To check whether a HashSet contains another, use the contains() method.
Set the first HashSet
String strArr[] = { "P", "Q", "R" }; Set set1 = new HashSet(Arrays.asList(strArr));
Set the second HashSet
String strArr = new String[] { "P", "Q"}; Set set2 = new HashSet(Arrays.asList(strArr));
Check now
set1.containsAll(set2))
The following is an example to check if a HashSet collection in Java contains another Collection
import java.util.Arrays; import java.util.HashSet; import java.util.Set; public class Demo { public static void main(String[] a) { String strArr[] = { "P", "Q", "R" }; Set set1 = new HashSet(Arrays.asList(strArr)); strArr = new String[] { "P", "Q"}; Set set2 = new HashSet(Arrays.asList(strArr)); System.out.println(set1.containsAll(set2)); strArr = new String[] { "T", "U"}; Set set3 = new HashSet(Arrays.asList(strArr)); System.out.println(set1.containsAll(set3)); } }
The following is the output
true false