In a data structure (that accepts duplicate elements), an element can exist any number of times as in the case of ArrayList etc. The **frequency()** method is useful to find out how many times the same element exist in a data structure.

Following is the method signature

**static int frequency(Collection col1, Object obj1):**Checks how many times**obj1**exists in Collection**col1**; returns as an integer value.

###### Example on How many times element occurs with frequency()

```
import java.util.*;
public class CollectionsFrequency
{
public static void main(String args[])
{
ArrayList myList = new ArrayList();
myList.add(10);
myList.add(20);
myList.add(10);
myList.add(20);
myList.add(30);
myList.add(10);
System.out.println("Elements of ArrayList: " + myList);
int num = Collections.frequency(myList, 10);
System.out.println("\nNo. of times 10 exists: " + num);
System.out.println("No. of times 20 exists: " + Collections.frequency(myList, 20));
System.out.println("No. of times 30 exists: " + Collections.frequency(myList, 30));
}
}
```

Output screenshot on How many times element occurs with frequency()

ArrayList myList = new ArrayList();

myList.add(10); myList.add(20);

myList.add(10); myList.add(20);

myList.add(30); myList.add(10);

An ArrayList object **myList** is created and added with the elements **10** (repeated 3 times), **20** (repeated 2 times) and **30** (occurs only once).

int num = Collections.frequency(myList, 10);

System.out.println(“\nNo. of times 10 exists: ” + num);

The **frequency()** method returns (as integer value) the number of times element **10** exist in **myList**. It prints 3 as 10 exists three times.

nageswararaothank u