Defining Classes and Methods

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Ernest Singleton
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1 Defining Classes and Methods Week 09 Review Week09 Review Slide # 1

2 Agenda How to use Breakpoints How to compile classes on separate files Chapters 1-5 & 7 Review In-Class Lab exercise No Homework due!! Week09 Review Slide # 2

current line (the line the cursor is in) 2.

3 Setting Breakpoints There are two ways to set a breakpoint: 1. Select Set/Clear Breakpoint from the Tools menu of the Editor This will set a breakpoint in the current line (the line the cursor is in) 2. Click in the tag bar (the area left of the source lines where break points are displayed) Clicking in that area will set a breakpoint at the selected position. Week09 Review Slide # 3

Removing Breakpoints Two ways to clear a breakpoint: 1. Select Set/Clear Breakpoint from the Tools menu. This will clear the breakpoint in the current line (the line the cursor is in).

4 Removing Breakpoints Two ways to clear a breakpoint: 1. Select Set/Clear Breakpoint from the Tools menu. This will clear the breakpoint in the current line (the line the cursor is in). If there is no breakpoint in the current line, a breakpoint will be set. 2. Click directly onto the breakpoint displayed in the tag bar (the area left of the source lines where break points are displayed). This will remove the breakpoint. Week09 Review Slide # 4

5 Compiling Separate Files A class code is usually created on a separate file Exercise: 1. Create a class Dog and copy Listing 5.1 into that class. 2. Create another class DogDemo and copy listing 5.2 into it 3. Compile each of the classes separately. 4. Notice the connections between the two classes 5. Now run the main() method and follow them steps-bystep using the debugger Week09 Review Slide # 5

6 Times & dates: Exam 2 Directions Tuesday class: Tuesday, October 29, and maybe Thursday October 31 st Wednesday class; Wednesday, October 30th Chapters covered 1, 2, 3, 4, 5, & 7 Not an open book Cheat Sheets ( 1per chapter) You can use scratch sheets Your name MUST be on top of all the sheets you are using No laptops allowed Might cover tracing, programming project, and/or multiplechoice Week09 Review Slide # 6

7 Chapter 2 Review You need to know: How to declare and name variables of any data type How and where to define constants How to import libraries How to display messages on the console How to get input from the user and store it in an appropriate location How to initialize variables during declaration The difference between assignment (=) and equal(==) operators and where to use each of them Identifiers naming conventions Reserved words should NOT be used as variable names!!! Assignment compatibility & type casting rules Week09 Review Slide # 7

8 Chapter 2 Review (Cntd.) You need to know: Arithmetic operators (Unary, Binary, Ternary) Operator precedence rules Using parentheses to override precedence Shorthand representation of assignment operators +=, -=, *=, /=. %= Prefix & postfix increment & decrement operators ++, -- How to concatenate strings Escape characters \, \, \\, \n, \t, \b, \r, \f Formatting output / Format specifiers %c, %d, %f, %e, %s Scanner class methods next(), nextline(), nextint(), nextdouble(),.. Using comments Week09 Review Slide # 8

9 Chapter 3 Review Flowcharts symbols & usages If statements syntax If-then If-then-else Switch Convert from one form to another Compound statements Nested statements Common loop errors Boolean expressions Boolean operators Short-circuit evaluations Truth tables Week09 Review Slide # 9

10 Chapter 4 Review Pseudocode Loops While Do-While For Loop condition Loop control variable, counter, sentinel Loop body Nested loops Convert from one form of a loop to another Loops problems: Infinite loops Off-by-one loops When to use each type of loop Tracing loops Week09 Review Slide # 10

11 Chapter 5 Review Methods Void Returns a value (data type + return statement) Classes Objects / instances Syntax of declaring methods / classes Header Body Invoking methods Void Returns a value Arguments/parameters Formal Actual Argument lists Scope of parameters & local variables Overloaded methods Week09 Review Slide # 11

12 Chapter 7 Review Array declaration Array dimensions 1D, 2D,..., nd Indexes / subscripts Array length instance variable Base type Declaring arrays Initializing arrays Processing arrays using loops Array problems Out of bound error Partially filled arrays Passing arrays as arguments to methods Returning arrays as a result of calling a method Week09 Review Slide # 12

13 Chapter 7 Review (Cntd.) Possible array operations Search for an element in an array Sort array elements Insert an elements at a specific position Delete an element Sum elements Get average values of elements Printing elements Find largest or smallest value Check elements that satisfy a criteria Odd, even, divisible by a specific number,... Week09 Review Slide # 13

Chapter 2: Elements of Java

Chapter 2: Elements of Java Basic components of a Java program Primitive data types Arithmetic expressions Type casting. The String type (introduction) Basic I/O statements Importing packages. 1 Introduction