AbstractMap.SimpleEntry<K, V> is used to maintain a key and a value entry. The value can be changed using the setValue method. This class facilitates the process of building custom map implementations.
hashCode() method of AbstractMap.SimpleEntry<K, V> return the hash code value for this map entry.
The hash code for the map entry e can be calculated by:
(e.getKey()==null ? 0 : e.getKey().hashCode()) ^ (e.getValue()==null ? 0 : e.getValue().hashCode())
Syntax:
public int hashCode()
Parameters: This method accepts nothing.
Return value: This method return the hash code value for this map entry.
Below programs illustrate hashCode() method:
Program 1:
// Java program to demonstrate// AbstractMap.SimpleEntry.hashCode() method  import java.util.*;import java.util.AbstractMap.SimpleEntry;  public class GFG {      @SuppressWarnings({ "unchecked", "rawtypes" })    public static void main(String[] args)    {          // create a ArrayList of Map        ArrayList<AbstractMap                      .SimpleEntry<Integer, Integer> >            arrayList            = new ArrayList<AbstractMap                                .SimpleEntry<Integer, Integer> >();          // add values        arrayList.add(new AbstractMap.SimpleEntry(0, 123));        arrayList.add(new AbstractMap.SimpleEntry(1, 130));        arrayList.add(new AbstractMap.SimpleEntry(2, 994));          // print keys        for (int i = 0; i < arrayList.size(); i++) {              // get map from list            AbstractMap.SimpleEntry<Integer, Integer>                map                = arrayList.get(i);              // get value from map using hashCode()            int value = map.hashCode();              System.out.println("HashCode = " + value);        }    }} |
Output:
HashCode = 123 HashCode = 131 HashCode = 992
Program 2:
// Java program to demonstrate// AbstractMap.SimpleEntry.hashCode() method  import java.util.*;  public class GFG {      @SuppressWarnings({ "unchecked", "rawtypes" })    public static void main(String[] args)    {          // create a ArrayList of Map        ArrayList<AbstractMap                      .SimpleEntry<String, String> >            arrayList            = new ArrayList<AbstractMap                                .SimpleEntry<String, String> >();          // add values        arrayList.add(new AbstractMap                          .SimpleEntry(" 001AB ", " Emp 1"));        arrayList.add(new AbstractMap                          .SimpleEntry(" 011AC ", " Emp 2"));        arrayList.add(new AbstractMap                          .SimpleEntry(" 111AD ", " Emp 3"));        arrayList.add(new AbstractMap                          .SimpleEntry(" 101BE ", " Emp 4"));        arrayList.add(new AbstractMap                          .SimpleEntry(" 110CE ", " Emp 5"));          // print keys        for (int i = 0; i < arrayList.size(); i++) {              // get map from list            AbstractMap.SimpleEntry<String, String>                map                = arrayList.get(i);              // get hashcode value from map using hashCode()            int value = map.hashCode();              System.out.println("hashCode = " + value);        }    }} |
Output:
hashCode = -873386249 hashCode = -874293612 hashCode = -910934441 hashCode = -910552137 hashCode = -910906733
References: https://docs.oracle.com/javase/10/docs/api/java/util/AbstractMap.SimpleEntry.html#hashCode()
