Java Collection class list Intersection

The mathematical definition of the set intersection is as follows:

AAndBIntersection writing"ABytesB". Form:

XBelongABytesBWhen and only when

• XBelongA, And
• XBelongB.

The Java Collection class list also provides a built-in method to calculate the intersection of the two list sets.

The method is as follows:

public boolean retainAll(Collection<?> c)

Subclass must implement this method.

The following code uses the subclass arraylist as an example:

 

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01	public class ListDemo {

02

03

/**

04	* @param args

05

*/

06	public static void main(String[] args) {

07	List<String> sList = new ArrayList<String>();

08	List<String> sList2 = new ArrayList<String>();

09	sList.add("1");

10	sList.add("2");

11	sList.add("3");

12	sList.add("4");

13

14	sList2.add("1");

15	sList2.add("3");

16	sList2.add("5");

17

18	sList.retainAll(sList2);

19

20	for(String s : sList){

21	System.out.println(s);

22

}

23

}

24

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}

Output: 1
3