地图的值是一个对象。 如何使用/迭代所有这些变量？ （Java）

Question

I have data that describes people - they all have an ID, hair color, eye color, age, etc. A People class contains those values. I made a map like this in an other class:

private static Map<Integer, People> people = new HashMap<Integer, People>();

I made a getPeople() method for it, so I could use it elsewhere.

When I'm trying to get the values of my "people" map, I get it back as a long string, like brownblue6 which is ok, because I get the right values back, but I need to use them one by one.

So let's say, I need to do something with the person's ID or get the person's hair color if that person has blue eyes.

How can I iterate through those values or get only the "eyeColor" string's value? Do I really need to use Map here or is there another easier way for this? (The things that describe people must stay in a separate class, I can't change that.)

Answer 1

It's not clear whether or not you need a map - or even what key you're using. Unless you need to look things up by key, you probably just want a List<People> - and you should probably rename your type to Person if it's meant to represent a single person per instance, which looks more likely. At that point, you could use:

for (Person person : foo.getPeople() {
    String eyeColor = person.getEyeColor();
    // Do whatever you need
}

Answer 2

Firstly, people means persons . I suspect that you might have wanted something like this:

private static Map<Integer, Person> people = new HashMap<Integer, Person>();

After that, you can use enhanced-for-loop to iterate over the map. For example:

for(Map.Entry<Integer, Person> person: people.entrySet())
{
   String hair = person.getHairColor();
   //... You can retrieve other features as well.
}

Answer 3

Since you haven't provided your class code, I'll have to guess at field names, etc., but this seems like it should accomplish what you want:

// Get the people (which are values, as opposed to keys) of the map.
Collection<Person> people = getPeople().values();

// Iterate over each person.
for (Person somePerson : people) {
    // Do something with the eye color.
    System.out.println("This eye color is " + somePerson.eyeColor);
}