Introduction to Java Collections Framework this is test

1. List 

It is an ordered collection.

it allows duplicates.

Index based access is possible.

Positional manipulation is possible.

Can Contain Null Values.

It is Resizable Dynamically.

List names = new ArrayList<>(); 
names.add("Alice"); 
names.add("Bob"); 
names.add("Alice"); 
System.out.println(names); // [Alice, Bob, Alice]
  

2. Set 

it does not allow duplicate elements. 

It has no guarantee of insertion order.

It supports null values (only one null entry allowed).

Set uniqueNames = new HashSet<>(); 
uniqueNames.add("Alice"); 
uniqueNames.add("Bob"); 
uniqueNames.add("Alice"); 
System.out.println(uniqueNames); // [Alice, Bob]
  

3. Map

It stores data in key-value pairs.

Duplicate keys are not allowed; values can be duplicated.

Provides quick access to values based on keys.

It has no guarantee of insertion order. 

Map scoreMap = new HashMap<>(); 
scoreMap.put("Alice", 90); 
scoreMap.put("Bob", 80); 
System.out.println(scoreMap.get("Alice")); // 90