Array Conversion Error in Generic Data Processing

import java.util.ArrayList;

public class DataProcessor {
    public ArrayList<Integer> processGenericData(ArrayList data) {
        ArrayList<Integer> processedData = new ArrayList<>();
        for (Object obj : data) {
            processedData.add((Integer) obj);
        }
        return processedData;
    }
}

public class Main {
    public static void main(String[] args) {
        DataProcessor dp = new DataProcessor();
        ArrayList data = new ArrayList();
        data.add("1");
        data.add("2");
        System.out.println(dp.processGenericData(data));
    }
}