Semester Review

Chapters 1-7

Chapters from the text

•          Chapter 1 Introduction

•          Chapter 2 Java Applications (omit section 2.9)

•          Chapter 3 Classes and Objects (omit sections 3.9 & 3.10)

•          Chapter 4 Control Statements (omit sections 4.14 & 4.15)

•          Chapter 5 Control Statements (omit sections 5.10 & 5.11)

•          Chapter 6 Methods (omit sections 6.13 & 6.14)

•          Chapter 7 Arrays (omit sections 7.13 & 7.14)

•          Be sure to read the Wrap-Up at the end each chapter

Primitive types in Java

•          Integers

–          int and long

•          Floating points

–          float and double

•          boolean—either true or false

•          character

Classes and Objects

•          Every class is also a type

•          It is template that shows what objects of that type will be

•          A class encapsulates the data members of a type together with the methods that manipulate the object

•          An object is one instance of the class

Declaring variables

–          Java stores primitives differently than objects

•          The value of a primitive itself is stored in the variable location

•          All objects store the address where they can be found, not the object itself

•          This address is called a reference variable

•          All objects are stored in dynamic memory

–          The operating system sets aside space in dynamic RAM when requested by the executing program

–          The request for space is made by the keyword new

I/O

•          We used the Scanner class for input; it has several methods that can be called depending on the type of input the program is expecting

•          For output, we used .printf( ), print( ), and println( ), preceeded by System.out

•          printf( ) gives you more control over the formatting of output

•          The concatenation sysbol “+” can be used with print( ) or println( )

Memory Concepts

•          The executable program and space for the data it declares is stored in static RAM (the stack)

•          As the program runs, declaring an object requires calling a constructor.

            This call to a constructor asks the operating system for space in dynamic RAM (the heap) to store the object.

            It returns the address of the space allocated.

Control structures

•    Order of execution of a program is controlled by if/else statements and loops

            Selection & repetition statements

•    while loops and for loops

            All loops must have

•    An statement initialize a control variable

•    A statement to terminate the loop

•    A statement to change the control variable so the loop terminates

            A for loop does all three of these things in the for parentheses

            The programer must do all three separately with a while loop

Operators

•    Arithmetic operators

•    Relational operators

      = = != < > <= >=

•    Logical operators

      And or not

Methods

•    Every method must have

      A return type

      A method name

      Parentheses for arguments

•    A method may also have

      An access specifier (public or private)

      The keyword static

•    The method call transfers information to the method, and receives information back from the method

Arrays

•    An array is a data structure that holds a collection of related data of one type

•    The individual elements of an array are named using the array name and a subscript in [ ]

•    The subscript must be an integer, or an int variable

•    Arrays are processed using for loops

Strings

•    The most important thing to remember about Strings is that you cannot compare them with = =

•    You must use dot equals

•    If you want not equals, you use

 !(obj1.equals(obj2))