Question

3. Create a program named TestArrayList, and declare an ArrayList with an initial capacity of 10. Insert one copy of the string "Python", five copies of the string "Java" followed by four copies of the string "C++" so that your vector is now filled to сараcity. Add a class method named printArrayList to print out all the elements stored within an ArrayList on separate lines. Test your method to be sure it works a) Add a class method named delete to remove all copies of a particular string object passed in as a parameter. The parameter key should be of type String. That is, b) private static void delete (ArrayList<String> myArrayList,Object key) Comment out your first print call, and now include a call to delete (myArrayList, "Java") to test your delete method Include a call to printArrayList following it to verify that only five string objects now remain. Add a value-returning class method named count that can be used to count the number of times that a particular string object passed in as a parameter occurs within an ArrayList. Include a call to count in main to test your method.

Answer 1

/* import package ArrayList and Collections */

import java.util.ArrayList;
import java.util.Collections;

public class TestArrayList {

private static void printArrayList(ArrayList<String> list) {
System.out.println("\nArrayList Contains: ");
for (int i = 0; i < list.size(); i++) {
System.out.println(list.get(i)); // print array list
}
}
  
private static void delete(ArrayList<String> myArrayList, Object key) {
  
myArrayList.removeAll(Collections.singleton(key)); // remove all occurence of given object
}

private static int count(ArrayList<String> myArrayList, String c) {
return Collections.frequency(myArrayList, c); // return frequency of given string in list
}
  
public static void main(String[] args) {
ArrayList<String> myArrayList = new ArrayList<>(10);//arraylist with capacity 10
myArrayList.add("Python");// on copy of python
for (int i = 0; i < 5; i++) {// five copy of java
myArrayList.add("Java");
}
for (int i = 0; i < 4; i++) { //4 copy of C++
myArrayList.add("C++");
}
printArrayList(myArrayList); //print method
delete(myArrayList, "Java"); // delete method
printArrayList(myArrayList);//print
System.out.println("ArrayList Count of C++ is: "+ count(myArrayList,"C++"));

// count method number of time string occur
}

     
}

/* OUTPUT */

ArrayList Contains: Python Java Java Java 558888 ArrayList Contains: Python C++ C++ C++ C++ ArrayList Count of C++ is: 4 BUILD SUCCESSFUL (total time: 0 seconds)

/* PLEASE UPVOTE */