Get next item in LinkedHashMap?

Question

I have the first key/value pair in a LinkedHashMap, which I get from a loop:

for (Entry<String, String> entry : map.entrySet()) {
    String key = entry.getKey();
    String value = entry.getValue();
    //put key value to use
    break;
}

Later on, based on an event, I need the next key/value pair in the linkedHashMap. What is the best way to do this?

Later on in the same function or where? – thattolleyguy Nov 05 '10 at 21:07 — thattolleyguy, Nov 05 '10 at 21:07

score 5 · Accepted Answer · answered Nov 05 '10 at 21:12

Get an iterator and use hasNext() and next():

...
Iterator<Entry<String, String>> it = map.entrySet().iterator();
if (it.hasNext()) {
    Entry<String, String> first = it.next();
    ...
}
...
if (eventHappened && it.hasNext()) {
    Entry<String, String> second = it.next();
    ...
}
...

score 2 · Answer 2 · answered Nov 05 '10 at 21:20

Its much easier to have the previous value if you need to compare to consecutive values.

String pkey = null; 
String pvalue = null; 
for (Entry<String, String> entry : map.entrySet()) { 
    String key = entry.getKey(); 
    String value = entry.getValue(); 

    // do something with pkey/key and pvalue/value.

    pkey = key;
    pvalue = value;
}

score 1 · Answer 3 · answered Nov 05 '10 at 21:11

Rather than for each loop, use an iterator.

Iterator it = map.entrySet().iterator();
while (it.hasNext()) {
    Map.Entry entry = (Map.Entry)it.next();
    String key = entry.getKey();
    String value = entry.getValue();
    // do something
    // an event occurred 
    if (it.hasNext()) entry = (Map.Entry)it.next();
}

Get next item in LinkedHashMap?

3 Answers3