keySet() in Java

 

 

keySet() 

 

returns a set of the keys in HashTable.

 

 

 

Example Code I

import java.util.*;
 
public class Main {
 
    public static void main(String[] args) {
       
        Map<Integer, String> hash = new HashMap<>();
 
        String[] fruit = {"apple", "banana", "cherry"};
        for (int i = 0; i < fruit.length ; i++) {
            hash.put(i,fruit[i]);
        }
 
        System.out.println(hash); //{0=apple, 1=banana, 2=cherry}
        System.out.println(hash.keySet());//[0, 1, 2]
    }
}

 

 

 

Example Code II

import java.util.*;
 
public class Main {
    public static void main(String[] args) {
        String[] fruit = {"apple", "banana", "cherry"};
        String[] fruit2 = {"apple", "cherry"};
 
        Map<String, Integer> hash = new HashMap<>();
 
        for (String arg : fruit) hash.put(arg, hash.getOrDefault(arg, 0) + 1);
        for (String arg : fruit2) hash.put(arg, hash.get(arg) - 1);
        for (String key : hash.keySet()) {
            if (hash.get(key) != 0) System.out.println(key);
        }
    }
}