What's the equivalent to a .NET SortedDictionary, in Java?

Question

If .NET has a SortedDictionary object ... what is this in Java, please? I also need to be able to retrieve an Enumeration (of elements), in the Java code .. so I can just iterate over all the keys.

I'm thinking it's a TreeMap ? But I don't think that has an Enumeration that is exposed?

Any ideas?

Answer 1

TreeMap would be the right choice. As for the Collection of all the keys (or values), any Map exposes keySet() and values() .

EDIT (to answer your question with code tags). Assuming you have a Map<String, Object> :

for (String key : map.keySet()) {
     System.out.println(key); // prints the key
     System.out.println( map.get(key) ); // prints the value
}

You can also use entrySet() instead of keySet() or values() in order to iterate through the key->value pairs.

Answer 2

TreeMap is probably the closest thing you're going to find.

You can iterate over the keys by calling TreeMap.keySet(); and iterating over the Set that is returned:

// assume a TreeMap<String, String> called treeMap
for(String key : treeMap.keySet())
{
    string value = treeMap[key];
}

It would be the equivalent of:

// assume a SortedDictionary called sortedDictionary
foreach(var key in sortedDictionary.Keys)
{
    var value = sortedDictionary[key];
}

---

You could also try the following:

// assume SortedDictionary<string, string> called sortedDictionary
foreach(KeyValuePair<string, string> kvp in sortedDictionary)
{
    var key = kvp.Key;
    var value = kvp.Value;
}

Which is the equivalent to the following .NET code:

 // assume SortedDictionary<string, string> called sortedDictionary foreach(KeyValuePair<string, string> kvp in sortedDictionary) { var key = kvp.Key; var value = kvp.Value; } 

Answer 3

你需要的是SortedMap（TreeMap）的entrySet（）方法。