HashSet

3 个答案: