AP Computer Science --- Haas --- ArrayListNumbers

Objective: Use the ArrayList class with integers and doubles

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

import java.util.*;

public class ArrayListNumbers {

  public static void main(String args[]) {
      /**
       * ArrayLists can only hold objects 'int' is NOT an object 
       */
      ArrayList < Integer > myInt = new ArrayList< Integer >();

      /**
       * old version of java:  'wrap' numbers in Integer object 
       */
      Integer Int1 = new Integer(6);
      Integer Int2 = new Integer(8);
      myInt.add(Int1);
      myInt.add(Int2);
      
      /**
       * new version of java: 'autoboxing' 
       */
       myInt.add(10);
       myInt.add(12);
       
      /**
       * old version of java:  'unwrap' numbers using inValue 
       */
      for (int i = 0; i < myInt.size(); i++) {
        System.out.println(myInt.get(i).intValue());
      }

      System.out.println();

      /**
       * new version of java: 'autoboxing' 
       */
       for (int i = 0; i < myInt.size(); i++) {
         System.out.println(myInt.get(i));
       }
      

      /**
       * ArrayList example with double
       */  
      ArrayList < Double > myDoub = new ArrayList< Double >();
      myDoub.add(10.5);
      myDoub.add(6.2);
      myDoub.add(9.0);
      
      System.out.println();
      for (int i = 0; i < myDoub.size(); i++) {
        System.out.println(myDoub.get(i));
      }

  }
}