topics.txt

Java Beans
     either has a default constructor JavaBean() or Serializable
     matching methods: getX() and setX() both public

     public void setX(int x) { internalx = x; }
     public int getX() { return internalx ; }
     public int[] getY() { }
     public void setY(int y[]) {}

     you may have other methods, but the automated code does not know about that

**Reflection API

Comparison   equals
Identity     ==
2 ==2 that's different, 2 is not an object
Cloneable
String Optimization
StringBuffer
StringBuilder
	Immutable objects: String, Integer, Float, Double

**ArrayList<T> shallowcopy

wrapper classes
Float f = new Float(5.2f);
Double d = new Double(2.5);
Integer i = new Integer(3);

f = new Float(f.floatValue() + 1);
f = f + 1;

ArrayList<Double> a = new ArrayList<>();
for (int i = 0; i < 1000; i++)
  a.add(i); // autoboxing new Double(i)
a.set(50, 42.8); // set can only be used once the position exists.

//traversing the array list
for (int i = 0; i < a.length; i++)
  System.out.print(a.get(i));

for (Iterator<Double> i = a.iterator(); i.hasNext(); ) {
  Double d = i.next();
  System.out.print(d);
}

for (Double d : a) {
  System.out.print(d);
}

review problem:
1. Build an ArrayList of numbers from 1 to 10	1 2 3 4 5 6 7 8 9 10
2. Remove elements from the end until there are only 5    1 2 3 4 5
3. Now remove all odd numbers from the list   2 4
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16...
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16...
  i
j
HashMap<String, Double> quotes = new HashMap<>();
quotes.put("AAPL", 204);
quotes.put("OIL", -35);

double p = quotes.get("AAPL");

You should be able to dump out the entire hashmap but I won't ask that for the test

*** not on final, but learn before interview!!!
for (Map.Entry<String,Double> entry : quotes.entrySet()) {
  System.out.println(entry.getKey() + "==>" + entry.getValue());
}

test yourself (not so important for final, but VERY important for interview)
load symbols and price from disk, look up symbol.

*** LinkedList<Integer> a = new LinkedList();
a.insert(0, 5);






**Serializable
Write a method yourself to serialize to JSON.

class Quiz {
  String name;
  int points;
  int numQuestions;

  public void save(PrintWriter p) {
    p.println("{");
    p.println("\"" + 5); // "5
    p.println('"' + 5); // will print whatever character is 5 more than "
  }
}
/*
{
  "name": "Java Objects",
  "points": 10,
  "numQuestions": 20
}

**Thread	not on final! I forgot to do it before!

class MyThread extends Thread {
  @Override
  public void run() {

  }
}
  
Thread t = new Thread(); // nothing happens
t.start(); // run is executed


class, abstract class, interface, anonymous inner class, inner class, static inner class

this
super(); // first line of constructor calls parent
super("title"); // calls parent's constructor with a String parameter.

public void paint(Graphics g) {
  super.paint(g);
  ...
}



** not on final

try {
    PrintWriter pw = new PrintWriter(new BufferedWriter(new FileWriter("test.dat")));
    pw.println("hello");
    pw.close(); // be sure to close the file!!!
} catch (IOException e) {
  e.printStackTrace();
}

Scanner!


To add a listener to a JButton (or a JTextField)

JButton b = new JButton("ok");

JTextField tf = new JTextField();
tf.addActionListener( new ActionListener() {
  public void actionPerformed(ActionEvent e) {
    // do something!
  }

});