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AbstractMap.SimpleEntry getKey() Method in Java with Examples
  • Last Updated : 27 Jun, 2019

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.
getKey() method of AbstractMap.SimpleEntry<K, V> returns the key corresponding to this entry.

Syntax:

public K getKey()

Parameters: This method accepts nothing.

Return value: This method returns the key corresponding to this entry.

Below programs illustrate getKey() method:
Program 1:






// Java program to demonstrate
// AbstractMap.SimpleEntry.getKey() 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 key from map.getKey();
            int key = map.getKey();
  
            System.out.println("Key " + key);
        }
    }
}
Output:
Key 0
Key 1
Key 2

Program 2:




// Java program to demonstrate
// AbstractMap.SimpleEntry.get() 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 key from map.getKey()
            String key = map.getKey();
  
            System.out.println("Key " + key);
        }
    }
}
Output:
Key  001AB 
Key  011AC 
Key  111AD 
Key  101BE 
Key  110CE

References: https://docs.oracle.com/javase/10/docs/api/java/util/AbstractMap.SimpleEntry.html#getKey()

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