Create 15a Lists

Week 2: Methods, strings and lists/15a Lists

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+An example of a program that creates a list and stores five strings in it:
+
+import java.util.ArrayList;
+
+public class Example {
+    public static void main(String[] args) {
+
+        // ArrayList datatype
+        // each element: String datatype
+        // list name: names
+        // 'new' - initialise list object
+        ArrayList<String> names = new ArrayList<>();
+
+        names.add("Jack Java");
+        names.add("Paula Python");
+        names.add("Cinthia C");
+        names.add("Randy Rust");
+        names.add("Pia PHP");
+
+        System.out.println(names);
+    }
+}
+
+
+ 
+
+Program outputs:
+[Jack Java, Paula Python, Cinthia C, Randy Rust, Pia PHP]
+
+
+
+
+==============================================
+
+
+
+List type
+- List can store elements of various 'basic type'
+- BUT type SPECIFICATION - CANT USE 'basic type'
+- SPECIFICATION - need to use 'envelope class'
+
+Basic type |	Correspoding envelope class
+int	             Integer
+double	         Double
+char		     Character
+boolean		     Boolean
+float		     Float
+
+
+
+
+ArrayList<String> participants = new ArrayList<>();
+participants.add("Ann Attendee");
+
+ArrayList<Integer> results = new ArrayList<>();
+results.add(3);
+
+ArrayList<Character> chars = new ArrayList<>();
+chars.add('x');
+
+
+
+
+
+
+
+==============================================
+
+
+list elements
+
+
+
+
+add
+ArrayList<String> attendees = new ArrayList<>();
+attendees.add("Ann Attendee");
+System.out.println(attendees); //[Ann Attendee]
+
+
+attendees.add("Alex Attendee");
+attendees.add("Winry Winner");
+System.out.println(attendees); //[Ann Attendee, Alex Attendee, Winry Winner]
+
+
+Program outputs:
+[Ann Attendee]
+[Ann Attendee, Alex Attendee, Winry Winner]
+
+
+
+
+
+
+
+
+
+get
+ArrayList<String> attendees = new ArrayList<>();
+attendees.add("Ann Attendee");
+attendees.add("Alex Attendee");
+attendees.add("Winry Winner");
+
+System.out.println(attendees.get(0)); //Ann Attendee
+System.out.println(attendees.get(2)); //Winry Winner
+
+
+
+// create new empty list
+ArrayList<Integer> numbers = new ArrayList<>();
+// from i=1 to 10, populate list with the 'multiple of 10'
+for (int i=1; i<=10; i++) {
+    numbers.add(i * 10);
+}
+
+System.out.println(numbers);
+System.out.println(numbers.get(0) + ", " + numbers.get(1));
+System.out.println(numbers.get(9));
+
+
+
+Program outputs:
+Ann Attendee
+Winry Winner
+[10, 20, 30, 40, 50, 60, 70, 80, 90, 100]
+10, 20
+100
+
+
+
+
+
+
+
+
+
+
+
+
+add AT SPECIFIC IDX
+remove
+
+ArrayList<Double> results = new ArrayList<>();
+results.add(1.0);
+results.add(2.5);
+results.add(8.5);
+
+System.out.println(results); //[1.0, 2.5, 8.5]
+
+
+results.add(0, 9.9); // add to start
+System.out.println(results); //[9.9, 1.0, 2.5, 8.5]
+
+results.add(1, 10.0); // add to index 1
+System.out.println(results); //[9.9, 10.0, 1.0, 2.5, 8.5]
+
+results.remove(0);  // remove the first
+System.out.println(results); //[10.0, 1.0, 2.5, 8.5]
+
+results.remove(3); // remove from index 3
+System.out.println(results); //[10.0, 1.0, 2.5]
+
+Program outputs:
+[1.0, 2.5, 8.5]
+[9.9, 1.0, 2.5, 8.5]
+[9.9, 10.0, 1.0, 2.5, 8.5]
+[10.0, 1.0, 2.5, 8.5]
+[10.0, 1.0, 2.5]
+
+
+