Commons Collections - BidiMap Interface
New Interfaces are added to supports bidirectional Map. Using bidirectional map, a key can be lookup using value and value can be lookup using key easily.
Interface Declaration
Following is the declaration for
org.apache.commons.collections4.BidiMap<K,V> interface −
public interface BidiMap<K,V>
extends IterableMap<K,V>
Methods
| Sr.No. | Method & Description |
|---|---|
| 1 |
K getKey(Object value)
Gets the key that is currently mapped to the specified value.
|
| 2 |
BidiMap<V,K> inverseBidiMap()
Gets a view of this map where the keys and values are reversed.
|
| 3 |
V put(K key, V value)
Puts the key-value pair into the map, replacing any previous pair.
|
| 4 |
K removeValue(Object value)
Removes the key-value pair that is currently mapped to the specified value (optional operation).
|
| 5 |
Set<V> values()
Returns a Set view of the values contained in this map.
|
Methods Inherited
This interface inherits methods from the following interfaces −
org.apache.commons.collections4.Get
org.apache.commons.collections4.IterableGet
org.apache.commons.collections4.Put
java.util.Map
Example of BidiMap Interface
BidiMapTester.java
import org.apache.commons.collections4.BidiMap;
import org.apache.commons.collections4.bidimap.TreeBidiMap;
public class BidiMapTester {
public static void main(String[] args) {
BidiMap<String, String> bidi = new TreeBidiMap<>();
bidi.put("One", "1");
bidi.put("Two", "2");
bidi.put("Three", "3");
System.out.println(bidi.get("One"));
System.out.println(bidi.getKey("1"));
System.out.println("Original Map: " + bidi);
bidi.removeValue("1");
System.out.println("Modified Map: " + bidi);
BidiMap<String, String> inversedMap = bidi.inverseBidiMap();
System.out.println("Inversed Map: " + inversedMap);
}
}
Output
It will print the following result.
1
One
Original Map: {One=1, Three=3, Two=2}
Modified Map: {Three=3, Two=2}
Inversed Map: {2=Two, 3=Three}