Best Practice of Java Array Declaration

To declare a array in Java, you have following options:

1. dataType[] variableName;
2. dataType variableName[];
3. dataType []variableName;

The 1st is clearly related to how Java actually works, and you can read it as "dataType array variableName".

The conclusion is:

• dataType[] variableName;
• dataType[][]...[] arrayName;
  

IE8 user agent string

IE8 have 3 kinds of browser mode, but give different user agent string

IE7 mode give you Mozilla/4.0 (compatible; MSIE 7.0; ...;)
IE8 mode give you Mozilla/4.0 (compatible; MSIE 8.0; ...; Trident/4.0; ...;)
IE8 compat view mode give you Mozilla/4.0 (compatible; MSIE 7.0; ...; Trident/4.0; ...;)

Trident/4.0 is the important string to determine the real mode and version of IE8.

Java Operators

.         []           ()
++        --           !            ~
*          /           %
+         -
<<        >>           >>>         <<<
<         >            <=           >=
==        !=
&         |
^
&&
||
?:
=

Java Data Types

Primitive Data Types

• boolean (true, false)
  
• char (8 bits)
  
• byte (8 bits)
• short (16 bits)
• int (32 bits)
• long (64 bits)
• float (32 bits)
• double (64 bits)

Reference Variables vs. Primitive Variables

• Primitive variables are variables with primitive data types. They store data in the actual memory location of the variable is.
• Reference variables are variables that stores the address in the memory location. It points to another memory location of the actual data is.

My First Java Program

public class Hello {
    /**
     * My first Java program
     */
    public static void main(String[] args) {
        //prints the string "Hello world!" on screen
        System.out.println("Hello world!");
    }
}

Error Types

• Syntax errors
• Run-time errors

Java Comments

• C++ Style Comments
• C-Style Comments
• Special Javadoc Comments

About Java

What is Java Technology?

• A programming language
  
• A development environment
  
• An application environment
• A deployment environment

Some Features of Java

• The Java Virtual Machine (JVM)
  
• Garbage Collection
• Code Security