The document discusses the Java programming language and programming process. It explains that Java source code is compiled into bytecode, which is then interpreted by a Java Virtual Machine (JVM) and executed on any computer. It describes the structure of Java programs including classes, methods, and comments. The document also discusses the different types of errors that can occur including syntax errors detected by the compiler, runtime errors detected during execution, and logic errors that produce incorrect results.

1. EXPLAINING THE PROGRAMMING
PROCESS & TYPES OF ERRORS
Chapter 1.3:

2. The Java Programming Language
 Created by Sun Microsystems, Inc.
 introduced in 1995 and it's popularity has grown
quickly since
 Rich library
 Platform-independent ("write once, run anywhere")
or architecture-neutral

3. Java Translation
 The Java compiler translates Java source code
into a special representation called bytecode
 Java bytecode is not the machine language for
any traditional CPU
 Another Java software tool, called an interpreter
(or Java Virtual Machine (JVM)) , translates
bytecode into machine language and executes it

4. Java Translation
Java source
code (program)
Machine
code
Java
bytecode
Bytecode
interpreter
Java
compiler

5. Portability
 After compiling a Java program into byte-code,
that byte-code can be used on any computer with
a byte-code interpreter and without a need to
recompile.
 Byte-code can be sent over the Internet and used
anywhere in the world.
 This makes Java suitable for Internet applications.

6. Becoming Familiar with your
Computer to use Java
 Understand files and folders/directories
 Locate the Java compiler/ Install J2SE
 Set path & Java class path
 Write a simple program (later)
 Save your work
 Compile & run
 Use Dos Command Prompt or IDE

7. A DOS Command Window

8. An Integrated Development
Environment

9. File Hello.java
1 public class Hello
2 {
3 public static void main(String[] args)
4 {
5 // display a greeting in the console window
6 System.out.println("Hello, World!");
7 }
8 }

10. Java Program Elements
 A Java program is made up of class definitions.
 A class definition must contains a header and a
body.
 A class contains zero or more methods
 A method is a named section of code that also has
a header & body
 A method contains program statements
 Single-line (starts with //) and multi-line (enclosed
by /* and */) comments are used to document the
code

11. Java Program Structure
public class Hello
{
}
// comments about the class
class header
class body
//Comments can be placed almost anywhere

12. Java Program Structure
public class MyProgram
{
}
// comments about the class
public static void main (String[] args)
{
}
// comments about the method
method header
method body

13. Compiling and Running
 Type program into text editor
 Save (file name must be similar to class name)
 Open Dos Window
 Change directory to saved file directory
 Compile into byte codes
javac Hello.java
 Execute byte codes
java Hello

14. Processing a Java Program

15. Class Loader
 A Java program typically consists of several
pieces called classes.
 Each class may have a separate author and each
is compiled (translated into byte-code) separately.
 A class loader (called a linker in other
programming languages) automatically connects
the classes together and loads the compiled code
(bytecode) into main memory.

16. Creating a Java Program…
JVM
Create/modify source code
Source code
Compile source code
Byte code
Run byte code
Output
Syntax errors
Runtime errors or
incorrect results

17. Errors
 It is common for programmer to make mistake in a
program.
 Three kinds of errors
 Syntax errors
 Runtime errors
 Logic errors

18. Syntax Errors
 Grammatical mistakes in a program
 The grammatical rules for writing a program are very strict
 The compiler catches syntax errors and prints an
error message.
 Example: using a period where a program expects
a semicolon
 System.out.print("..."),
 System.out.print("Hello);

19. Runtime Errors
 Errors that are detected when your program is
running, but not during compilation
 When the computer detects an error, it terminates
the program and prints an error message.
 Example: attempting to divide by 0

20. Logic Errors
 Errors that are not detected during compilation or
while running, but which cause the program to
produce incorrect results
 Example: an attempt to calculate a Fahrenheit
temperature from a Celsius temperature by
multiplying by 9/5 and adding 23 instead of 32
 E.g
 System.out.print("Hell");