Java Collection How to - Remove all the elements from one Set to another

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Question

We would like to know how to remove all the elements from one Set to another.

Answer

import java.util.HashSet;
import java.util.Set;
/*from  w  w w  . ja v  a 2  s  . c  o  m*/
public class Main {
  public static void main(String[] argv) throws Exception {
    Set set1 = new HashSet();
    Set set2 = new HashSet();

    set1.removeAll(set2);
  }
}

Remove element from HashSet in Java

/*w  ww.j a va2 s  .  c  o  m*/
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

public class Main {
  public static void main(String[] args) {
    Set<Integer> set = new HashSet<Integer>();

    set.add(new Integer(1));
    set.add(new Integer(2));
    set.add(new Integer(3));
    set.add(new Integer(4));
    set.add(new Integer(5));
    set.add(new Integer(6));
    set.add(new Integer(7));
    set.add(new Integer(8));
    set.add(new Integer(9));
    set.add(new Integer(10));

    // Use iterator to display the vsetes
    System.out.println("HashSet Before: ");
    for (Iterator i = set.iterator(); i.hasNext();) {
      Integer integer = (Integer) i.next();
      System.out.println(integer);
    }

    // Remove the integer 6
    System.out.println("\nRemove integer 6");
    set.remove(new Integer(6));

    // Use iterator to display the vsetes
    System.out.println("\nHashSet After: ");
    for (Iterator i = set.iterator(); i.hasNext();) {
      Integer integer = (Integer) i.next();
      System.out.println(integer);
    }

  }
}

The code above generates the following result.

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