import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
public class AddAllFrequencyDisjoint {
public static void main(String[] args) {
// TODO Auto-generated method stub
// initialize list1 and list2
String[] colors = {"red", "white", "yellow", "blue"};
List<String> list1 = Arrays.asList(colors);
ArrayList<String> list2 = new ArrayList<>();
list2.add("black"); // add "black" to the end of list2
list2.add("red"); // add "red" to the end of list2
list2.add("green"); // add "green" to the end of list2
list2.add("red"); // add "red" to the end of list2
list2.add("red"); // add "red" to the end of list2
System.out.print("Before addAll, list2 contains: ");
// display elements in vector
for (String s : list2)
System.out.printf("%s ", s);
Collections.addAll(list2, colors); // add colors Strings to list2
System.out.printf("%nAfter addAll, list2 contains: ");
for (String s : list2)
System.out.printf("%s ", s);
int frequency = Collections.frequency(list2, "red");
System.out.printf(
"%nFrequency of red in list2: %d%n", frequency);
// check whether list1 and list2 have elements in common
boolean disjoint = Collections.disjoint(list1, list2);
System.out.printf("list1 and list2 %s elements in common%n",
(disjoint ? "do not have" : "have"));
}
}
Console：
Before addAll, list2 contains: black red green red red
After addAll, list2 contains: black red green red red red white yellow blue
Frequency of red in list2: 4
list1 and list2 have elements in common
