Unit 1: Introduction to Java

Syntax and Various Punctuation ...

• Java is CaseSensitive. "String" is not the same as "string".
• All lines end with ;
• ... unless the line begins a code block { } in which case it ends with { or }
• white space and <ENTER> do not matter, although it is good form to have only one line of code per line of text
• = means "is assigned to"
  == means "is equal to?"
• Types of brackets and separators:
  • { } defines blocks of code and automatically initializes arrays
  • ( ) are used for most other needs - e.g BEDMAS, passing parameters in functions, if, for, ...
    Encloses arguments in method definitions and calling; adjusts precedence in arithmetic expressions; surrounds cast types and delimits test expressions in flow control statements
  • [ ] are used for declaring arrays and accessing array elements
    
    
  • ; terminates statements
  • . Selects a field or method from an object; separates package names from sub-package and class names
  • , separates successive identifiers in variable declarations; chains statements in the test, expression of a for loop
  • : Used after loop labels
• Comments:
  • // this is a one-line comment
  • /* this comment is
    a multiline comment */
• Strings and printing: we'll look at these in detail later
  • Strings must be enclosed in " ". Single quotes ' ' are for characters, not strings.
    e.g. "fossil" vs "f" vs 'f' . The first two are strings. The third is a (single) character.
    Note: if you copy and paste from the internet or a document, make sure that your quotes are " " not “ ”.
  • This is the standard way to print text:

    System.out.print("Hello world");

  • If you want to add a new line at the end:

    System.out.println("Hello world");

  • Concatenating strings: use the + sign.

    System.out.println("Mark = " + finalMark);

• Escape characters:
  There are five common escape characters. Make sure that you know how to use them.
  
  1. \n (newline)
  2. \t (tab)
  3. \\ (backslash)
  4. \" (double quotes)
  5. \' (single quote) You don't need to use \' in strings. Just type '. It's only needed in a char variable.
  Each of these is one character,even though it takes two keystrokes to type.

Style: Naming and Indenting

You'll want to come back to this section later on in the course

• There are different ways to indent programs. See Wikipedia "indent style"
• This is my recommended way to name variable, functions and classes. Please follow it.
• Java Style Recommendations. Most of this is excellent. Read this, and if you even understand 1/4 it will be very helpful