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Retrieve all the keys from HashMap in Java
Let’s say the following is our HashMap −
HashMap<Integer, String>map = new HashMap<Integer, String>(); map.put(10, "A"); map.put(20, "B"); map.put(30, "C"); map.put(40, "D"); map.put(50, "E"); map.put(60, "F"); map.put(70, "G"); map.put(80, "H");
To retrieve all the keys, iterator through each and every key-value pair −
Set<Integer>set = map.keySet();
Iterator<Integer>i = set.iterator();
while (i.hasNext()) {
Integer res = i.next();
System.out.println(res + ": " + map.get(res));
}Example
import java.util.HashMap;
import java.util.Iterator;
import java.util.Set;
public class Demo {
public static void main(String[] args) {
HashMap<Integer, String>map = new HashMap<Integer, String>();
map.put(10, "A");
map.put(20, "B");
map.put(30, "C");
map.put(40, "D");
map.put(50, "E");
map.put(60, "F");
map.put(70, "G");
map.put(80, "H");
Set<Integer>set = map.keySet();
Iterator<Integer>i = set.iterator();
while (i.hasNext()) {
Integer res = i.next();
System.out.println(res + ": " + map.get(res));
}
}
}Output
80: H 50: E 20: B 70: G 40: D 10: A 60: F 30: C
Updated on: 30-Jul-2019
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