This document discusses Chapter 2 of an introduction to Java programming textbook. It covers elementary programming concepts such as writing simple Java programs to perform computations, using variables to store data, numeric data types, operators, and literals. The chapter objectives are to learn how to solve practical problems by working with Java primitive data types, variables, input/output, and other basic programming elements.
Java Inheritance with its type and basic examples
Reference
https://docs.oracle.com/javase/tutorial/java/IandI/subclasses.html
https://www.ebhor.com/java-inheritance/
Java Inheritance with its type and basic examples
Reference
https://docs.oracle.com/javase/tutorial/java/IandI/subclasses.html
https://www.ebhor.com/java-inheritance/
itft-Decision making and branching in javaAtul Sehdev
Decision Making Statements,The if Statement, SIMPLE IF STATEMENT, The If…else Statement, Nesting of IF..Else Statements, THE else if ladder, The Switch Statement, rules apply to a switch statement
Swing is a GUI widget toolkit for Java. It is part of Oracle's Java Foundation Classes (JFC) – an API for providing a graphical user interface (GUI) for Java programs.
In the Java programming language, the final keyword is used in several different contexts to define an entity that can only be assigned once. Once a final variable has been assigned, it always contains the same value.
Java abstract class & abstract methods,Abstract class in java
Abstract classes are classes that contain one or more abstract methods. An abstract method is a method that is declared, but contains no implementation. Abstract classes may not be instantiated, and require subclasses to provide implementations for the abstract methods.
itft-Decision making and branching in javaAtul Sehdev
Decision Making Statements,The if Statement, SIMPLE IF STATEMENT, The If…else Statement, Nesting of IF..Else Statements, THE else if ladder, The Switch Statement, rules apply to a switch statement
Swing is a GUI widget toolkit for Java. It is part of Oracle's Java Foundation Classes (JFC) – an API for providing a graphical user interface (GUI) for Java programs.
In the Java programming language, the final keyword is used in several different contexts to define an entity that can only be assigned once. Once a final variable has been assigned, it always contains the same value.
Java abstract class & abstract methods,Abstract class in java
Abstract classes are classes that contain one or more abstract methods. An abstract method is a method that is declared, but contains no implementation. Abstract classes may not be instantiated, and require subclasses to provide implementations for the abstract methods.
02slidLarge value of face area Large value of face areaAhmadHashlamon
Large value of face area Large value of face area Large value of face area Large value of face area Large value of face area Large value of face area Large value of face area Large value of face area Large value of face area Large value of face area Large value of face area Large value of face area Large value of face area Large value of face area Large value of face area Large value of face area Large value of face area Large value of face area Large value of face area Large value of face area Large value of face area Large value of face area Large value of face area Large value of face area Large value of face area Large value of face area Large value of face area Large value of face area Large value of face area Large value of face area Large value of face area Large value of face area
To write Java programs to perform simple calculations (§2.2).
To obtain input from the console using the Scanner class (§2.3).
To use identifiers to name variables, constants, methods, and classes (§2.4).
To use variables to store data (§§2.5-2.6).
To program with assignment statements and assignment expressions (§2.6).
To use constants to store permanent data (§2.7).
To declare Java primitive data types: byte, short, int, long, float, double, and char (§§2.8.1).
To use Java operators to write numeric expressions (§§2.8.2–2.8.3).
To display current time (§2.9).
To use short hand operators (§2.10).
To cast value of one type to another type (§2.11).
To compute loan payment (§2.12).
To represent characters using the char type (§2.13).
To compute monetary changes (§2.14).
To represent a string using the String type (§2.15).
To become familiar with Java documentation, programming style, and naming conventions (§2.16).
To distinguish syntax errors, runtime errors, and logic errors and debug errors (§2.17).
(GUI) To obtain input using the JOptionPane input dialog boxes (§2.18).
Dev Dives: Train smarter, not harder – active learning and UiPath LLMs for do...UiPathCommunity
💥 Speed, accuracy, and scaling – discover the superpowers of GenAI in action with UiPath Document Understanding and Communications Mining™:
See how to accelerate model training and optimize model performance with active learning
Learn about the latest enhancements to out-of-the-box document processing – with little to no training required
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👨🏫 Andras Palfi, Senior Product Manager, UiPath
👩🏫 Lenka Dulovicova, Product Program Manager, UiPath
Essentials of Automations: Optimizing FME Workflows with ParametersSafe Software
Are you looking to streamline your workflows and boost your projects’ efficiency? Do you find yourself searching for ways to add flexibility and control over your FME workflows? If so, you’re in the right place.
Join us for an insightful dive into the world of FME parameters, a critical element in optimizing workflow efficiency. This webinar marks the beginning of our three-part “Essentials of Automation” series. This first webinar is designed to equip you with the knowledge and skills to utilize parameters effectively: enhancing the flexibility, maintainability, and user control of your FME projects.
Here’s what you’ll gain:
- Essentials of FME Parameters: Understand the pivotal role of parameters, including Reader/Writer, Transformer, User, and FME Flow categories. Discover how they are the key to unlocking automation and optimization within your workflows.
- Practical Applications in FME Form: Delve into key user parameter types including choice, connections, and file URLs. Allow users to control how a workflow runs, making your workflows more reusable. Learn to import values and deliver the best user experience for your workflows while enhancing accuracy.
- Optimization Strategies in FME Flow: Explore the creation and strategic deployment of parameters in FME Flow, including the use of deployment and geometry parameters, to maximize workflow efficiency.
- Pro Tips for Success: Gain insights on parameterizing connections and leveraging new features like Conditional Visibility for clarity and simplicity.
We’ll wrap up with a glimpse into future webinars, followed by a Q&A session to address your specific questions surrounding this topic.
Don’t miss this opportunity to elevate your FME expertise and drive your projects to new heights of efficiency.
Securing your Kubernetes cluster_ a step-by-step guide to success !KatiaHIMEUR1
Today, after several years of existence, an extremely active community and an ultra-dynamic ecosystem, Kubernetes has established itself as the de facto standard in container orchestration. Thanks to a wide range of managed services, it has never been so easy to set up a ready-to-use Kubernetes cluster.
However, this ease of use means that the subject of security in Kubernetes is often left for later, or even neglected. This exposes companies to significant risks.
In this talk, I'll show you step-by-step how to secure your Kubernetes cluster for greater peace of mind and reliability.
Kubernetes & AI - Beauty and the Beast !?! @KCD Istanbul 2024Tobias Schneck
As AI technology is pushing into IT I was wondering myself, as an “infrastructure container kubernetes guy”, how get this fancy AI technology get managed from an infrastructure operational view? Is it possible to apply our lovely cloud native principals as well? What benefit’s both technologies could bring to each other?
Let me take this questions and provide you a short journey through existing deployment models and use cases for AI software. On practical examples, we discuss what cloud/on-premise strategy we may need for applying it to our own infrastructure to get it to work from an enterprise perspective. I want to give an overview about infrastructure requirements and technologies, what could be beneficial or limiting your AI use cases in an enterprise environment. An interactive Demo will give you some insides, what approaches I got already working for real.
Builder.ai Founder Sachin Dev Duggal's Strategic Approach to Create an Innova...Ramesh Iyer
In today's fast-changing business world, Companies that adapt and embrace new ideas often need help to keep up with the competition. However, fostering a culture of innovation takes much work. It takes vision, leadership and willingness to take risks in the right proportion. Sachin Dev Duggal, co-founder of Builder.ai, has perfected the art of this balance, creating a company culture where creativity and growth are nurtured at each stage.
Epistemic Interaction - tuning interfaces to provide information for AI supportAlan Dix
Paper presented at SYNERGY workshop at AVI 2024, Genoa, Italy. 3rd June 2024
https://alandix.com/academic/papers/synergy2024-epistemic/
As machine learning integrates deeper into human-computer interactions, the concept of epistemic interaction emerges, aiming to refine these interactions to enhance system adaptability. This approach encourages minor, intentional adjustments in user behaviour to enrich the data available for system learning. This paper introduces epistemic interaction within the context of human-system communication, illustrating how deliberate interaction design can improve system understanding and adaptation. Through concrete examples, we demonstrate the potential of epistemic interaction to significantly advance human-computer interaction by leveraging intuitive human communication strategies to inform system design and functionality, offering a novel pathway for enriching user-system engagements.
Encryption in Microsoft 365 - ExpertsLive Netherlands 2024Albert Hoitingh
In this session I delve into the encryption technology used in Microsoft 365 and Microsoft Purview. Including the concepts of Customer Key and Double Key Encryption.
Software Delivery At the Speed of AI: Inflectra Invests In AI-Powered QualityInflectra
In this insightful webinar, Inflectra explores how artificial intelligence (AI) is transforming software development and testing. Discover how AI-powered tools are revolutionizing every stage of the software development lifecycle (SDLC), from design and prototyping to testing, deployment, and monitoring.
Learn about:
• The Future of Testing: How AI is shifting testing towards verification, analysis, and higher-level skills, while reducing repetitive tasks.
• Test Automation: How AI-powered test case generation, optimization, and self-healing tests are making testing more efficient and effective.
• Visual Testing: Explore the emerging capabilities of AI in visual testing and how it's set to revolutionize UI verification.
• Inflectra's AI Solutions: See demonstrations of Inflectra's cutting-edge AI tools like the ChatGPT plugin and Azure Open AI platform, designed to streamline your testing process.
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JMeter webinar - integration with InfluxDB and GrafanaRTTS
Watch this recorded webinar about real-time monitoring of application performance. See how to integrate Apache JMeter, the open-source leader in performance testing, with InfluxDB, the open-source time-series database, and Grafana, the open-source analytics and visualization application.
In this webinar, we will review the benefits of leveraging InfluxDB and Grafana when executing load tests and demonstrate how these tools are used to visualize performance metrics.
Length: 30 minutes
Session Overview
-------------------------------------------
During this webinar, we will cover the following topics while demonstrating the integrations of JMeter, InfluxDB and Grafana:
- What out-of-the-box solutions are available for real-time monitoring JMeter tests?
- What are the benefits of integrating InfluxDB and Grafana into the load testing stack?
- Which features are provided by Grafana?
- Demonstration of InfluxDB and Grafana using a practice web application
To view the webinar recording, go to:
https://www.rttsweb.com/jmeter-integration-webinar
JMeter webinar - integration with InfluxDB and Grafana
Ch2 Liang
1. Chapter 2 Elementary Programming
Liang, Introduction to Java Programming, Ninth Edition, (c) 2013 Pearson Education, Inc. All
rights reserved.
1
2. Motivations
In the preceding chapter, you learned how to
create, compile, and run a Java program. Starting
from this chapter, you will learn how to solve
practical problems programmatically. Through
these problems, you will learn Java primitive data
types and related subjects, such as variables,
constants, data types, operators, expressions, and
input and output.
Liang, Introduction to Java Programming, Ninth Edition, (c) 2013 Pearson Education, Inc. All
rights reserved.
2
3. Objectives
To write Java programs to perform simple computations (§2.2).
To obtain input from the console using the Scanner class (§2.3).
To use identifiers to name variables, constants, methods, and classes (§2.4).
To use variables to store data (§§2.5–2.6).
To program with assignment statements and assignment expressions (§2.6).
To use constants to store permanent data (§2.7).
To name classes, methods, variables, and constants by following their naming conventions (§2.8).
To explore Java numeric primitive data types: byte, short, int, long, float, and double (§2.9.1).
To perform operations using operators +, -, *, /, and % (§2.9.2).
To perform exponent operations using Math.pow(a, b) (§2.9.3).
To write integer literals, floating-point literals, and literals in scientific notation (§2.10).
To write and evaluate numeric expressions (§2.11).
To obtain the current system time using System.currentTimeMillis() (§2.12).
To use augmented assignment operators (§2.13).
To distinguish between postincrement and preincrement and between postdecrement and
predecrement (§2.14).
To cast the value of one type to another type (§2.15).
To describe the software development process and apply it to develop the loan payment program
(§2.16).
To represent characters using the char type (§2.17).
To represent a string using the String type (§2.18).
To obtain input using the JOptionPane input dialog boxes (§2.19).
Liang, Introduction to Java Programming, Ninth Edition, (c) 2013 Pearson Education, Inc. All
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3
4. Introducing Programming with an
Example
Listing 2.1 Computing the Area of a Circle
This program computes the area of the circle.
ComputeArea
IMPORTANT NOTE: (1) To enable the buttons, you must
Run download the entire slide file slide.zip and unzip the files into a
directory (e.g., c:slide) . (2) You must have installed JDK and set
JDK’s bin directory in your environment path (e.g., c:Program
Filesjavajdk1.7.0bin in your environment path. (3) If you are
using Office 2010, check PowerPoint2010.doc located in the same
folder with this ppt file.
Liang, Introduction to Java Programming, Ninth Edition, (c) 2013 Pearson Education, Inc. All
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4
5. animation
Trace a Program Execution
public class ComputeArea { allocate memory
/** Main method */ for radius
public static void main(String[] args) {
double radius; radius no value
double area;
// Assign a radius
radius = 20;
// Compute area
area = radius * radius * 3.14159;
// Display results
System.out.println("The area for the circle of radius " +
radius + " is " + area);
}
}
Liang, Introduction to Java Programming, Ninth Edition, (c) 2013 Pearson Education, Inc. All
rights reserved.
5
6. animation
Trace a Program Execution
public class ComputeArea {
/** Main method */ memory
public static void main(String[] args) {
double radius; radius no value
double area; area no value
// Assign a radius
radius = 20;
allocate memory
// Compute area for area
area = radius * radius * 3.14159;
// Display results
System.out.println("The area for the circle of radius " +
radius + " is " + area);
}
}
Liang, Introduction to Java Programming, Ninth Edition, (c) 2013 Pearson Education, Inc. All
rights reserved.
6
7. animation
Trace a Program Execution
public class ComputeArea { assign 20 to radius
/** Main method */
public static void main(String[] args) {
double radius; radius 20
double area; area no value
// Assign a radius
radius = 20;
// Compute area
area = radius * radius * 3.14159;
// Display results
System.out.println("The area for the circle of radius " +
radius + " is " + area);
}
}
Liang, Introduction to Java Programming, Ninth Edition, (c) 2013 Pearson Education, Inc. All
rights reserved.
7
8. animation
Trace a Program Execution
public class ComputeArea {
/** Main method */ memory
public static void main(String[] args) {
double radius; radius 20
double area; area 1256.636
// Assign a radius
radius = 20;
compute area and assign it
// Compute area
to variable area
area = radius * radius * 3.14159;
// Display results
System.out.println("The area for the circle of radius " +
radius + " is " + area);
}
}
Liang, Introduction to Java Programming, Ninth Edition, (c) 2013 Pearson Education, Inc. All
rights reserved.
8
9. animation
Trace a Program Execution
public class ComputeArea {
/** Main method */ memory
public static void main(String[] args) {
double radius; radius 20
double area; area 1256.636
// Assign a radius
radius = 20;
// Compute area
area = radius * radius * 3.14159; print a message to the
console
// Display results
System.out.println("The area for the circle of radius " +
radius + " is " + area);
}
}
Liang, Introduction to Java Programming, Ninth Edition, (c) 2013 Pearson Education, Inc. All
rights reserved.
9
10. Reading Input from the Console
1. Create a Scanner object
Scanner input = new Scanner(System.in);
2. Use the methods next(), nextByte(), nextShort(),
nextInt(), nextLong(), nextFloat(), nextDouble(), or
nextBoolean() to obtain to a string, byte, short, int, long,
float, double, or boolean value. For example,
System.out.print("Enter a double value: ");
Scanner input = new Scanner(System.in);
double d = input.nextDouble();
ComputeAreaWithConsoleInput ComputeAverage
Run Run
Liang, Introduction to Java Programming, Ninth Edition, (c) 2013 Pearson Education, Inc. All
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10
11. Identifiers
An identifier is a sequence of characters that consist of
letters, digits, underscores (_), and dollar signs ($).
An identifier must start with a letter, an underscore (_),
or a dollar sign ($). It cannot start with a digit.
– An identifier cannot be a reserved word. (See Appendix A,
“Java Keywords,” for a list of reserved words).
An identifier cannot be true, false, or
null.
An identifier can be of any length.
Liang, Introduction to Java Programming, Ninth Edition, (c) 2013 Pearson Education, Inc. All
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11
12. Variables
// Compute the first area
radius = 1.0;
area = radius * radius * 3.14159;
System.out.println("The area is “ +
area + " for radius "+radius);
// Compute the second area
radius = 2.0;
area = radius * radius * 3.14159;
System.out.println("The area is “ +
area + " for radius "+radius);
Liang, Introduction to Java Programming, Ninth Edition, (c) 2013 Pearson Education, Inc. All
rights reserved.
12
13. Declaring Variables
int x; // Declare x to be an
// integer variable;
double radius; // Declare radius to
// be a double variable;
char a; // Declare a to be a
// character variable;
Liang, Introduction to Java Programming, Ninth Edition, (c) 2013 Pearson Education, Inc. All
rights reserved.
13
14. Assignment Statements
x = 1; // Assign 1 to x;
radius = 1.0; // Assign 1.0 to radius;
a = 'A'; // Assign 'A' to a;
Liang, Introduction to Java Programming, Ninth Edition, (c) 2013 Pearson Education, Inc. All
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14
15. Declaring and Initializing
in One Step
int x = 1;
double d = 1.4;
Liang, Introduction to Java Programming, Ninth Edition, (c) 2013 Pearson Education, Inc. All
rights reserved.
15
16. Named Constants
final datatype CONSTANTNAME = VALUE;
final double PI = 3.14159;
final int SIZE = 3;
Liang, Introduction to Java Programming, Ninth Edition, (c) 2013 Pearson Education, Inc. All
rights reserved.
16
17. Naming Conventions
Choose meaningful and descriptive names.
Variables and method names:
– Use lowercase. If the name consists of several
words, concatenate all in one, use lowercase
for the first word, and capitalize the first letter
of each subsequent word in the name. For
example, the variables radius and area, and
the method computeArea.
Liang, Introduction to Java Programming, Ninth Edition, (c) 2013 Pearson Education, Inc. All
rights reserved.
17
18. Naming Conventions, cont.
Class names:
– Capitalize the first letter of each word in
the name. For example, the class name
ComputeArea.
Constants:
– Capitalize all letters in constants, and use
underscores to connect words. For
example, the constant PI and
MAX_VALUE
Liang, Introduction to Java Programming, Ninth Edition, (c) 2013 Pearson Education, Inc. All
rights reserved.
18
19. Numerical Data Types
Name Range Storage Size
byte –27 to 27 – 1 (-128 to 127) 8-bit signed
short –215 to 215 – 1 (-32768 to 32767) 16-bit signed
int –231 to 231 – 1 (-2147483648 to 2147483647) 32-bit signed
long –263 to 263 – 1 64-bit signed
(i.e., -9223372036854775808 to 9223372036854775807)
float Negative range: 32-bit IEEE 754
-3.4028235E+38 to -1.4E-45
Positive range:
1.4E-45 to 3.4028235E+38
double Negative range: 64-bit IEEE 754
-1.7976931348623157E+308 to -4.9E-324
Positive range:
4.9E-324 to 1.7976931348623157E+308
Liang, Introduction to Java Programming, Ninth Edition, (c) 2013 Pearson Education, Inc. All
rights reserved.
19
20. Numeric Operators
Name Meaning Example Result
+ Addition 34 + 1 35
- Subtraction 34.0 – 0.1 33.9
* Multiplication 300 * 30 9000
/ Division 1.0 / 2.0 0.5
% Remainder 20 % 3 2
Liang, Introduction to Java Programming, Ninth Edition, (c) 2013 Pearson Education, Inc. All
rights reserved.
20
21. Integer Division
+, -, *, /, and %
5 / 2 yields an integer 2.
5.0 / 2 yields a double value 2.5
5 % 2 yields 1 (the remainder of the division)
Liang, Introduction to Java Programming, Ninth Edition, (c) 2013 Pearson Education, Inc. All
rights reserved.
21
22. Remainder Operator
Remainder is very useful in programming. For example, an
even number % 2 is always 0 and an odd number % 2 is always
1. So you can use this property to determine whether a number
is even or odd. Suppose today is Saturday and you and your
friends are going to meet in 10 days. What day is in 10
days? You can find that day is Tuesday using the following
expression:
Saturday is the 6th day in a week
A week has 7 days
(6 + 10) % 7 is 2
The 2nd day in a week is Tuesday
After 10 days
Liang, Introduction to Java Programming, Ninth Edition, (c) 2013 Pearson Education, Inc. All
rights reserved.
22
23. Problem: Displaying Time
Write a program that obtains hours and
minutes from seconds.
DisplayTime Run
Liang, Introduction to Java Programming, Ninth Edition, (c) 2013 Pearson Education, Inc. All
rights reserved.
23
24. NOTE
Calculations involving floating-point numbers are
approximated because these numbers are not stored
with complete accuracy. For example,
System.out.println(1.0 - 0.1 - 0.1 - 0.1 - 0.1 - 0.1);
displays 0.5000000000000001, not 0.5, and
System.out.println(1.0 - 0.9);
displays 0.09999999999999998, not 0.1. Integers are
stored precisely. Therefore, calculations with integers
yield a precise integer result.
Liang, Introduction to Java Programming, Ninth Edition, (c) 2013 Pearson Education, Inc. All
rights reserved.
24
25. Exponent Operations
System.out.println(Math.pow(2, 3));
// Displays 8.0
System.out.println(Math.pow(4, 0.5));
// Displays 2.0
System.out.println(Math.pow(2.5, 2));
// Displays 6.25
System.out.println(Math.pow(2.5, -2));
// Displays 0.16
Liang, Introduction to Java Programming, Ninth Edition, (c) 2013 Pearson Education, Inc. All
rights reserved.
25
26. Number Literals
A literal is a constant value that appears directly
in the program. For example, 34, 1,000,000, and
5.0 are literals in the following statements:
int i = 34;
long x = 1000000;
double d = 5.0;
Liang, Introduction to Java Programming, Ninth Edition, (c) 2013 Pearson Education, Inc. All
rights reserved.
26
27. Integer Literals
An integer literal can be assigned to an integer variable as
long as it can fit into the variable. A compilation error
would occur if the literal were too large for the variable to
hold. For example, the statement byte b = 1000 would
cause a compilation error, because 1000 cannot be stored
in a variable of the byte type.
An integer literal is assumed to be of the int type, whose
value is between -231 (-2147483648) to 231–1
(2147483647). To denote an integer literal of the long
type, append it with the letter L or l. L is preferred because
l (lowercase L) can easily be confused with 1 (the digit
one).
Liang, Introduction to Java Programming, Ninth Edition, (c) 2013 Pearson Education, Inc. All
rights reserved.
27
28. Floating-Point Literals
Floating-point literals are written with a decimal
point. By default, a floating-point literal is treated
as a double type value. For example, 5.0 is
considered a double value, not a float value. You
can make a number a float by appending the letter f
or F, and make a number a double by appending
the letter d or D. For example, you can use 100.2f
or 100.2F for a float number, and 100.2d or 100.2D
for a double number.
Liang, Introduction to Java Programming, Ninth Edition, (c) 2013 Pearson Education, Inc. All
rights reserved.
28
29. Scientific Notation
Floating-point literals can also be specified in
scientific notation, for example, 1.23456e+2,
same as 1.23456e2, is equivalent to 123.456, and
1.23456e-2 is equivalent to 0.0123456. E (or e)
represents an exponent and it can be either in
lowercase or uppercase.
Liang, Introduction to Java Programming, Ninth Edition, (c) 2013 Pearson Education, Inc. All
rights reserved.
29
30. Arithmetic Expressions
3 4x 10 ( y 5)( a b c) 4 9 x
9( )
5 x x y
is translated to
(3+4*x)/5 – 10*(y-5)*(a+b+c)/x + 9*(4/x + (9+x)/y)
Liang, Introduction to Java Programming, Ninth Edition, (c) 2013 Pearson Education, Inc. All
rights reserved.
30
31. How to Evaluate an Expression
Though Java has its own way to evaluate an
expression behind the scene, the result of a Java
expression and its corresponding arithmetic expression
are the same. Therefore, you can safely apply the
arithmetic rule for evaluating a Java expression.
3 + 4 * 4 + 5 * (4 + 3) - 1
(1) inside parentheses first
3 + 4 * 4 + 5 * 7 – 1
(2) multiplication
3 + 16 + 5 * 7 – 1
(3) multiplication
3 + 16 + 35 – 1
(4) addition
19 + 35 – 1
(5) addition
54 - 1
(6) subtraction
53
Liang, Introduction to Java Programming, Ninth Edition, (c) 2013 Pearson Education, Inc. All
rights reserved.
31
32. Problem: Converting Temperatures
Write a program that converts a Fahrenheit degree
to Celsius using the formula:
5
celsius ( 9 )( fahrenheit 32 )
Note: you have to write
celsius = (5.0 / 9) * (fahrenheit – 32)
FahrenheitToCelsius Run
Liang, Introduction to Java Programming, Ninth Edition, (c) 2013 Pearson Education, Inc. All
rights reserved.
32
33. Problem: Displaying Current Time
Write a program that displays current time in GMT in the
format hour:minute:second such as 1:45:19.
The currentTimeMillis method in the System class returns
the current time in milliseconds since the midnight, January
1, 1970 GMT. (1970 was the year when the Unix operating
system was formally introduced.) You can use this method
to obtain the current time, and then compute the current
second, minute, and hour as follows.
Elapsed
time
ShowCurrentTime
Time
Unix Epoch Current Time
01-01-1970
00:00:00 GMT
System.currentTimeMills() Run
Liang, Introduction to Java Programming, Ninth Edition, (c) 2013 Pearson Education, Inc. All
rights reserved.
33
34. Shortcut Assignment Operators
Operator Example Equivalent
+= i += 8 i = i + 8
-= f -= 8.0 f = f - 8.0
*= i *= 8 i = i * 8
/= i /= 8 i = i / 8
%= i %= 8 i = i % 8
Liang, Introduction to Java Programming, Ninth Edition, (c) 2013 Pearson Education, Inc. All
rights reserved.
34
35. Increment and
Decrement Operators
Operator Name Description
++var preincrement The expression (++var) increments var by 1 and evaluates
to the new value in var after the increment.
var++ postincrement The expression (var++) evaluates to the original value
in var and increments var by 1.
--var predecrement The expression (--var) decrements var by 1 and evaluates
to the new value in var after the decrement.
var-- postdecrement The expression (var--) evaluates to the original value
in var and decrements var by 1.
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36. Increment and
Decrement Operators, cont.
int i = 10; Same effect as
int newNum = 10 * i++; int newNum = 10 * i;
i = i + 1;
int i = 10; Same effect as
int newNum = 10 * (++i); i = i + 1;
int newNum = 10 * i;
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36
37. Increment and
Decrement Operators, cont.
Using increment and decrement operators makes
expressions short, but it also makes them complex and
difficult to read. Avoid using these operators in expressions
that modify multiple variables, or the same variable for
multiple times such as this: int k = ++i + i.
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37
38. Assignment Expressions and
Assignment Statements
Prior to Java 2, all the expressions can be used as
statements. Since Java 2, only the following types of
expressions can be statements:
variable op= expression; // Where op is +, -, *, /, or %
++variable;
variable++;
--variable;
variable--;
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38
39. Numeric Type Conversion
Consider the following statements:
byte i = 100;
long k = i * 3 + 4;
double d = i * 3.1 + k / 2;
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39
40. Conversion Rules
When performing a binary operation involving two
operands of different types, Java automatically
converts the operand based on the following rules:
1. If one of the operands is double, the other is
converted into double.
2. Otherwise, if one of the operands is float, the other is
converted into float.
3. Otherwise, if one of the operands is long, the other is
converted into long.
4. Otherwise, both operands are converted into int.
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40
41. Type Casting
Implicit casting
double d = 3; (type widening)
Explicit casting
int i = (int)3.0; (type narrowing)
int i = (int)3.9; (Fraction part is
truncated)
What is wrong? int x = 5 / 2.0;
range increases
byte, short, int, long, float, double
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41
42. Problem: Keeping Two Digits After
Decimal Points
Write a program that displays the sales tax with two
digits after the decimal point.
SalesTax Run
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42
43. Casting in an Augmented Expression
In Java, an augmented expression of the form x1 op=
x2 is implemented as x1 = (T)(x1 op x2), where T is
the type for x1. Therefore, the following code is
correct.
int sum = 0;
sum += 4.5; // sum becomes 4 after this statement
sum += 4.5 is equivalent to sum = (int)(sum + 4.5).
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43
44. Software Development Process
Requirement
Specification
System
Analysis
System
Design
Implementation
Testing
Deployment
Maintenance
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44
45. Requirement Specification
A formal process that seeks to understand
Requirement
Specification
the problem and document in detail what
the software system needs to do. This
System phase involves close interaction between
Analysis
users and designers.
System
Design
Implementation
Testing
Most of the examples in this book are simple,
and their requirements are clearly stated. In Deployment
the real world, however, problems are not
well defined. You need to study a problem Maintenance
carefully to identify its requirements.
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45
46. System Analysis
Requirement
Specification Seeks to analyze the business
process in terms of data flow, and
System
Analysis to identify the system’s input and
output.
System
Design
Implementation
Testing
Part of the analysis entails modeling
the system’s behavior. The model is
Deployment
intended to capture the essential
elements of the system and to define
Maintenance
services to the system.
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46
47. System Design
Requirement
Specification
The process of designing the
system’s components.
System
Analysis
System
Design
Implementation
Testing
This phase involves the use of many levels
Deployment
of abstraction to decompose the problem into
manageable components, identify classes and
interfaces, and establish relationships among Maintenance
the classes and interfaces.
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47
48. IPO
Requirement
Specification
System
Analysis Input, Process, Output
System
Design
Implementation
Testing
The essence of system analysis and design is input,
process, and output. This is called IPO. Deployment
Maintenance
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48
49. Implementation
Requirement The process of translating the
Specification
system design into programs.
System Separate programs are written for
Analysis
each component and put to work
System together.
Design
Implementation
Testing
This phase requires the use of a
programming language like Java. Deployment
The implementation involves
coding, testing, and debugging. Maintenance
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49
50. Testing
Requirement
Specification Ensures that the code meets the
requirements specification and
System
Analysis weeds out bugs.
System
Design
Implementation
Testing
An independent team of software
engineers not involved in the design Deployment
and implementation of the project
usually conducts such testing. Maintenance
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50
51. Deployment
Requirement
Specification Deployment makes the project
available for use.
System
Analysis
System
Design
Implementation
Testing
For a Java applet, this means
installing it on a Web server; for a Deployment
Java application, installing it on the
client's computer. Maintenance
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51
52. Maintenance
Requirement
Specification Maintenance is concerned with
changing and improving the
System
Analysis product.
System
Design
Implementation
Testing
A software product must continue to
perform and improve in a changing Deployment
environment. This requires periodic
upgrades of the product to fix newly Maintenance
discovered bugs and incorporate changes.
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52
53. Problem:
Computing Loan Payments
This program lets the user enter the interest
rate, number of years, and loan amount, and
computes monthly payment and total
payment.
loanAmount monthlyInterestRate
monthlyPayment
1 1
numberOfYears 12
(1 monthlyInterestRate)
ComputeLoan Run
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53
54. Character Data Type
Four hexadecimal digits.
char letter = 'A'; (ASCII)
char numChar = '4'; (ASCII)
char letter = 'u0041'; (Unicode)
char numChar = 'u0034'; (Unicode)
NOTE: The increment and decrement operators can also be used
on char variables to get the next or preceding Unicode character.
For example, the following statements display character b.
char ch = 'a';
System.out.println(++ch);
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54
55. Unicode Format
Java characters use Unicode, a 16-bit encoding scheme
established by the Unicode Consortium to support the
interchange, processing, and display of written texts in the
world’s diverse languages. Unicode takes two bytes,
preceded by u, expressed in four hexadecimal numbers
that run from 'u0000' to 'uFFFF'. So, Unicode can
represent 65535 + 1 characters.
Unicode u03b1 u03b2 u03b3 for three Greek
letters
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55
56. Problem: Displaying Unicodes
Write a program that displays two Chinese
characters and three Greek letters.
DisplayUnicode Run
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56
57. Escape Sequences for Special Characters
Description Escape Sequence Unicode
Backspace b u0008
Tab t u0009
Linefeed n u000A
Carriage return r u000D
Backslash u005C
Single Quote ' u0027
Double Quote " u0022
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58. Appendix B: ASCII Character Set
ASCII Character Set is a subset of the Unicode from u0000 to u007f
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58
59. ASCII Character Set, cont.
ASCII Character Set is a subset of the Unicode from u0000 to u007f
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59
60. Casting between char and
Numeric Types
int i = 'a'; // Same as int i = (int)'a';
char c = 97; // Same as char c = (char)97;
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60
61. Problem: Monetary Units
This program lets the user enter the amount in
decimal representing dollars and cents and output
a report listing the monetary equivalent in single
dollars, quarters, dimes, nickels, and pennies.
Your program should report maximum number of
dollars, then the maximum number of quarters,
and so on, in this order.
ComputeChange Run
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61
62. Trace ComputeChange
Suppose amount is 11.56
int remainingAmount = (int)(amount * 100); remainingAmount 1156
// Find the number of one dollars
int numberOfOneDollars = remainingAmount / 100;
remainingAmount
remainingAmount = remainingAmount % 100;
initialized
// Find the number of quarters in the remaining amount
int numberOfQuarters = remainingAmount / 25;
remainingAmount = remainingAmount % 25;
// Find the number of dimes in the remaining amount
int numberOfDimes = remainingAmount / 10;
remainingAmount = remainingAmount % 10;
// Find the number of nickels in the remaining amount
int numberOfNickels = remainingAmount / 5;
remainingAmount = remainingAmount % 5;
// Find the number of pennies in the remaining amount
int numberOfPennies = remainingAmount;
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62
63. animation
Trace ComputeChange
Suppose amount is 11.56
int remainingAmount = (int)(amount * 100); remainingAmount 1156
// Find the number of one dollars
int numberOfOneDollars = remainingAmount / 100; numberOfOneDollars 11
remainingAmount = remainingAmount % 100;
// Find the number of quarters in the remaining amount numberOfOneDollars
int numberOfQuarters = remainingAmount / 25; assigned
remainingAmount = remainingAmount % 25;
// Find the number of dimes in the remaining amount
int numberOfDimes = remainingAmount / 10;
remainingAmount = remainingAmount % 10;
// Find the number of nickels in the remaining amount
int numberOfNickels = remainingAmount / 5;
remainingAmount = remainingAmount % 5;
// Find the number of pennies in the remaining amount
int numberOfPennies = remainingAmount;
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63
64. animation
Trace ComputeChange
Suppose amount is 11.56
int remainingAmount = (int)(amount * 100); remainingAmount 56
// Find the number of one dollars
int numberOfOneDollars = remainingAmount / 100; numberOfOneDollars 11
remainingAmount = remainingAmount % 100;
// Find the number of quarters in the remaining amount
int numberOfQuarters = remainingAmount / 25; remainingAmount
remainingAmount = remainingAmount % 25; updated
// Find the number of dimes in the remaining amount
int numberOfDimes = remainingAmount / 10;
remainingAmount = remainingAmount % 10;
// Find the number of nickels in the remaining amount
int numberOfNickels = remainingAmount / 5;
remainingAmount = remainingAmount % 5;
// Find the number of pennies in the remaining amount
int numberOfPennies = remainingAmount;
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64
65. animation
Trace ComputeChange
Suppose amount is 11.56
int remainingAmount = (int)(amount * 100); remainingAmount 56
// Find the number of one dollars
int numberOfOneDollars = remainingAmount / 100; numberOfOneDollars 11
remainingAmount = remainingAmount % 100;
// Find the number of quarters in the remaining amount
int numberOfQuarters = remainingAmount / 25; numberOfOneQuarters 2
remainingAmount = remainingAmount % 25;
// Find the number of dimes in the remaining amount numberOfOneQuarters
int numberOfDimes = remainingAmount / 10; assigned
remainingAmount = remainingAmount % 10;
// Find the number of nickels in the remaining amount
int numberOfNickels = remainingAmount / 5;
remainingAmount = remainingAmount % 5;
// Find the number of pennies in the remaining amount
int numberOfPennies = remainingAmount;
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65
66. animation
Trace ComputeChange
Suppose amount is 11.56
int remainingAmount = (int)(amount * 100); remainingAmount 6
// Find the number of one dollars
int numberOfOneDollars = remainingAmount / 100; numberOfOneDollars 11
remainingAmount = remainingAmount % 100;
// Find the number of quarters in the remaining amount
int numberOfQuarters = remainingAmount / 25; numberOfQuarters 2
remainingAmount = remainingAmount % 25;
// Find the number of dimes in the remaining amount
int numberOfDimes = remainingAmount / 10; remainingAmount
remainingAmount = remainingAmount % 10; updated
// Find the number of nickels in the remaining amount
int numberOfNickels = remainingAmount / 5;
remainingAmount = remainingAmount % 5;
// Find the number of pennies in the remaining amount
int numberOfPennies = remainingAmount;
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66
67. The String Type
The char type only represents one character. To represent a string
of characters, use the data type called String. For example,
String message = "Welcome to Java";
String is actually a predefined class in the Java library just like the
System class and JOptionPane class. The String type is not a
primitive type. It is known as a reference type. Any Java class can
be used as a reference type for a variable. Reference data types
will be thoroughly discussed in Chapter 8, “Objects and Classes.”
For the time being, you just need to know how to declare a String
variable, how to assign a string to the variable, and how to
concatenate strings.
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67
68. String Concatenation
// Three strings are concatenated
String message = "Welcome " + "to " + "Java";
// String Chapter is concatenated with number 2
String s = "Chapter" + 2; // s becomes Chapter2
// String Supplement is concatenated with character B
String s1 = "Supplement" + 'B'; // s1 becomes SupplementB
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68
69. Debugging
Logic errors are called bugs. The process of finding and
correcting errors is called debugging. A common approach
to debugging is to use a combination of methods to narrow
down to the part of the program where the bug is located.
You can hand-trace the program (i.e., catch errors by
reading the program), or you can insert print statements in
order to show the values of the variables or the execution
flow of the program. This approach might work for a
short, simple program. But for a large, complex program,
the most effective approach for debugging is to use a
debugger utility.
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70. Debugger
Debugger is a program that facilitates debugging.
You can use a debugger to
Execute a single statement at a time.
Trace into or stepping over a method.
Set breakpoints.
Display variables.
Display call stack.
Modify variables.
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71. JOptionPane Input
This book provides two ways of obtaining input.
1. Using the Scanner class (console input)
2. Using JOptionPane input dialogs
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72. Getting Input from Input Dialog Boxes
String input = JOptionPane.showInputDialog(
"Enter an input");
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73. Getting Input from Input Dialog Boxes
String string = JOptionPane.showInputDialog(
null, “Prompting Message”, “Dialog Title”,
JOptionPane.QUESTION_MESSAGE);
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73
74. Two Ways to Invoke the Method
There are several ways to use the showInputDialog method. For
the time being, you only need to know two ways to invoke it.
One is to use a statement as shown in the example:
String string = JOptionPane.showInputDialog(null, x,
y, JOptionPane.QUESTION_MESSAGE);
where x is a string for the prompting message, and y is a string for
the title of the input dialog box.
The other is to use a statement like this:
JOptionPane.showInputDialog(x);
where x is a string for the prompting message.
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74
75. Converting Strings to Integers
The input returned from the input dialog box is a string. If
you enter a numeric value such as 123, it returns “123”.
To obtain the input as a number, you have to convert a
string into a number.
To convert a string into an int value, you can use the
static parseInt method in the Integer class as follows:
int intValue = Integer.parseInt(intString);
where intString is a numeric string such as “123”.
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76. Converting Strings to Doubles
To convert a string into a double value, you can use the
static parseDouble method in the Double class as follows:
double doubleValue =Double.parseDouble(doubleString);
where doubleString is a numeric string such as “123.45”.
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76
77. Problem: Computing Loan Payments
Using Input Dialogs
Same as the preceding program for computing loan
payments, except that the input is entered from the
input dialogs and the output is displayed in an
output dialog.
loanAmount monthlyInterestRate
1 1
numberOfYears 12
(1 monthlyInterestRate)
ComputeLoanUsingInputDialog Run
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77
78. Companion
Website Debugging in NetBeans
Supplement II.E, Learning Java Effectively with
NetBeans
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79. Companion
Website Debugging in Eclipse
Supplement II.G, Learning Java Effectively with
NetBeans
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79