Question

Question 11 pts

Which of the following is true about a Map?

A Map stores <key,value> pairs

Duplicate keys are not allowed in a Map.

A Map can be thought of as a "lookup table" or "dictionary"

All of the above

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Question 21 pts

Assume that the following code executes:

HashMap<String, Point> places = new HashMap<String, Point>();
places.put( "origin", new Point() );
places.put( "east", new Point( 100, 0 ) );
places.put( "south", new Point( 0, -100 ) );
places.put( "northwest", new Point( -100, 100 ) );
places.put( "east", new Point( 200, 0 ) );

What value is returned by the following method call?

places.size()

0

1

4

5

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Question 31 pts

Assume that the following code executes:

HashMap<String, Point> places = new HashMap<String, Point>();
places.put( "origin", new Point() );
places.put( "east", new Point( 100, 0 ) );
places.put( "south", new Point( 0, -100 ) );
places.put( "northwest", new Point( -100, 100 ) );
places.put( "east", new Point( 200, 0 ) );

What value is returned by the following call?

places.get( "south" )

a Point object located at (0.0, -100.0)

a Point object located at (0.0, 0.0)

a Point object located at (100.0, 0.0)

null

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Question 41 pts

Assume that the following code executes:

HashMap<String, Point> places = new HashMap<String, Point>();
places.put( "origin", new Point() );
places.put( "east", new Point( 100, 0 ) );
places.put( "south", new Point( 0, -100 ) );
places.put( "northwest", new Point( -100, 100 ) );
places.put( "east", new Point( 200, 0 ) );

What value is returned by the following method call?

places.get( "east" )

a Point object located at (0.0, 0.0)

a Point object located at (100.0, 0.0)

a Point object located at (200.0, 0.0)

null

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Question 51 pts

Assume that the following code executes:

HashMap<String, Point> places = new HashMap<String, Point>();
places.put( "origin", new Point() );
places.put( "east", new Point( 100, 0 ) );
places.put( "south", new Point( 0, -100 ) );
places.put( "northwest", new Point( -100, 100 ) );
places.put( "east", new Point( 200, 0 ) );

What value is returned by the following method call?

places.get( "north" )

a Point object located at (0.0, 0.0)

a Point object located at (100.0, 0.0)

a Point object located at (0.0, 100.0)

a Point object located at (-100.0, 100.0)

null

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Question 61 pts

What is an activation record?

The place keeps track of what objects the program has instantiated.

The place that keeps track of what methods each class contains.

The place where local variables and parameters are stored as a method is executing.

The place that keeps track of new class definitions.

Answer 1

Answer 11:
A Map stores <key,value> pairs
Answer 21:
5 as we have added 5 pairs
Answer 31:
a Point object located at (0.0, -100.0)
as south key has the value with 0, -100
Answer 41:
a Point object located at (200.0, 0.0)
as east has the value as 200,0.0.
east it is inserted twice so it will have the recently added value
Answer 51:null
As we dont have any key as north
Answer 61:
The place where local variables and parameters are stored as a method is executing.

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