Say I am iterating over a Map in Java... I am unclear about what I can to that Map while in the process of iterating over it. I guess I am ... |
I have a custom made class called Graph in which I use adjacency lists. To be more specific, I have an array of hash maps where each hash map contains all ... |
I am a newbie, I have a question.
I have a map. I have to loop through the map and build the iterator.
Example:
public Iterable<Test> getTests(Map<String, Test> testMap,
Set<String> strings)
{
...
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I have a TreeMap that maps String keys to a custom City class. Here is how it is instantiated:
TreeMap<String, City> nameDictionary = new TreeMap<String, City>(new CityNameComparator());
CityNameComparator implementation:
...
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I am making an encrypt and decrypt program for my programming class, however I am a year ahead of the group so I thought I'd simplify things by using what I ... |
In the following code snippet, does the check for dic.isEmpty() result in any performance improvement?
for (Map<String, String> dic : dics) {
if ...
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Usually we write this to get the keys and values from a map.
Map m=new HashMap();
Set s=map.entrySet();
Iterator i=s.iterator()
while(s.hasNext()){
Map.Entry m= (map.Entry) s.next();
System.out.println(""+m.getKey()+""+ m.getValue());
}
Why do we ... |
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I have a list of map entries, and I need an iterable that returns the keys of the maps.
Of course, we could be naive and copy over into a ... |
I have a map and this contains objects, lets say of type 'Apple'. I currently have an iterator but the only thing I seem to be able to call is the ... |
I have a variable like:
Collection<Map<String, String>> allFieldValues;
In this variable I have all the data of a sqlite Table, each map of the collection represents a row of the table.
Now ... |
I'm looking to avoid a ConcurrentModificationException where the functionality is to iterate over an expanding set (there are no removes), and the add operations are being done by different threads.
I ...
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I found some sample code of java nio:
ServerSocketChannel server = ServerSocketChannel.open();
Selector selector = Selector.open();
server.socket().bind(new InetSocketAddress(8080));
server.configureBlocking(false);
server.register(selector, SelectionKey.OP_ACCEPT);
while(true) ...
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I'm having a strange problem with the following code works.
Map<String, Object> map = new HashMap<String, Object>();
for(Entry<String, Object> entry : map.entrySet()) {
//
}
while the code below does not compile.
Map ...
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Im trying to iterate through a Treemap of the class Tile() using:
Map map = new TreeMap();
Iterator itr = world.map.values().iterator();
while(itr.hasNext()){
Tile t = ???;
...
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Today when tying to discover a bug I found the TreeMap iterator behavior a little strange when removing objects. In fact has I tested different uses, in a simple example:
...
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Dear Ranchers: I'm working on an assignment that uses a SortedMap implemented as a TreeMap to store a collection of objects. Part of the assignment is to use four buttons (first, previous, next and last) to retreive the objects from the collection. I have no problem with first and last but am having difficulty with both next and previous. Here is ... |
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What do you mean, access Map.Entry? Do you mean that you iterate over the entrySet() each time? That's how it works. There are actually three views you can use: keySet() for only the keys, values() for only the values and entrySet() for both. With entrySet() you need to have something that also contains both, and that's Map.Entry. That's why the iterator ... |
Okay, this is going to be *really* difficult to explain, but here's my best shot. stuff.entrySet().iterator() returns an Iterator, where T is the concrete type (or capture) of the entry set. Your variable expects an Iterator. So X and T need to be *exactly* the same type. Here, X is Entry, and T is Entry. This is ... |
ejp wrote: That's rather out of date. It is how Hashtable works, but as regards HashMap it isn't. The keySet() iterator and the values() iterator are both written in terms of the entrySet() iterator. There is no skipping over unused slots. Out of date? In that case there's been a recent advance in hashed data structures I've missed. Or the HashMap ... |
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