Exercise p12 #2a,b and #4



Classes

Definition: A single unit that defines both data

that will be used and the operations that can be

performed on the data.

methods are the operations (procedures and/or functions)

object is an instance of the class

examples chromosome/gene map => you

blueprint for a house => your house

Program Translation

Machine Language is the code boiled down to the 0’s and 1’s.

Other High Level Languages: Java:

Source Code Source Code

| |

Interpreter/ Compiler Compiler

| |

Object Code Byte Code Format

| (Machine Code not

Linker geared to a specific

| processor)

Executable (.exe file) |

Java Virtual Machine

(Interpreter… Machine

specific details done here)

|

Program Execution

Java Translation Process (Same as above)

Java Java Java Java Machine

Source( Compiler ( Byte ( Virtual ( Code

Code Codes Machine

(file.java) (file.class) (interpreter)

java file

Identifiers(variable names):

• can contain letters, digits, underscores and dollar signs

• first character cannot be a digit

• cannot contain blanks

• cannot be a keyword (p26 Table 1.2… below)

• unlimited number of characters but sticking to maximum lengths of 14 to 20 is better.

• use mnemonics – words used as a memory aid

Java Reserved Words (from page 26 Table 1.2)

abstract default if private this

boolean do implements protected throw

break double import public throws

byte else instanceof return transient

case extends int short try

catch final interface static void

char finally long strictfp volatile

class float native super while

const for new switch synchronized

continue goto package

Exercise p19 #1 (or “Name Game” quia activity)

General Information

Primitive Data types: int, char, float, double

Java is very case sensitive.

Single statements must end in a semicolon ( ; ).

Each program must have at least one class.

Example:

public class HelloWorld

{

public static void main (String [] args)

{

System.out.println (“Hello World”);

}

}

Assignment 1: Create the above “Hello World” application

Comments

// - single line comment

/*

*/ - Multi-line comment

/**

*/ - Multi-line documentation style comment

Dialog Boxes

import javax.swing.*

JOptionPane.ShowMessageDialog(null, “Hello World”, “Message”, JOptionPane.QUESTION_MESSAGE);

//different types of messages shown on page 37

modal – user must respond and close before program continues

modeless – application continues

Two types of methods

1. strict methods – must be used with objects

general form: objectName.methodName(arguments);

2. static methods - do not operate on an object

- receives all data as arguments

- if declared in a public class, can be used

outside of it’s own class.

- general-purpose; utility methods

View the First Book of Java Chapter 1 Powerpoint

Assignment 2: Create a program to input two decimal numbers and calculates the average and outputs the answer. You must use dialog boxes.

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