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
the methods for the bidimap interface are as follows −
| 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.ge.
org.apache.commons.collections4.iterablege.
org.apache.commons.collections4.pu.
java.util.ma.
example of bidimap interface
an example of bidimaptester.java is as follows −
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
when you run the code, you will see the following output −
1
one
original map: {one=1, three=3, two=2}
modified map: {three=3, two=2}
inversed map: {2=two, 3=three}