Test test

#24 Collect of key/value pairs

#25 coantainsKyey(k), put(K, V), keySet() . Same type for k and V

#26 map.size()

#27
import java.util.HashMap;

 
public class MapTester
{
   
    private HashMap<String, String> book;

    
    public void enterNumber(String name, String number)
    {
        book.put(name, number);
       
    }

    
    public String lookupNumber(String name)
    {
        // put your code here
        return book.get(name);
    }
    
#28 Replacces the old value

#29 entries stay but different keys allowed

#30. map.containsKey("key");

#31 null

#32 for(String key : map.keySet()) {
    System.out.println(key);
}





#34 HashSet: unique unordered, ArrayList: ordered duplicates allowed, index access

#35 HashSet: unordered, duplicates removed; ArrayList: ordered, duplicates kept.

#36 Multiple spaces can create empty words unless you split