NavigableMap is similar to NavigableSet. In NavigableMap we will use key value pairs to reterive the value. see the following code:
navigableMap.put(1,"tiger");
Look into the following code snippet:
package javabeat.net; import java.util.NavigableMap; import java.util.concurrent.ConcurrentSkipListMap; public class NavigableMapExample1 { public static void main(String args[]){ NavigableMap<Integer,String> navigableMap = new ConcurrentSkipListMap<Integer,String>(); navigableMap.put(1,"tiger"); navigableMap.put(2,"lion"); navigableMap.put(3,"leopard"); System.out.println(navigableMap.lowerEntry(2)); System.out.println(navigableMap.higherEntry(2)); } }
In tha bove code NavigableMap API is used for reteriving the less than and greater than value based on key. The output would be like this:
1=tiger 3=leopard
2) What will be the output of the following program?
package navmap; import java.util.HashMap; import java.util.NavigableMap; import java.util.TreeMap; public class Ques01 { public static void main(String[] args) { NavigableMap<String, String> colors = new HashMap<String, String>(); colors.put("RED", "Red"); colors.put("BLUE", "Blue"); System.out.println(colors.get("BLUE")); } }
- The program will output ‘null’.
- The program will return ‘Blue’.
- The program won’t compile because of compilation errors.
- The program will throw a run-time exception.
Answer
2) c.
The program won’t compile since the class HashMap doesn’t implement the NavigableMap interface.