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HashMap and LinkedHashMap CIP
Question 2
Which of the following statements is true about the HashMap class in Java?
It maintains the insertion of the Map interface
It is synchronized
It is an implementation of the Map interface
None of these
Question 3
Which of the following statements is true about the LinkedHashMap class in Java?
It does not allow null keys or values.
It is an implementation of the Map interface.
It is an implementation of the HashMap interface.
None of these
Question 4
What is the time complexity of the get() method in a HashMap in the worst case?
O(1)
O(n)
O(n logn)
O( log n )
Question 5
What is the syntax of creating a Hashmap in Java?
HashMap<k, v> map = new HashMap<>();
map<k, v> = new HashMap<>();
HashMap<k, v> map = new HashMap();
None of these
Question 6
How is LinkedHashMap declared in Java
public class LinkedHashMap<K,V>
public class LinkedHashMap<K,V> implements Map<K,V>
public class LinkedHashMap<K,V> extends HashMap<K,V> implements Map<K,V>
None of these
Question 7
What happens when a key-value pair already exists in the Map and we use put() to add the value associated with the same key?
It adds one more key-value pair of the same key.
It adds 2 values for the same key
It throws an error
It replaces the pre-existing value.
Question 8
What is the output of,
import java.util.*;
class HelloWorld {
public static void main(String[] args) {
HashMap<String, Integer> m = new HashMap<String, Integer>();
m.put("gfg", 10);
m.put("ide", 16);
m.put("courses", 25);
System.out.print(m);
System.out.print(m.size());
for( Map.Entry< String, Integer >e: m.entrySet())
System.out.print(e.getKey() + " " + e.getValue());
}
}
3courses 25gfg 10ide 16
Error
{courses=25, gfg=10, ide=16}3courses 25gfg 10ide 16
None of these
Question 9
What is the output of the code,
import java.util.*;
class HelloWorld {
public static void main(String[] args) {
HashMap<String, Integer> m = new HashMap<String, Integer>();
m.put("gfg", 10);
m.put("ide", 16);
m.put("courses", 25);
if( m.containsKey("ide"))
System.out.println("yes");
else
System.out.println("no");
m.remove("ide");
System.out.println(m.size());
}
}
no
3
yes
3
yes
2
no
2
Question 10
What is the output of the code,
import java.util.*;
class HelloWorld {
public static void main(String[] args) {
LinkedHashMap<Integer, String> m = new LinkedHashMap<>();
m.put(10, "gfg");
m.put(16, "IDE");
m.put(25, "courses");
m.remove( 25 );
m.put( 20, "practice" );
System.out.println(m);
}
}
Throws an error
{10=gfg, 16=IDE, 20=practice}
{10=gfg, 16=IDE, 25=courses, 20=practice}
None of these
There are 10 questions to complete.
