AP Computer Science --- Haas --- ArrayListGroceryList

Objective: Use the ArrayList class

Run the following example in BlueJ, make sure you understand how it works!

import java.util.*;
/**
 * Use ArrayList class to Implement GroceryList
 */
public class GroceryList {
 
  private ArrayList< String > groceries;

  public GroceryList() {
    groceries = new ArrayList();
  }
  
  /**
   * <<< size >>> returns the number of elements in the list
   */
  public int numberOfItems() {
    return groceries.size();
  }
  
  /**
   * <<< add >>> add an item to the end of the list and always returns true
   */
  public boolean addItem(String item) {
      return groceries.add(item);
  }
  
  /**
   * <<< add >>> inserts an item to the list at position specified 
   */
  public void addItem(int index, String item) {
      groceries.add(index, item);
  }
   
  /**
   * <<< get >>> returns the element at the specified index
   */
  public String getItem(int index) {
      return groceries.get(index);
  }
  
  /**
   * <<< set >>> replaces item at index with specified element
   * returns replaced element
   */
  public String setItem(int index, String item) {
    return groceries.set(index,item);
  } 
  
  /**
   * remove item at specified index
   */
  public String removeItem(int index) {
      return groceries.remove(index);
  }
  
  /** 
   * returns list of items 
   */
  public String toString() {
    String s = "";
    for (int i = 0; i < groceries.size(); i++) {
      s += groceries.get(i) + " ";
    }
    if (groceries.size() == 0) {
        s = "<<< no groceries on the list >>>";
    }
    return s;
  }

}   

public class ListTester {

  public static void main(String[] args) {
   
    //Create a new grocery list
    GroceryList myList = new GroceryList();

    //Print out the list
    System.out.println("Grocery list: " + myList);
    
    //Add some items
    myList.addItem("eggs");
    myList.addItem("bacon");
    myList.addItem("coffee");
     
    //Print out the list
    System.out.println("Grocery list: " + myList);
     
    //Print number of items in list
    System.out.println("Number of items: " + myList.numberOfItems());
 		
	//Add some items at various positions
    myList.addItem(1,"pickles");
    myList.addItem(2,"chips");
    
    //Print out the list
    System.out.println("Grocery list: " + myList);
    
    // get item at position 3
    System.out.println(myList.getItem(3));
    
    // replace item at position 3
    System.out.println(myList.setItem(3,"meat"));
    
    //Print out the list
    System.out.println("Grocery list: " + myList);

    // remove item 0
    System.out.println(myList.removeItem(0));

    //Print out the list
    System.out.println("Grocery list: " + myList);
  }
}