chapter 3© copyright janson industries 20141 ▮ explain difference between: ▮...

Chapter 3 © copyright Janson Industries 2014 1

▮ Explain difference between:

▮ Applications/Applets/Servlets

▮ AWT/Swing/SWT

▮ Inheritance

▮ Basic AWT visual components

▮ UML (Unified Modeling Language)

GUI Java

Non-graded assg part 1 part2


▮ Apps are stored & executed on the client PC

▮ Applets are “called” by a web page. The applet’s Java code▮ Stored on the server▮ Downloaded to the client PC▮ Run by the client browser

▮ Servlets are stored and run on the server▮ Servlets generate HTML that is sent to the

client’s browser

Apps/Applets/Servlets



Stored on client

Run on client

Stored on server

Run on server

Apps X X

Applets X X

Servlets X X



Stored on Run on

Apps client client

Applets server client

Servlets server server


▮ Client based apps Adv:

▮ Fast: execute on client, no communication lag

▮ No catastrophic failure

▮ Client based apps DisAdv:

▮ Must install app on each client computer▮

▮ Multiple copies of app:▮ Take up more space▮ Updating app more difficult/time consuming

Client Apps


▮ Server based apps Adv:

▮ Accessible from any computer with a browser

▮ One copy of app▮ Takes up little space▮ Updates to app are fast

▮ Server based apps DisAdv:

▮ Catastrophic failure – server goes out, no processing can occur

▮ Communication time lag – especially with applets

▮ Must download entire application before executing

Server Apps


▮ Many sets of GUI components:▮ AWT (Advanced Windowing Toolkit)▮ Swing▮ SWT (Simple Widget Toolkit)

▮ AWT implements each H/W platform’s version of the GUI components

▮ Swing is consistent across all H/W (but takes longer to “paint” the GUI)

Java GUI Components


▮ As much as possible, SWT implements each H/W’s platforms version of the GUI components

▮ Provides the added Swing components and functions

▮ Works differently than AWT and Swing

GUI Java


▮ AWT and Swing have similar sets of GUI components stored in packages (that are part of the JDK):▮ Frame - JFrame▮ Button - JButton▮ TextField - JTextField▮ Label - JLabel

▮ To use the GUI components, must “import” the AWT or Swing classes into your class

GUI Java


GUI Java

FRAME JFRAME


Using GUI Components

▮ AWT GUI classes in java.awt package

▮ You can use them by fully specifying their location▮ java.awt.Label empName = new

java.awt.Label();

▮ Or, use the import statement to identify the java.awt package▮ import tells complier to look in that location

for any non-fully specified classes▮ Sorta like the path and classpath but for the

compiler not JVM or Windows


GUI Components

// GUIEx.java

import java.awt.*;

public class GUIEx extends Frame { : : : : : :

Using import allows easier access to the GUI components because you

don’t have to fully specify the location of the GUI component

We define this class as a Frame with the extends “clause” in the class header

This make GUIEx a subclass of Frame


Subclass/Superclass

▮ Subclasses inherit all methods and variables of the superclass (also called Specialization)

▮ You can create superclasses to hold common information and functions

▮ For instance:▮ A Person superclass with name, address,

and phone number variables▮ Subclasses Employee, Customer, and

Supplier would all get these variables


Subclass/Superclass

▮ Subclasses inherit all methods and variables of the superclass (aka Specialization)

PersonString name, addr, phnum;

Supplier extends PersonString SuppNum;name = "Pat";addr="3 3rd St";phnum="333-3333";

Customer extends PersonString CustNum;name = "Mary";addr="2 2nd St";phnum="222-2222";

Employee extends PersonString EmpNum;name = "Joe";addr="1 1st St";phnum="111-1111";


Create a new class (Cust2) – File, New, Class

Click Browse...


Start typing “Frame”, select Frame, (and make sure its from the java.awt package), click OK then Finish


RAD creates a bare minimum class


Labels

▮ Display constant text on a frame

▮ Must define a label object and, optionally, set it’s text property

Label custNameLabel = new Label(“Joe Customer");


But you get an error

Click light bulb icon to get possible solutions


Click a solution to show the solution code

Double click solution to insert code

RAD will list solutions with most likely at top


What happens if you click the Run button and why?


When running, RAD first suggests saving changes

It’s usually a good idea: click OK


Gotcha: if you click the Run button, RAD will run Cust1

(the last application that was run)


Can display the Run drop down menu

Notice Cust1 is the first listed Run Configuration

This means it is the default application to be run

Can click Run Configurations...


Specify Cust2

Click Run

What’s going to happen and why?


Oops, forgot to create a main method that instantiates (creates) a Cust2 object


Getting Cust2 to work

▮ Since Cust2 will be instantiated you need

▮ A constructor for the class (i.e. must have method called Cust2)

▮ In addition, to get the frame and labels to work you must set their properties:

▮ Define sizes for the frame and labels

▮ Position the labels on the frame

▮ Make the frame visible


Frames

▮ In the constructor, specify:

this.setSize(600, 400);

this.setLayout(null);

(this refers to “this object”, i.e. the Cust2 frame)

▮ Layout null tells the system not to use the predefined BorderLayout▮ You will position the components

individually


Labels

▮ In constructor, set label size & location:

▮ labelVariableName.setSize(length, height)

▮ labelVariableName.setLocation(from left, from top)

▮ Numbers are in pixels

▮ Example (after the label object is created and after this.setLayout(null);) add:

▮ custNameLabel.setSize(100,10);

▮ custNameLabel.setLocation(155,135);


Labels

▮ In the constructor, after the label properties are set, add the label to the frame object (referred to as this)

▮ this.add(custNameLabel);

▮ At the end of the constructor, make the frame visible

▮ this.setVisible(true);


main method

▮ In the main method, must create a Cust2 object

▮ We will assign it to a variable called custTest

▮ Cust2 custTest = new Cust2();▮ (Actually, don't need to create variable and assign object

because we will not reference the Cust2 object)

▮ Time to run!


Display Run menu – notice Cust2 is default launch

Click Cust2 to run


Results in Cust2 object being created (instantiated)


▮ 1. Create a class as a subclass of Frame

▮ 2. Set the following Frame properties:▮ Layout to null▮ Size▮ Location (optional)▮ Visible to true

▮ 3. To view the frame, create an instance of the Frame subclass

Steps to Create and Display a Working Frame


How to Create a Working Label

▮ 1. Import the Label class

▮ 2. Create a Label object

▮ 3. Set the following label properties:▮ Size▮ Location▮ Text (optional)

▮ 4. Add the label to the frame


Cust2 (or any Frame subclass) does not inherit a close function from

Frame

To close the frame, click the Terminate button in the Console pane tool bar

import java.awt.Frame;

import java.awt.Label;

public class Cust2 extends Frame {

Label custNameLabel = new Label("Joe Customer");

Label custAddressLabel = new Label("123 Main St.");

Label custCSZLabel = new Label("Jax, FL 32246");

public Cust2(){

this.setSize(600, 400);

this.setLayout(null);

custNameLabel.setSize(100,10);

custNameLabel.setLocation(155,135);

this.add(custNameLabel);

custAddressLabel.setSize(100,10);

custAddressLabel.setLocation(155,155);

this.add(custAddressLabel);

custCSZLabel.setSize(100,10);

custCSZLabel.setLocation(155,175);

this.add(custCSZLabel);

this.setVisible(true);

}

public static void main(String[] args){

Cust2 custTest = new Cust2();

}

}


Non Graded Assg – Part 1

▮ Create Cust2 so it displays the same info as Customer but in a frame with 3 labels


Instead of displaying static info, we can pass the frame info to display

Like Cust1 did


Passing Info

▮ Need to change the frame's constructor to:

▮ Accept info

▮ Set the label value to the passed info


Passing Info

Constructor must accept

infoConstructor must set label value

Info must be passed


Passing Info

Problem: if 7 pieces of info need to be passed,

How easy is it to remember what’s the order?When is phone # passed: First? Second?

Sixth?Solution: object properties

If 2 pieces of info need to be passed,public Cust3(String name, String address){…


Properties

▮ Already worked with properties ▮ Label text and location, Frame size and layout

▮ In a class, each property is:

▮ Defined as a private class variable

▮ Has a getter method that returns the property value

▮ Has a setter method (usually with validation functions) that sets the value of the property


Properties

▮ Usually you will create an object

▮ Then manipulate the object properties▮ We created a label, then set its size, location,

text

▮ For instance:

▮ We’ll redefine the Customer class to have properties that hold the following info:

▮ Contact Person, Customer Name, Phone Number, Ship to Address


Creating Properties

▮ Define private variables for each property


Let RAD create the getters and setters

Click Source then Generate Getters and Setters...


Properties

▮ Select getters and setters or click Select All

▮ Can specify▮ Where methods should

be in the class▮ How they are grouped

▮ Click OK button

▮ Generates 14 methods


Can't fit all getters/setters in work areaCan see them all in the outline


Using Properties

▮ Just as you set Frame and Label object properties, a Customer object’s properties can now be set

▮ Then pass the Customer variable (assigned to the Customer object) instead of individual variables/values

▮ We will modify the customer application so that a Customer variable is passed to a Customer Frame


Using Properties

▮ A new class CustApp will be used to "kick off the application"

▮ This means CustApp will:

▮ Create a Customer object and assign it to a Customer variable

▮ Set the Customer object's properties

▮ Create a Customer Frame object and pass it the Customer variable (instead of individual variables/values)


New Customer Example

CustomerObject

CustFrameObject

1CustApp creates a Customer object, assigns to variable c, sets object’s properties

2CustApp creates a CustFrame object, assigns to variable

cf, and sends Customer variable

c

3CustFrame retrieves &

displays Customer object properties

CustApp


New Customer Example

CustomerObject

CustFrameObject

1

2CustApp creates a CustFrame object, assigns to variable

cf, and sends Customer variable

c

3

CustApp

Data Data


Using Properties

▮ Create a new Frame subclass CustFrame▮ CustFrame constructor accepts a variable of

type Customer and assigns it to a variable named cust

▮ CustFrame has four labels▮ custName▮ shipToLbl1▮ shipToLbl2▮ contactInfo

▮ CustFrame retrieves info from the Customer object and puts the info into the labels


Select project (JavaCourse) then File, New, Class

Specify name of Class and superclass


Need to define a constructor to accept a Customer

variable

Initial code

Cust Frame


public class CustFrame extends Frame {

}


Programming Technique

▮ We will code portions of the class, then test each portion as it is created

▮ Incremental coding makes finding errors easier

▮ If a new method is added and RAD shows an error, it has something to do with the new code

▮ If all the methods coded at once results in 42 errors, harder to determine what the errors are


Don’t forget, for frame to work need to:

Size the frame : this.setSize(300, 282); Set layout to null: this.setLayout(null);

Set visible: this.setVisible(true);


public class CustFrame extends Frame {

public CustFrame(Customer cust) {

}

}

Cust Frame

Even though CustApp passes a variable called c, CustFrame stores it in a variable

named cust


▮ Import the Label class: import java.awt.Label;

▮ Create 4 label objects and assign to variables

▮ Size and position the labels

Label custNameLbl = new Label();

Label shipToLbl1 = new Label();

Label shipToLbl2 = new Label();

Label contactInfo = new Label();

Cust Frame Labels

custNameLbl.setBounds(62, 65, 176, 23);

shipToLbl1.setBounds(62, 120, 176, 23);

shipToLbl2.setBounds(62, 175, 176, 23);

contactInfo.setBounds(62, 230, 176, 23);


▮ Set some test text

▮ Add the labels to the frame

▮ Test it : what do we need?

this.add(custNameLbl);

this.add(shipToLbl1);

this.add(shipToLbl2);

this.add(contactInfo);

Cust Frame Labels

custNameLbl.setText("test text");

shipToLbl1.setText("test text");

shipToLbl2.setText("test text");

contactInfo.setText("test text");

public static void main(String[] args) {

Customer c = new Customer();

CustFrame cf = new CustFrame(c);

}

▮ Code a main method in CustFrame to create a CustFrame object (to test so far)


CustFrame Labels

▮ In class assg: Try it!


▮ Need code to retrieve data from Customer object and put into labels

▮ Use Customer object getter to retrieve a property value

▮ Could do like this

Cust Frame Labels

String tempName = cust.getCustName();

custNameLbl.setText(tempName);

String tempStreet = cust.getShipToStreet();

shipToLbl1.setText(tempStreet);


▮ More efficient to do like this

▮ Two less statements no temp variables

▮ These labels are easy: one getter retrieves one label’s text

▮ Need to use concatenation for other label’s text▮ I.e. multiple getter return values go into these

labels

Cust Frame Labels

custNameLbl.setText(cust.getCustName());

shipToLbl1.setText(cust.getShipToStreet());


Concatenation

▮ Combines 2 strings into one▮ String a = new String(“Sam”);▮ String b = new String(“I am”);▮ a + b would be equal to “SamI am”

▮ Use concatenation (+) to combine multiple property values into one label shipToLbl2.setText(cust.getShipToCity() + ", " +

cust.getShipToState() + " " + cust.getShipToZip());

contactInfo.setText(cust.getContactPerson() + " Ph: " + cust.getContactPhone());


Customer

▮ So we’ve:▮ Added properties to Customer▮ Created CustFrame to display the properties

▮ Need to create a CustApp that▮ Creates a Customer object, a Customer variable

named c, and assigns the object to c▮ Sets values for the Customer properties▮ Creates a CustFrame object and passes the

Customer variable c, creates a CustFrame variable named cf, assigns the CustFrame object to cf


CustApp

▮ Create a class called CustApp▮ In CustApp

▮ Create a main method

▮ In main, write code to:▮ Create a Customer object, assign to variable c▮ Use setters to assign the following values in

the Customer object associated with variable c:▮ Kindness Foods, 1 Milkof St., Human, ME 03234▮ Joe Samaritan, 555-3333

▮ Create a CustFrame object and pass c, assign the CustFrame object to a variable named cf


Have RAD generate the main method


import java.awt.Label;import java.awt.Frame;import java.awt.Label;

public class CustFrame extends Frame {Label custNameLbl = new Label();Label shipToLbl1 = new Label();Label shipToLbl2 = new Label();Label contactInfo = new Label();

public CustFrame(Customer cust) { this.setSize(300, 282);this.setLayout(null); this.setVisible(true);custNameLbl.setBounds(62, 65, 176, 23);shipToLbl1.setBounds(62, 120, 176, 23);shipToLbl2.setBounds(62, 175, 176, 23);contactInfo.setBounds(62, 230, 176, 23);custNameLbl.setText(cust.getCustName());shipToLbl1.setText(cust.getShipToStreet());shipToLbl2.setText(cust.getShipToCity() + ", " + cust.getShipToState() + " " + cust.getShipToZip());contactInfo.setText(cust.getContactPerson() + " Ph: " + cust.getContactPhone());this.add(custNameLbl);this.add(shipToLbl1);this.add(shipToLbl2);this.add(contactInfo);}

public static void main(String[] args) { Customer c = new Customer(); CustFrame cf = new CustFrame(c); }

}

public class CustApp {

public static void main(String[] args) {

Customer c = new Customer();

c.setContactPerson("Joe Samaritan");

c.setContactPhone("555-3333");

c.setCustName("Kindness Foods");

c.setShipToStreet("1 Milkof St.");

c.setShipToCity("Human");

c.setShipToState("ME");

c.setShipToZip("03234");

CustFrame cf = new CustFrame(c);

}

}


Non-graded assg: Finish creating the Customer Application

When run should look like


Non-graded Assg

▮ Export as one jar file▮ Cust2.java

▮ Customer.java

▮ CustFrame.java

▮ CustApp.java

▮ Email the jar file as an email attachment to [email protected]


UML

▮ Unified Modeling Language

▮ Diagrams to show class methods and variables and interclass relationships:

▮ Composition

▮ Specialization


Class Diagram Example

▮ For each class a box is created

▮ The box consists of three areas:

▮ Identification (name)

▮ Attributes (variables)

▮ Operations (methods)

▮ Attributes and Operations are further identified as public or private (+,-)

Customer

- name:String- address:String

+ setName:void+ setAddress:void



▮ Attribute entries also specify the attribute’s type (the type is preceded by a colon & follows the attribute name)

Customer

-name:String-address:String

+setName:void+setAddress:void

▮ Operation entries also specify a return value (the return value is preceded by a colon & follows the operation name)



▮ Attribute entries can also specify an initial value:

Attribute:Type=initial_value

name:String=“Joe Programmer”

▮ Operation entries can also specify the expected parameter(s) type(s):

Operation(parm_list):returned_value

getCustomerPO(int):String


UML Relationship Diagrams

▮ Can show specialization

Object

Applet

Component

TextComponentContainerButton

Panel TextField

Frame

Window


Click Finish


Initially shows class diagram for that class

As you add, will show composition relationship

Right click Customer and CustFrame

Choose

Visualize

Add to current diagram


Can't fit diagram in window

In outline view, click Overview button to display “the big picture”

Can drag boxes, close Palette, & resize window to fit


Initially only shows composition (use relationship)


Need to simplify diagram

Select all three boxes (Ctrl+click)

Right click one box and choose:

Filters

Show/Hide Compartment

Name Compartment only


Want to see superclasses, must add to diagram

Expand JRE System Library, vm.jar, java.lang


Select Object.class and String.class

Right click either class and select Visualize then Add to Current Diagram


Close up vm.jar and expand rt.jar and java.awt


Scroll down and select Frame.class and Label.class

Right click either class and select Visualize then Add to Current Diagram


Right click anywhere on diagram background and choose Select then All Shapes


Right click Frame box and select Filters, Show/Hide Compartment, Name Compartment Only


Right click background and choose Arrange All


Still need to drag boxes into better arrangement and resize the boxes


You can modify which relationships are shown


New diagram file in the project


Other Resources

▮ JavaRanch: http://www.javaranch.com/▮ Forums, faqs, tutorials

▮ http://www.javaranch.com/campfire has stories/tutorials concerning various java topics

▮ Here is a link to some online java videos:▮ http://www.youtube.com/user/webhasher/

videos?sort=da&view=u

▮ I looked at several of them and they seemed pretty good

chapter 3© copyright janson industries 20141 ▮ explain difference between: ▮...

Documents

gui componentsawt gui

gui components guiex

gui componentsprovides

gui componentsswing

similar sets of gui

client based apps adv

apps disadv

server based apps adv