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**WEEK 13** **The Graphics Class** - provides the framework for all graphics operations within the AWT - plays two different, but related, roles: §  sets the graphics context §  provides methods for drawing simple geometric shapes, text, and images to the graphics destination ·         Bec...

**WEEK 13** **The Graphics Class** - provides the framework for all graphics operations within the AWT - plays two different, but related, roles: §  sets the graphics context §  provides methods for drawing simple geometric shapes, text, and images to the graphics destination ·         Because the Graphics class is an abstract base class, it cannot be instantiated directly. ** ** **The paint()and repaint()Methods** - The paint () method is used to display text, shapes, and graphics within the applet window. -  The header for the paint() method is: o   public void paint(Graphics g) ·         You don't call the paint () method directly.  Instead, you call the repaint() method when a window needs to be updated, such as when it contains new images or you moved a new object onto the screen **The drawString()Method** ·         Allows you to draw a String in a JApplet window. ·         Requires three arguments: a String, an xaxis coordinate, and a y-axis coordinate. ·         A member of the Graphics class, thus you need to use a Graphics object to call it. **Using the setFont() Method** ·         The appearance of strings drawn using Graphics object can be modified using the setFont() method. ·         The setFont() method requires a Font object, which you create with a statement such as, o   Font font = new Font(\"Verdana\", Font.BOLD, 26); ·         Then, the Graphics object is instructed to use the font by using it as the argument in a setFont() method call. **Using the setColor() Method** ·         The Colorclass contains 13 constants. ·         These constants can be used as argument to the setColor() method.   Example: g.setColor(Color.BLUE);   ·         You can create your own Colorobject with the statement: Color myColor = new Color(r,g,b); Where r, g, and b are numbers representing the intensities of red, green, and blue in the desired color. ·         These three numbers can range from 0 to 255, with 0 being the darkest shade of the color and 255 being the lightest.    **Creating Graphics and Graphics2DObjects** ·         Supposed you want to display a string when the user clicks a JButton, you write the actionPerformed() method as follows: public void actionPerformed(ActionEvent e)  { Graphics g = getGraphics(); g.drawString(\"You pressed the button!\", 50, 100); } **WEEK 14** **Drawing Lines and Rectangles** ·         The drawLine() method is used to draw a straight line between any two points on the screen.  ·         This method takes the four arguments: x- and y-coordinates of the line's starting point and the x- and y-coordinates of the line's end. o   Example: §  line.drawLine(10, 10, 100, 200);   ·         The drawRect() method is used to draw the outline of a rectangle while the fillRect() method is used to draw a solid, or filled, rectangle. ·         Each of these methods requires four arguments:  o   The first two arguments represent the x- and y coordinates of the upper-left corner of the rectangle. o   The last two arguments represent the width and height of the rectangle. o   Example: §  drawRect(20, 100, 200, 10); ·         The clearRect() method also requires four arguments and draws a rectangle.   ·         The drawRoundRect() method creates rectangles with rounded corners. ·         This method requires six arguments:  o   The first four arguments match the four arguments required to draw a rectangle: the xand y-coordinates of the upper-left corner, the width, and the height. o   The two additional arguments represent the arc width and height associated with the rounded corners.   ·         The drawOval() is one of the methods of a Graphics object that draws a circle or an oval that fits within the rectangle specified by four arguments: x- and y-coordinates, width, and height. ·         The oval is drawn inside a rectangle whose upper-left hand corner is at (X, Y), and whose width and height are as specified. o   Example: §  g.drawRect(50, 50, 100, 60); g.drawOval(50, 50, 100, 60); **WEEK 15** **Drawing Arcs** ·         In Java, you can draw an arc using the Graphics drawArc() method. ·         The drawArc() method requires six arguments: o   The x-coordinate of the upper-left corner of an imaginary rectangle that represents the bounds of the imaginary oval that contains the arc o   The y-coordinate of the same point o   The width of the imaginary rectangle that represents the bounds of the imaginary oval that contains the arc o   The height of the same imaginary rectangle o   The beginning arc position o   The arc angle   ·         The fillArc() method creates a solid arc.  ·         This method is useful for drawing pie-shaped pieces of a circle or oval. o   Example: §  solidArc.fillArc(10, 50, 100, 100, 20, 320); solidArc.fillArc(200, 50, 100, 100, 340, 40); **WEEK 16** **Creating Polygons** ·         In Java, there are two approaches in drawing polygons: a method and a class. ·         The drawPolygon() method requires three arguments: two integer arrays and a single integer. Example: import javax.swing.\*; import java.awt.\*; public class DrawPolyDemo extends JApplet { public void paint(Graphics g) { int xPoints\[\] = {5, 25, 50, 30, 15, 5}; int yPoints\[\] = {10, 35, 20, 65, 40, 10 }; g.drawPolygon(xPoints, yPoints, xPoints.length); } }   ·         The second approach to drawing polygons is using the Polygon class to construct a Polygon object. ·         Once you have a Polygon object, you can simply pass it as a single argument to the fillPolygon() method. Example: Polygon poly = new Polygon(xPoints, yPoints, size); g.fillPolygon(poly); ·         You then use the addPoint() method in statements such as the following to add points to the polygon: o   poly.addPoint(100,100); o   poly.addPoint(150,200); o   poly.addPoint(50,250); ** ** **Copying an Area** ·         The copyArea() method is used to copy a rectangular area of a Graphics object into another area.  This method requires six parameters: o   The x- and y-coordinates of the upper-left corner of the area to be copied o   The width and height of the area to be copied o   The horizontal and vertical displacement of the destination of the copy Example: g.copyArea(0, 0, 20, 30, 100, 50); **WEEK 17** **Introduction** ·         The Java Database Connectivity (JDBC) API is the industry standard for database independent connectivity between the Java programming language and a wide range of databases. ·         The JDBC API provides a call-level API for SQL-based database access. **JDBC Architecture** ·         The JDBC API contains two major sets of interfaces: o   the JDBC API for application writers o   the lower-level JDBC driver API for driver writers **JDBC Architecture** ·         Direct-to-Database Pure Java Driver o   This style of driver converts JDBC calls into the vendor-specific database management system (DBMS) protocol so that client applications can communicate directly with the database server. ·         Pure Java Driver for Database Middleware o   This style of driver translates JDBC calls into the middleware vendor\'s protocol, which is then translated to a DBMS protocol by a middleware server. ** ** **JDBC Overview** ·         The JDBC API makes it possible to do three things: o   Establish a connection with a database or access any tabular data source o   Send SQL statements o   Process the results **Getting Started** ·         In order to create Java application that interacts with a database, you need to do the following: o   Install the Java platform, which includes the JDBC API. o   Install a driver. o   Install your DBMS if needed.   **Loading Drivers** ·         To manually load the database driver and register it with the DriverManager, load its class file. Class.forName(\) ·         For JDBC--ODBC Bridge driver, the following code will load it: Class.forName(\"sun.jdbc.odbc.JdbcOdbcD river\"); or new sun.jdbc.odbc.JdbcOdbcDriver();   **Making the Connection** ·         The second step is to create a Connection object. Connection con = DriverManager.getConnection( url, \"myLogin\", \"myPassword\"); Example String url = \"jdbc:odbc:adprog1\"; Connection con = DriverManager.getConnection(url, \"myLogin\", \"passwd\"); ·          Methods that you can use in creating a database connection: java.sql.DriverManager o   getConnection(String url, String user, String password) throws SQLException ·          java.sql.Connection o   Statement createStatement() throws SQLException void close() throws SQLException void setAutoCommit(boolean b) throws SQLException void commit() throws SQLException void rollback() throws SQLException   **Creating JDBC Statements** ·         A Statement object is what sends your SQL statement to the DBMS. ·         The Connection object instance is used to create the Statement object stmt: Statement stmt = con.createStatement(); ·         For a SELECT statement, the method to use is executeQuery. ·         For statements that create or modify tables, the method to use is executeUpdate.  Example Statement stmt = con.createStatement(); stmt.executeUpdate(\"INSERT INTO PRODUCTS \" + \"VALUES ('P00001\', 101, 7.99, 0, 0)\");   **Retrieving Values from Result Sets** ·          The JDBC API returns results in a ResultSet object. ResultSet rs = stmt.executeQuery(\"SELECT PROD\_NAME, PRICE FROM PRODUCTS\"); ** **