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SCJP Module-9 Question-5

The Sample program given below will check your understanding of ConcurrentSkipListMap in Collection framework.

Given below the sample code :

import java.util.NavigableMap;
import java.util.concurrent.ConcurrentSkipListMap;
public class CheckSize {
public static void main(String... args) {
NavigableMap <Integer, String>nM = new ConcurrentSkipListMap<Integer, String>();
nM.put(4, "Wednesday");
nM.put(5, "Thursday");
nM.put(6, "Friday");
nM.put(1, "Sunday");
nM.put(2, "Monday");

What will be the output of the above ?

1. Compile error

2. 2

3. null

4. 4




ceilingKey() : Returns the least key greater than or equal to the given key, or null if there is no such key.


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