3 A.List of References: Essential Book: Introduction to Java
Programming Comprehensive Version, 8 th Edition, Y. Daniel Liang,
Prentice Hall, 2011. Recommended Book: Java How to Program, 10th
Edition, P. Deitel, H. Deitel, Prentice Hall, 2012. Java How to
Program Course Coordinator: Dr. Essam H. Houssein Signature
:()
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4 Weighting of Assessments: Final-Term Examination (90 Degree)
65% Mid-Term Examination (10 Degree)10 % Practical and Oral
Examination (Project) (20 Degree) 20% Other types of assessment
(Assignments) (5 Degree) 5% 100 %
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5
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6 1.6 The Java Language Specification, API, JDK, and IDE The
Java language specification is a technical definition of the
language that includes the syntax and semantics of the Java
programming language. The application program interface (API)
contains predefined classes and interfaces for developing Java
programs.
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7 Java Development Toolkit JDK consists of a set of separate
programs, each invoked from a command line, for developing and
testing Java programs. Besides JDK, you can use a Java development
tool (e.g., Net- Beans, Eclipse, and TextPad)software that provides
an integrated development environment (IDE)
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8 2.3 Reading Input from the Console Console input is not
directly supported in Java, but you can use the Scanner class to
create an object to read input from System.in, as follows: Scanner
input = new Scanner(System.in);
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9
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10 2.4 Identifiers As you see in Listing 2.3, ComputeAverage,
main, input, number1, number2, number3, and so on are the names of
things that appear in the program. Such names are called
identifiers. All identifiers must obey the following rules: 2.8.2
Numeric Literals A literal is a constant value that appears
directly in a program. For example, 34 and 0.305 are literals in
the following statements: int numberOfYears = 34;
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11 System.out.println( (int) 1.7 ) ; 2.13 Character Data Type
and Operations The character data type, char, is used to represent
a single character. A character literal is enclosed in single
quotation marks. Consider the following code: char letter = 'A';
char numChar = '4';
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12 2.15 The String Type The char type represents only one
character. To represent a string of characters, use the data type
called String. For example, the following code declares the message
to be a string with value Welcome to Java. String message =
"Welcome to Java";
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13 2.16.3 Proper Indentation and Spacing Indentation is used to
illustrate the structural relationships between a programs
components or statements. Java can read the program even if all of
the statements are in a straight line, but humans find it easier to
read and maintain code that is aligned properly. Indent each
subcomponent or statement at least two spaces more than the
construct within which it is nested. A single space should be added
on both sides of a binary operator, as shown in the following
statement:
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14 2.16.4 Block Styles A block is a group of statements
surrounded by braces. There are two popular styles, next-line style
and end-of-line style, as shown below.
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15 2.17 Programming Errors 2.17.1 Syntax Errors Errors that
occur during compilation are called syntax errors or compile
errors. 2.17.2 Runtime Errors Runtime errors are errors that cause
a program to terminate abnormally. 2.17.3 Logic Errors Logic errors
occur when a program does not perform the way it was intended to.
Errors of this kind occur for many different reasons. Logic errors
are called bugs. The process of finding and correcting errors is
called debugging.
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16 3.4.1 One-Way if Statements A one-way if statement executes
an action if and only if the condition is true. The syntax for a
one-way if statement is shown below: if (boolean-expression) {
statement(s); }
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17 3.6 Two-Way if Statements A one-way if statement takes an
action if the specified condition is true. If the condition is
false, nothing is done. But what if you want to take alternative
actions when the condition is false? You can use a two-way if
statement. The actions that a two-way if statement specifies differ
based on whether the condition is true or false. Here is the syntax
for a two-way if statement: if (boolean-expression) {
statement(s)-for-the-true-case; } else {
statement(s)-for-the-false-case; }
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18
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19 3.15 switch Statements The if statement in Listing 3.6,
ComputeTax.java, makes selections based on a single true or false
condition. There are four cases for computing taxes, which depend
on the value of status. To fully account for all the cases, nested
if statements were used. Overuse of nested if statements makes a
program difficult to read. Java provides a switch statement to
handle multiple conditions efficiently. You could write the
following switch statement to replace
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20 the nested if statement in Listing 3.6: switch (status) {
case 0: compute taxes for single filers; break; case 1: compute
taxes for married filing jointly; break; case 2: compute taxes for
married filing separately; break; case 3: compute taxes for head of
household; break; default: System.out.println("Errors: invalid
status"); System.exit(0); }
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21 4.2 The while Loop The syntax for the while loop is as
follows: while (loop-continuation-condition) { // Loop body
Statement(s); }
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22 4.3 The do-while Loop The do-while loop is a variation of
the while loop. Its syntax is given below: do { // Loop body;
Statement(s); } while (loop-continuation-condition);
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23 4.4 The for Loop In general, the syntax of a for loop is as
shown below: for (initial-action; loop-continuation-condition;
action-after-each-iteration) { // Loop body; Statement(s); }
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24 5.2 Defining a Method The syntax for defining a method is as
follows: modifier returnValueType methodName(list of parameters) {
// Method body; }
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25
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26
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27 5.3.1 Call Stacks
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28 5.3.1 Call Stacks
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29 5.8 Overloading Methods that is, two methods have the same
name but different parameter lists within one class. 5.9 The Scope
of Variables The scope of a variable is the part of the program
where the variable can be referenced. A variable defined inside a
method is referred to as a local variable.
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30
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31 5.12 Method Abstraction and Stepwise Refinement Method
abstraction is achieved by separating the use of a method from its
implementation. The client can use a method without knowing how it
is implemented. The details of the implementation are encapsulated
in the method and hidden from the client who invokes the method.
This is known as information hiding or encapsulation.
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32 double[] myList = new double[4]; // Creating Arrays double[]
myList; // Declaring Array Variables This statement declares an
array variable, myList, creates an array of ten elements of double
type, and assigns its reference to myList. The size of an array
cannot be changed after the array is created.
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33 6.5 Copying Arrays Often, in a program, you need to
duplicate an array or a part of an array. In such cases you could
attempt to use the assignment statement (=), as follows: list2 =
list1; Another approach is to use the arraycopy method in the
java.lang.System class to copy arrays instead of using a loop. The
syntax for arraycopy is shown below: arraycopy (sourceArray,
src_pos, targetArray, tar_pos, length);
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34
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35 What is the difference between pass-by-value and
pass-by-sharing? public class Test { public static void
main(String[] args) { int x = 1; // x represents an int value int[]
y = new int[10]; // y represents an array of int values m(x, y); //
Invoke m with arguments x and y System.out.println("x is " + x);
System.out.println("y[0] is " + y[0]); } public static void {
number = 1001; // Assign a new value to number numbers[0] = 5555;
// Assign a new value to numbers[0] }
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36 6.9 Searching Arrays 6.10 Sorting Arrays 6.11 The Arrays
Class The java.util.Arrays class contains various static methods
for sorting and searching arrays, comparing arrays, and filling
array elements. These methods are overloaded for all primitive
types. double[] numbers = {6.0, 4.4, 1.9, 2.9, 3.4, 3.5};
java.util.Arrays. sort (numbers); // Sort the whole array
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37 char[] chars = {'a', 'c', 'g', 'x', 'y', 'z'};
System.out.println("(3) Index is " +
java.util.Arrays.binarySearch(chars, 'a')); System.out.println("(4)
Index is " + java.util.Arrays.binarySearch(chars, 't'));
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38 int[][] matrix; matrix = new int[5][5]; matrix[2][1] =
7;
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39 Assignment (1): Write a program that: 1- Displaying Prime
Numbers Page 137 2- Determining Leap YearPage 90 3- Displaying
CalendarsPage 151 4- Displaying Twin PrimesPage 195 5- Counting the
Occurrence of each Letterpage 212 6- Counting of Occurrence of
NumbersPage 227
