The collections api - Data Structures and Problem Solving Using Java - page 270

1 package weiss.util;
2
3 /**
4 * Map interface.
5 * A map stores key/value pairs.
6 * In our implementations, duplicate keys are not allowed.
7 */
8 public interface Map<KeyType,ValueType> extends java.io.Serializable
9 {
10 /**
11 * Returns the number of keys in this map.
12 */
13 int size( );
14
15 /**
16 * Tests if this map is empty.
17 */
18 boolean isEmpty( );
19
20 /**
21 * Tests if this map contains a given key.
22 */
23 boolean containsKey( KeyType key );
24
25 /**
26 * Returns the value that matches the key or null
27 * if the key is not found. Since null values are allowed,
28 * checking if the return value is null may not be a
29 * safe way to ascertain if the key is present in the map.
30 */
31 ValueType get( KeyType key );
32
33 /**
34 * Adds the key/value pair to the map, overriding the
35 * original value if the key was already present.
36 * Returns the old value associated with the key, or
37 * null if the key was not present prior to this call.
38 */
39 ValueType put( KeyType key, ValueType value );
40
41 /**
42 * Removes the key and its value from the map.
43 * Returns the previous value associated with the key,
44 * or null if the key was not present prior to this call.
45 */
46 ValueType remove( KeyType key );

figure 6.36
A sample Map
interface (part 1)