Java Object Oriented Programming Introduction to Java Programming

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Java Object Oriented Programming Introduction to Java Programming

Java Object Oriented Programming Introduction to Java Programming

Objectives: q q q Writing a Java program. How to send output to the

Objectives: q q q Writing a Java program. How to send output to the command line console. Learn how String concatenation works. Learn about escape sequences. Learn how to compile, debug, and execute a Java program. Lab 01 -2

Java Object Oriented Programming Top Down Design

Java Object Oriented Programming Top Down Design

Top Down Design q q q Start JCreator. Create a new file called “Lab

Top Down Design q q q Start JCreator. Create a new file called “Lab 01. java”. Save the new file in your Lab 01 folder. Lab 01 -4

Creating A Java Class File Lab 01 -5

Creating A Java Class File Lab 01 -5

Creating A Java Class File Lab 01 -6

Creating A Java Class File Lab 01 -6

Creating A Java Class File Lab 01 -7

Creating A Java Class File Lab 01 -7

Creating A Java Class File (cont…) Lab 01 -8

Creating A Java Class File (cont…) Lab 01 -8

Creating A Java Class File (cont…) Lab 01 -9

Creating A Java Class File (cont…) Lab 01 -9

Creating A Java Class File (cont…) Lab 01 -10

Creating A Java Class File (cont…) Lab 01 -10

Creating A Java Class File (cont…) Lab 01 -11

Creating A Java Class File (cont…) Lab 01 -11

Creating A Java Class File (cont…) Class names should always begin with an uppercase

Creating A Java Class File (cont…) Class names should always begin with an uppercase letter. Lab 01 -12

Creating A Java Class File (cont…) Click this button to set the location. Lab

Creating A Java Class File (cont…) Click this button to set the location. Lab 01 -13

Creating A Java Class File (cont…) Lab 01 -14

Creating A Java Class File (cont…) Lab 01 -14

Creating A Java Class File (cont…) Lab 01 -15

Creating A Java Class File (cont…) Lab 01 -15

Declaring A Java Class This class can be used by other classes! public class

Declaring A Java Class This class can be used by other classes! public class Lab 01 { } Lab 01 -16

Declaring A Java Class The keyword class defines this file as a Java class.

Declaring A Java Class The keyword class defines this file as a Java class. public class Lab 01 { } Lab 01 -17

Declaring A Java Class User defined name. Class names should always begin with an

Declaring A Java Class User defined name. Class names should always begin with an uppercase letter. public class Lab 01 { } Lab 01 -18

Declaring A Java Class public class Lab 01 { The body of every class

Declaring A Java Class public class Lab 01 { The body of every class begins and ends with a set of curly brackets. } Lab 01 -19

Compiling A Java Class File Lab 01 -20

Compiling A Java Class File Lab 01 -20

Compiling A Java Class File Lab 01 -21

Compiling A Java Class File Lab 01 -21

Compiling A Java Class File Lab 01 -22

Compiling A Java Class File Lab 01 -22

Running A Java Program Lab 01 -23

Running A Java Program Lab 01 -23

Running A Java Program Lab 01 -24

Running A Java Program Lab 01 -24

Running A Java Program Lab 01 -25

Running A Java Program Lab 01 -25

Java Object Oriented Programming The Main Method

Java Object Oriented Programming The Main Method

The main Method • In Java, you need to have a method named main

The main Method • In Java, you need to have a method named main in at least one class. • This method must appear within a class, but it can be any class. • A class containing a main method is a program. Every program has a main method but not every class is a program. Lab 01 -27

The main Method (cont…) public class Lab 01 { public static void main(String[ ]

The main Method (cont…) public class Lab 01 { public static void main(String[ ] args) { Curly brackets are used to define block } statements. Methods, like classes, are } block statements and must begin and end with a set of curly brackets. Lab 01 -28

The main Method (cont…) The main method is static. public class Lab 01 {

The main Method (cont…) The main method is static. public class Lab 01 { public static void main(String[ ] args) { } } Lab 01 -29

Running A Java Program Lab 01 -30

Running A Java Program Lab 01 -30

Running A Java Program Lab 01 -31

Running A Java Program Lab 01 -31

Java Object Oriented Programming Console Output

Java Object Oriented Programming Console Output

Console Output In Java, console output is achieved by calling System. out. print or

Console Output In Java, console output is achieved by calling System. out. print or System. out. println. • The data to be output is given as an argument in parentheses. System. out. println(“Blackjack”); • Every invocation of println ends a line of output. Blackjack _ Lab 01 -33

println Versus print The print method is like println, except that it does not

println Versus print The print method is like println, except that it does not end a line • With println, the next output goes on a new line • With print, the next output goes on the same line Lab 01 -34

The main Method (cont…) public class Lab 01 { public static void main(String[ ]

The main Method (cont…) public class Lab 01 { public static void main(String[ ] args) { System. out. println(“Main Method!”); } } Lab 01 -35

Running A Java Program Lab 01 -36

Running A Java Program Lab 01 -36

Java Object Oriented Programming Calling Methods

Java Object Oriented Programming Calling Methods

Calling Methods output is not static public class Lab 01 { public static void

Calling Methods output is not static public class Lab 01 { public static void main(String[ ] args) { System. out. println(“Main Method!”); } public void output() { System. out. println(“Hello World”); } } Lab 01 -38

Calling methods (cont…) Run the program public class Lab 01 { public static void

Calling methods (cont…) Run the program public class Lab 01 { public static void main(String[ ] args) { System. out. println(“Main Method!”); } public void output() { System. out. println(“Hello World”); } } Lab 01 -39

Calling methods (cont…) Lab 01 -40

Calling methods (cont…) Lab 01 -40

Calling methods (cont…) output did not execute public class Lab 01 { public static

Calling methods (cont…) output did not execute public class Lab 01 { public static void main(String[ ] args) { System. out. println(“Main Method!”); } public void output() { System. out. println(“Hello World”); } } Lab 01 -41

Calling methods (cont…) public class Lab 01 { public static void main(String[ ] args)

Calling methods (cont…) public class Lab 01 { public static void main(String[ ] args) { System. out. println(“Main Method!”); } public void output() { System. out. println(“Hello World”); } } Lab 01 -42

Calling methods (cont…) How do we get from here public class Lab 01 {

Calling methods (cont…) How do we get from here public class Lab 01 { public static void main(String[ ] args) { } public void output() { System. out. println(“Hello World”); } } Lab 01 -43

Calling methods (cont…) How do we get from here to there public class Lab

Calling methods (cont…) How do we get from here to there public class Lab 01 { public static void main(String[ ] args) { } public void output() { System. out. println(“Hello World”); } } Lab 01 -44

Calling methods (cont…) We need to call the method output() public class Lab 01

Calling methods (cont…) We need to call the method output() public class Lab 01 { public static void main(String[ ] args) { output(); } public void output() { System. out. println(“Hello World”); } } Lab 01 -45

Calling methods (cont…) Build the program public class Lab 01 { public static void

Calling methods (cont…) Build the program public class Lab 01 { public static void main(String[ ] args) { output(); } public void output() { System. out. println(“Hello World”); } } Lab 01 -46

Lab 01 -47

Lab 01 -47

error: non-static method output() cannot be referenced from a static context Lab 01 -48

error: non-static method output() cannot be referenced from a static context Lab 01 -48

Calling methods (cont…) Double click on the first line of the error. Lab 01

Calling methods (cont…) Double click on the first line of the error. Lab 01 -49

Calling methods (cont…) The editor will send the cursor to the line that contains

Calling methods (cont…) The editor will send the cursor to the line that contains the error. Lab 01 -50

Calling methods (cont…) Static methods are class methods. Non-static methods are instance methods. Class

Calling methods (cont…) Static methods are class methods. Non-static methods are instance methods. Class methods can not call instance methods – however instance methods can call class methods. More on this topic later. To be able to call output we need an instance of the class Lab 01. NOTE: An instance of a class is an OBJECT. Hence the term Object Oriented Programming. Lab 01 -51

Java Object Oriented Programming Creating an instance of a class.

Java Object Oriented Programming Creating an instance of a class.

Creating an Object Create an instance of the class public class Lab 01 {

Creating an Object Create an instance of the class public class Lab 01 { public static void main(String[ ] args) { Lab 01 lab = new Lab 01(); } public void output() { System. out. println(“Hello World”); } } Lab 01 -53

Creating an Object (cont…) lab is an object. An object is an instance of

Creating an Object (cont…) lab is an object. An object is an instance of a class. public class Lab 01 { public static void main(String[ ] args) { Lab 01 lab = new Lab 01(); } public void output() { System. out. println(“Hello World”); } } Lab 01 -54

Creating an Object (cont…) A method call to output public class Lab 01 {

Creating an Object (cont…) A method call to output public class Lab 01 { public static void main(String[ ] args) { Lab 01 lab = new Lab 01(); lab. output(); } public void output() { System. out. println(“Hello World”); } } Lab 01 -55

Creating an Object (cont…) We can call output using lab which public class Lab

Creating an Object (cont…) We can call output using lab which public class Lab 01 is an instance of the class Lab 01 { public static void main(String[ ] args) { Lab 01 lab = new Lab 01(); lab. output(); } public void output() { System. out. println(“Hello World”); } } Lab 01 -56

Run The Program Lab 01 -57

Run The Program Lab 01 -57

Java Object Oriented Programming Escape Sequencies

Java Object Oriented Programming Escape Sequencies

Escape Sequences • Escape sequences are used to print characters that are non-printable. Escape

Escape Sequences • Escape sequences are used to print characters that are non-printable. Escape sequences always begin with a (backslash) character. • Common Escape sequences n – new line ” – quote symbol t – tab \ - backslash Lab 01 -59

Escape Sequences public class Lab 01 { public static void main(String[ ] args) {

Escape Sequences public class Lab 01 { public static void main(String[ ] args) { Lab 01 lab = new Lab 01(); lab. output(); } public void output() { System. out. println(“Hellon. World”); } } Lab 01 -60

Escape Sequences (cont…) public class Lab 01 { public static void main(String[ ] args)

Escape Sequences (cont…) public class Lab 01 { public static void main(String[ ] args) { Lab 01 lab = new Lab 01(); lab. output(); } public void output() { System. out. println(“Hello\World”); } } Lab 01 -61

Escape Sequences (cont…) public class Lab 01 { public static void main(String[ ] args)

Escape Sequences (cont…) public class Lab 01 { public static void main(String[ ] args) { Lab 01 lab = new Lab 01(); lab. output(); } public void output() { System. out. println(““Hello World””); } } Lab 01 -62

Java Object Oriented Programming String Concatenation

Java Object Oriented Programming String Concatenation

String Concatenation public class Lab 01 { public static void main(String[ ] args) {

String Concatenation public class Lab 01 { public static void main(String[ ] args) { Lab 01 lab = new Lab 01(); lab. output(); } public void output() { System. out. println(“Hello World” + 1 + 2); } } Lab 01 -64

String Concatenation (cont…) public class Lab 01 { public static void main(String[ ] args)

String Concatenation (cont…) public class Lab 01 { public static void main(String[ ] args) { Lab 01 lab = new Lab 01(); lab. output(); } public void output() { System. out. println(1 + 2 + “Hello World”); } } Lab 01 -65

Java Object Oriented Programming How Does String Concatenation Work?

Java Object Oriented Programming How Does String Concatenation Work?

The + Symbol • The plus symbol is an overloaded operator. 3 + 4

The + Symbol • The plus symbol is an overloaded operator. 3 + 4 is addition and results in 7 3 + “ 7” is string concatenation and results in “ 37” Lab 01 -67

String Concatenation Here is a typical print statement. System. out. print(“Hello ” + 1

String Concatenation Here is a typical print statement. System. out. print(“Hello ” + 1 + 2); Lab 01 -68

String Concatenation (cont…) System. out. print(“Hello ” + 1 + 2); “Hello 1” Lab

String Concatenation (cont…) System. out. print(“Hello ” + 1 + 2); “Hello 1” Lab 01 -69

String Concatenation (cont…) System. out. print(“Hello ” + 1 + 2); “Hello 1” “Hello

String Concatenation (cont…) System. out. print(“Hello ” + 1 + 2); “Hello 1” “Hello 12” Lab 01 -70

String Concatenation (cont…) Here is another typical print statement. System. out. print(1 + 2

String Concatenation (cont…) Here is another typical print statement. System. out. print(1 + 2 + “ Hello”); Lab 01 -71

String Concatenation (cont…) System. out. print(1 + 2 + “ Hello”); 3 Lab 01

String Concatenation (cont…) System. out. print(1 + 2 + “ Hello”); 3 Lab 01 -72

String Concatenation (cont…) System. out. print(1 + 2 + “ Hello”); 3 “ 3

String Concatenation (cont…) System. out. print(1 + 2 + “ Hello”); 3 “ 3 Hello” Lab 01 -73

String Concatenation (cont…) Here is another typical print statement. System. out. print(“Hello ” +

String Concatenation (cont…) Here is another typical print statement. System. out. print(“Hello ” + 3 * 2); Lab 01 -74

String Concatenation (cont…) System. out. print(“Hello ” + 3 * 2); Multiplication has a

String Concatenation (cont…) System. out. print(“Hello ” + 3 * 2); Multiplication has a higher precedence than addition! Lab 01 -75

String Concatenation (cont…) System. out. print(“Hello ” + 3 * 2); 6 Lab 01

String Concatenation (cont…) System. out. print(“Hello ” + 3 * 2); 6 Lab 01 -76

Sequential Programming (cont…) System. out. print(“Hello ” + 3 * 2); 6 “Hello 6”

Sequential Programming (cont…) System. out. print(“Hello ” + 3 * 2); 6 “Hello 6” Lab 01 -77

String Concatenation (cont…) Here is another typical print statement. System. out. print(“Hello ” +

String Concatenation (cont…) Here is another typical print statement. System. out. print(“Hello ” + 6 - 4); Lab 01 -78

String Concatenation (cont…) System. out. print(“Hello ” + 6 - 4); “Hello 6” Lab

String Concatenation (cont…) System. out. print(“Hello ” + 6 - 4); “Hello 6” Lab 01 -79

String Concatenation (cont…) System. out. print(“Hello ” + 6 - 4); “Hello 6” Compile

String Concatenation (cont…) System. out. print(“Hello ” + 6 - 4); “Hello 6” Compile Time Error “operator - can not be applied to String, int” Lab 01 -80

String Concatenation (cont…) How can we “fix” this problem? System. out. print(“Hello ” +

String Concatenation (cont…) How can we “fix” this problem? System. out. print(“Hello ” + 6 - 4); Lab 01 -81

String Concatenation (cont…) Use parantheses! System. out. print(“Hello ” + (6 - 4)); Lab

String Concatenation (cont…) Use parantheses! System. out. print(“Hello ” + (6 - 4)); Lab 01 -82

String Concatenation (cont…) System. out. print(“Hello ” + (6 - 4)); 2 Lab 01

String Concatenation (cont…) System. out. print(“Hello ” + (6 - 4)); 2 Lab 01 -83

String Concatenation (cont…) System. out. print(“Hello ” + (6 - 4)); 2 “Hello 2”

String Concatenation (cont…) System. out. print(“Hello ” + (6 - 4)); 2 “Hello 2” Lab 01 -84

Java Object Oriented Programming How The Program Runs

Java Object Oriented Programming How The Program Runs

How The Program Runs public class Lab 01 { public static void main(String[ ]

How The Program Runs public class Lab 01 { public static void main(String[ ] args) { Lab 01 lab = new Lab 01(); lab. output(); } public void output() { System. out. println(1 + 2 + “Hello World”); } } Lab 01 -86

How The Program Runs (cont…) public class Lab 01 { public static void main(String[

How The Program Runs (cont…) public class Lab 01 { public static void main(String[ ] args) { Lab 01 lab = new Lab 01(); lab. output(); } public void output() { System. out. println(1 + 2 + “Hello World”); } } Lab 01 -87

How The Program Runs (cont…) public class Lab 01 { public static void main(String[

How The Program Runs (cont…) public class Lab 01 { public static void main(String[ ] args) { Lab 01 lab = new Lab 01(); lab. output(); } public void output() { System. out. println(1 + 2 + “Hello World”); } } Lab 01 -88

How The Program Runs (cont…) public class Lab 01 { public static void main(String[

How The Program Runs (cont…) public class Lab 01 { public static void main(String[ ] args) { Lab 01 lab = new Lab 01(); lab. output(); } public void output() { System. out. println(1 + 2 + “Hello World”); } } Lab 01 -89

How The Program Runs (cont…) public class Lab 01 { public static void main(String[

How The Program Runs (cont…) public class Lab 01 { public static void main(String[ ] args) { Lab 01 lab = new Lab 01(); lab. output(); } public void output() { System. out. println(1 + 2 + “Hello World”); } } Lab 01 -90

How The Program Runs (cont…) public class Lab 01 { public static void main(String[

How The Program Runs (cont…) public class Lab 01 { public static void main(String[ ] args) { Lab 01 lab = new Lab 01(); lab. output(); } public void output() { System. out. println(1 + 2 + “Hello World”); } } Lab 01 -91

How The Program Runs (cont…) public class Lab 01 { public static void main(String[

How The Program Runs (cont…) public class Lab 01 { public static void main(String[ ] args) { Lab 01 lab = new Lab 01(); lab. output(); } public void output() { System. out. println(1 + 2 + “Hello World”); } } Lab 01 -92

How The Program Runs (cont…) public class Lab 01 { public static void main(String[

How The Program Runs (cont…) public class Lab 01 { public static void main(String[ ] args) { Lab 01 lab = new Lab 01(); lab. output(); } public void output() { System. out. println(1 + 2 + “Hello World”); } } Lab 01 -93

Java Object Oriented Programming Control Structures

Java Object Oriented Programming Control Structures

Control Structures Refers to the order in which the individual statements of a program

Control Structures Refers to the order in which the individual statements of a program are executed or evaluated Lab 01 -95

Control Structures (cont…) • • Sequential (Default) Branching (Method Calls) Conditional (if and switch)

Control Structures (cont…) • • Sequential (Default) Branching (Method Calls) Conditional (if and switch) Repetition (while & for loops) Lab 01 -96

Sequential Control: Statements are executed in the order in which they are written. Lab

Sequential Control: Statements are executed in the order in which they are written. Lab 01 -97

Sequential Control (cont…) System. out. println(“ABC”); System. out. println(“DEF”); Lab 01 -98

Sequential Control (cont…) System. out. println(“ABC”); System. out. println(“DEF”); Lab 01 -98

Sequential Control (cont…) System. out. println(“ABC”); System. out. println(“DEF”); Output: ABC DEF Lab 01

Sequential Control (cont…) System. out. println(“ABC”); System. out. println(“DEF”); Output: ABC DEF Lab 01 -99

Branching (cont…) Branching: Allows the flow of execution to jump to a different part

Branching (cont…) Branching: Allows the flow of execution to jump to a different part of the program. Lab 01 -100

Branching (cont…) public static void main(String[] args) { Lab 01 lab = new Lab

Branching (cont…) public static void main(String[] args) { Lab 01 lab = new Lab 01(); lab. output(); } public void output() { System. out. println(“Hello World”); } Lab 01 -101

Branching (cont…) public void method. A() { method. B(); method. C(); } public void

Branching (cont…) public void method. A() { method. B(); method. C(); } public void method. B() { System. out. print(“Hello ”); } public void method. C() { System. out. print(“World”); } Lab 01 -102

Begin Every Program with Your Name in the form of a Remark Statement //

Begin Every Program with Your Name in the form of a Remark Statement // John Spicer public class Lab 01 A { } Lab 01 -103

Java Object Oriented Programming Questions?

Java Object Oriented Programming Questions?

Java Object Oriented Programming Begin Lab 01

Java Object Oriented Programming Begin Lab 01