11.1 What are object references?

A. Introduction Anything is possible if you can program... :) B. Watch (Slides) C. Try: 1) Do you know ArrayList class is implemented by an array? 2) Can you implement insert/remove for 2-D arrays?

A. Introduction Arrays are powerful but their sizes are fixed once declared. To overcome the inconvenience, array lists are introduced in Java. Array lists are implemented by arrays behind the scene but to end users, they are resizable. B. Watch ( Slides ) C. Try: E.7.11-E7.14 of Big Java Early Obejcts

A. Introduction Now you are well equipped with the skills to create an array of 300 students, - not only their height or weight, but ALL info of these students. You define what you'd like to include in class Students, and then create an array of 300 Student objects. Each object may have a student's name, birthday, height, weight, gpa... B. Watch ( slides ) C. Try 1) Use class Person below to create an array of x persons. Prompt a user to enter x as numbers of persons to create, then input name and age of each person to fill the array. public class Person { private String name; private int age; public Person(String aName, int anAge) { name = aName; age = anAge; } /* @return the String form of this person / public String toString() { return name + " " + age; } public void printPerson() { System.out.println(this); } public void setName(String newName) { name = newName; } public void setAge(int newAge) { age = newAge; } } 2) Split the array above into two or more age groups, create a new array for each age group. 3) Create a 2-D array of Person to store different age groups: <12 years old, 12-18 years old, >18 years old. Assume each age group will have a maximum of 5 people.