CODEWITHSUNDEEP
java
vamosrafa
vamosrafa

Reputation: 695

method get(int) is undefined for the type Set

I have written a piece of logic, where, my goal is to select random keys from the map. The map has been assigned as a ConcurrentSkipListMap<Text,IntWritable> tuples. Also, I don't have any industrial level experience with Java, so struggling to get over this.

The piece of code is 

Set<Text> keys = tuples.keySet();
String randomKeys = keys.get(random.netInt(keys.size()))

I am not able to figure out the error statement: method get(int) is undefined for the type Set<Text>

Also, I have searched for the similar problem, and a solution do exist using List, but my key/value pairs are stored as ConcurrentSkipListMap, so not able to figure out this.

Thanks.

Upvotes: 1

Views: 14437

Answers (2)

nidomiro
nidomiro

Reputation: 830

A Set does not have an get() method, because its not array like.

you normaly can iterate through an Set with its iterator: set.iteraor().next()

The iterator interface implements the folowing methods:

public boolean hasNext()
public E next()
public void remove()

you can use it like here (in this case is an Set):

Iterator it = set.iterator();
while (it.hasNext())
{         
        String setText = (String) it.next();
        System.out.println(setText);
}

Upvotes: 0

Elliott Frisch
Elliott Frisch

Reputation: 201497

First, Set doesn't have a get() method. You could use a List. Also, it's Random.nextInt()

List<Text> keys = new ArrayList<>(tuples.keySet());
Text randomKeys = keys.get(random.nextInt(keys.size()));

Also, depending on your use-case I believe it would likely be better to Collections.shuffle(List) once and then iterate it (perhaps with a for-each loop) like

List<Text> keys = new ArrayList<>(tuples.keySet());
Collections.shuffle(keys);
for (String randomKey : keys) {
  // ...
}

Upvotes: 4

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