在哈希图中获取所有元素的最佳方法是什么？

Question

I know I can use .values() and .keyset() to get the respective keys/values on their own (from a hashmap). I am trying to get them together and return that in a get method.

Could I use entryset() to get an entry, but do it in a loop to produce an array list of entryset's and then return that? Not sure if that is the best way though. Any advice?

Answer 1

The entrySet() method already returns a collection of all of the entries (key/value pairs) in the map, not just a single entry. I think you want to just call this once and use the set that it returns instead of calling it in a loop and populating a list.

Answer 2

entrySet() returns a Set of all entries of HashMap.

import java.util.HashMap;

import java.util.Set;

public class HashMapEntrySet {

public static void main(String[] arr) {

/* Create object of HashMap */

HashMap<Integer, String> obHashMap = new HashMap<Integer, String>();

/* Strore value in HashMap */

obHashMap.put(new Integer(1), "AAA");

obHashMap.put(new Integer(2), "BBB");

obHashMap.put(new Integer(3), "CCC");

obHashMap.put(new Integer(4), "DDD");

obHashMap.put(new Integer(5), "EEE");

/* Create a set of keys of hashmap */

Set obEntrySet = obHashMap.entrySet();

System.out.println("Set of entries : " + obEntrySet); } }

Answer 3

Use entrySet() on the Map to get a set of ALL entries in the Map . You can either return the whole set or iterate over it if additional manipulations need to be made.