Can't translate foreach from C# to Java

Question

I'm trying to translate a Boolean Retrieval Model search engine and can't translate this piece of code to Java.

C#:

foreach(KeyValuePair<string ,List<string>> p in documentCollection){}

Java:

for(Map<String, ArrayList<String>> p : documentCollection){}

Unfortunately Java giving me this error:

for-each not applicable to application type

Thanks in advance!

@rapharel documentCollection should be instance of java.lang.Iterable or array — Kumar Abhinav, Aug 20 '15 at 12:27
@JFPicard public static Map> documentCollection = new HashMap<>(); — Rapharel, Aug 20 '15 at 13:13

score 6 · Accepted Answer · answered Aug 20 '15 at 12:31

There is a difference between the way a collection interface is implemented by C#'s IDictionary<K,V> and Java's Map<K,V>. In C#, the collection itself can be enumerated for key-value pairs; in Java, you must call a method to obtain a key-value set, which is called entrySet():

for (Map.Entry<String,ArrayList<String>> p : documentCollection.entrySet()) {
    ...
}

Note that in Java you iterate Map.Entry<K,V> objects instead of C#'s KeyValuePair<K,V>.

Can't translate foreach from C# to Java

1 Answers1