by EYAD N.

Remember in array

This if you still don't know the values

double[] the_salaries = …… double[5];

the_salaries[0] = 50000.0; // Assigning a value to the first element

the_salaries[1] = 60000.0; // Assigning a value to the second element

this if you know the values

double[] numbers = {10, 20, 30, 40, 50};

new

Application on Functions Overloading

what will be the output of this code

public class main {

static int day;

public static void main(String[] args) {

int a=10 ,b= 20;

char x='A', y='a';

System.out.println(larger(a, b));

System.out.println(larger(x,y));

}

public static int larger (int n1 ,int n2)

{

if ( n1 > n2 ) return n1 ;

else return n2;

}

public static char larger (char c1, char c2)

{

if (c1>c2) return c1;

else return c2;

}

Explnation

In this code, you have two larger() methods:

One that takes two integers and returns the larger integer
Another that takes two characters and returns the lexicographically larger character

When you call larger(), Java determines which method to invoke based on the argument types:

For larger(10, 20), it uses the integer method (Function)
For larger('A', 'a'), it uses the character method (Function)

The compiler determines which method to call based on the arguments passed

NOTES

https://youtu.be/n5pcp_WOMWY?si=wFL3cvDCF2HnrVhg

what will be the output of in this code

Scanner scan = new Scanner(System.in);

int i;

double Y=0;

for (i=0; i<5;i++)

{

System.out.println("Enter Salary For Employee No" + (i+1));

Y= scan.nextDouble();

}

System.out.println(Y);

if user enter in first case 2 and second case 3 and third case 4 and fourth case7 and fifth case 9

will be 9 because in this specific code, there's a logical issue: the Y variable will only store the last employee's salary, not all salaries. If you want to store multiple salaries, you should use an array instead of a single variable.

The corrected version:

double[] salaries = new double[5];

for (int i=0; i<5; i++) {

System.out.println("Enter Salary For Employee No" + (i+1));

salaries[i] = scan.nextDouble();

}

make this but by Enhanced For Loop

int x [] = {10,20,30};

for(int i=0;i<x.length;i++){

System.out.println(x[i]);

int x [] = {10,20,30};

for(int s : x) {

System.out.println(s);

}

Explnation

https://youtu.be/_2n7Q4uKAEM?si=TZOtsLP75pktxEzh

make a grade classification program ,It takes a single character input (representing a grade, e.g., A, B, C, etc.), processes the input using a switch statement, and outputs a corresponding message describing the grade's quality.

import java.util.Scanner;

public class main {

public static void main(String[] args) {

char grade;

System.out.println("Enter Your Grade");

Scanner scan = new Scanner(System.in);

grade = scan.next().charAt(0);

switch (grade)

{

case 'A' :

System.out.println("Excellent");

break;

case 'B':

System.out.println("Very Good");

break;

case 'C':

System.out.println("Good");

break;

case 'D':

case 'E':

System.out.println("Fair");

break;

default : System.out.println("Invalid one, pleasechooseanother one");

}

//case E is false we add it only for learn the concept

}}

Remember very important

instead of make this : char grade = scan.nextchar();

make this

……….

char grade;

grade = scan.next().charAt(0);

the diffrence between ‘‘ and ““

Single quotes =….. , Double quotes = ……

character

string

case “eyad”:

System.out.println("Monday");

break;

………………..

case ‘A‘:

System.out.println("Monday");

break;

double Y; // Y is …. but not …..

double Y = 0; // Y is … and ……

declared

initialized

declared

initialized

Make a program say if the number is even or odd

Note : why we can not just type = instead of == in this code

Ans

Using = in a conditional statement like if (n % 2 = 0) is not valid, as it will always evaluate to true because the expression n % 2 = 0 is an assignment that assigns the value 0 to n % 2, which is then interpreted as a boolean value of true.

Instead, you should use the comparison operator == to check if the remainder of n divided by 2 is equal to 0 (for even numbers) or 1 (for odd numbers).

Remember (very important)

we can use {} in if to define the code block that should be executed for each condition and make it more readable

int x = 5;

if (x > 0) {

System.out.println("Positive");

x = x - 1; }

System.out.print(x);

the output is

Positive

Attempting to use a ….. statement with a double or float will result in a compile-time error.

switch

// This will cause a COMPILE-TIME ERROR

double price = 10.5;

switch(price){

// Cannot use double in switch

case 10.0:

System.out.println("Exact match");

break;

}

correct the following java code

Scanner scan = new Scanner(System.in);

char grade = scan.nextchar();

Scanner scan = new Scanner(System.in);

char grade = scan.next().charAt(0);

Explanation

If the user enters multiple characters like "ABC", next().charAt(0) will only take the first character 'A'

If the user enters multiple characters like "ABC", next().charAt(1) will only take the first character 'B'

Dividing a double by a double gives a ….

System.out.println(1.0 / 2.0); // 0.5

2. Dividing a float by a float gives a

System.out.println(1.0f / 2.0f); // 0.5

double
float

type the image

System.out.println("Work days Are \n Sunday \t Monday \t Tuesday \t Wendsday \t");

@\t is tape

Another example

int x = 1;

System.out.println("Hello" + "\t" + x);

//Hello 1

Don't forget this👆👆

what is the outout of this code

for (int i=0; i<10;i++)

{

System.out.print("E");

}

for (int i=0; i<10;i++)

{

System.out.println("E"+ i);

}

Note

for(int x=1;x<=10;++x);

in prevous sentence its ; not ,

EEEEEEEEEE
E0
E1
E2
E3
E4
E5
E6
E7
E8
E9

Note

the output of the next two images

Hello1

Hello2

Hello3

Hello4

Hello5

what is the 17&5?

2 (the reminder is 2)

First find how many times 5 goes into 17 evenly:

17 ÷ 5 = 3.4

We take only the whole number part: 3

Then multiply that whole number (3) by the divisor (5):

3 × 5 = 15

Finally, subtract that result from the original number to get the remainder:

17 - 15 = 2

This 2 is your remainder/modulus

Remember

%(Modulus) Returns the division remainder

THE DECREMENT OPERATOR is like INCREMENT but Used to decrease the value of a variable by ….

decrement operator: --

THE DECREMENT OPERATOR is like INCREMENT but Used to decrease the value of a variable by 1

decrement operator: --

tell me the output of this code

System.out.println("The sum is " + (1 + 3) );
System.out.println("The sum is + 1 + 3 );

The sum is 4
The sum is 13

i++ VS ++1

++i increments the value of i by 1 and uses the new value in the statement
i++ increments the value of i by 1 and uses the original value in the statement
Test Your self
In the two images

The answer 👆👆

int i1 = 2;

i1 *= 5 + 1;

→ Equivalent to:

….

→ Not to:

….

i1 = il* (5 + 1) // 12

i1 = il * 5 + 1 // 11

Logical AND operator: &&

Logical OR operator: ||

Logical NOT operator: !

Test you self

the x in the image is true or false?

True

Example of and

int a=200, b=33, c=500;

if (a>b && c>a)

System.out.println("C is the greatest number");

}}

corect the following sentence int x = 12383402047527075;

long x = 12383402047527075L; we choose it because it from -9223372036854775808 to 9223372036854775807 but int from -2147483648 to 2147483647

Intl

make a program calculate the Area of a Circle

System.out.println("What is the redius");

Scanner scan = new Scanner(System.in);

//this is extension that we added that scan and we make it scan the keyboard which what will user type

double redius = scan.nextDouble();

if (redius>0) {

System.out.println("Area of square is"+ 3.14*redius*redius); }

OR

System.out.println("Area of square is"+ 3.14* Math.pow(radius, 2));

type 3.14 with to ways with initialization

float X = 3.14f;

System .out.println(X);

double y = 3.14;

// it's without f

🟥🟥

fractional number up to 6-7 digits

ex. 3.141592f

fractional number up to 15 digits

ex. 3.141592653589793

boolean is either ....or....

true or false EX double y = 3.14; boolean z = true; System.out.println(z); the console will be : true

what is the difference in

int x = 123;

System.out.println(x);

AND

int x = 123;

System.out.println("x");

first output will be x

the second outpot will be 123

tell me each one in the image

source code

compiler

byte code

jvm (which it subset from jdk which is Java Development Kit

machine code

{}
()
/ (its a division)

curly braces
parentheses
forward slash

while loop

what will be the output

int count = 1;

while (count<=5) { //[

System.out.println("Hi");

++count;

}

Make the output in 3 ways

eyad

yasser

System.out.println("eyad"); System.out.println("yasser");
System.out.print("eyad\n"); System.out.print("yasser\n");
System.out.println("eyad\nyasser");

string is alot of....

char (@is line of words)

tell me each one

int x = 123; is called ........

make this my number is : 123 with initialization

initialization
int x = 123;
System.out.println("my number is " + x);

A …..: is a self-contained block of statements that perform a specific task.

Functions - Methods

Methods or functions

Correct the follwing code

public class main {

public static void main(String[] args) {

System.out.println("eyad");

System.out.print( 5+sum(2,10)) ;

////////////////

public static void sum(int x1, int x2)

{

int result=0;

result= x1+x2;

}

what will be the output of this code
System.out.println("eyad");
drawline('*' ,10);
System.out.println("yasser");
drawline('E',30);
}
////////////////
public static void drawline(char line, int length)
{
for (int i=0; i<length;i++)
{
System.out.print(line);
}
System.out.println();
}

public class main {
public static void main(String[] args) {
System.out.println("eyad");
System.out.print( 5+sum(2,10)) ;
}
////////////////
public static int sum (int x1, int x2)
{
int result=0;
result= x1+x2;
return result;
}
}

the output of the prevous code is
eyad
12
eyad
**********
yasser
EEEEEEEEEEEEEEEEEEEEEEEEEEEEEE

Rmember this if you know the vakue(s) of input(s)

public class main {

public static void main(String[] args) {

System.out.println("eyad");

drawline();

System.out.println("yasser");

drawline();

}

////////////////

public static void drawline()

{

for (int i=0; i<10;i++)

{

System.out.print("E");

}

System.out.println();

}

Local Variables

where is the error in this code
{
int sum =10;
}
System.out.println(sum);
what will be the output?
public class main {
static int sum=10;
// called Global variable
public static void main(String[] args) {
{
int sum =12;
System.out.println(sum);
}
}}
what will be the output?
public class main {
static int sum=10;
public static void main(String[] args) {
{
int sum =12;
System.out.println(main.sum);
}
}}

{
int sum =10;
}
// this is called block
System.out.println(sum);

The error in your code arises because the variable sum is declared inside the block of the curly braces {} and is therefore out of scope when you attempt to access it in the System.out.println(sum) statement. Variables declared inside a block are only accessible within that block

12
EX

EX
If the line int sum = 12; were removed, the output would be 10, because the System.out.println(sum); would then refer to the class-level static sum.
10
Explnation
put the name of class before the name of variable to print global variable not the local variable

passing array to function

For Remembring only

`public class main {`

public static void main(String[] args) {

// Creating an array

int[] numbers = {10, 20, 30, 40, 50};

// Passing array to function

int totalSum = calculateSum(numbers);

// Printing result

System.out.println("Total Sum: " + totalSum);

}

// Method to calculate sum of array elements

public static int calculateSum(int[] arr) {

int sum = 0;

for (int i = 0; i < arr.length; i++) {

sum += arr[i];

}

return sum;

}}

invoke=….

Call or mention

➤ …… is a style of programming, a way of thinking about software construction.

A programming paradigm

ex for procedural (a type in Paradigms)

Remember this

class

object

attrbute

Scanner scan = new Scanner(System.in);

Scanner is class (the data type of the object ) and we take from it object to can adjust it and we name it scan

we type new to make place in ram for it

Folder 1

package eyad;

package eyad;

public class main {

public static void main(String[] args) {

Book myBook = new Book();

myBook.displayBookInfo(" OOP java", "eyad", "9780446310789");

System.out.println("-------------------------");

Book myBook2 = new Book();

myBook2.title="OOP java";

myBook2.author="eyad";

myBook2.isbn="9780446310789";

myBook2.text();

}}

}}

Folder 2

package eyad;

public class Book {

String title;

String author;

String isbn;

public void displayBookInfo(String title, String author, String isbn) {

System.out.println("Book Details:");

System.out.println("Title: " + title);

System.out.println("Author: " + author);

System.out.println("ISBN: " + isbn);

}

public void text () {

System.out.println("Book Details:");

System.out.println("logo: " + title);

System.out.println("name: " + author);

System.out.println("id: " + isbn);

}}

THE OUTPUT WILL BE

Book Details:

Title: OOP java

Author: eyad

ISBN: 9780446310789

-------------------------

Book Details:

logo: OOP java

name: eyad

id: 9780446310789

——————————————————————————————————————

folder 1

package eyad;

public class main {

public static void main(String[] args) {

Book myBook = new Book(" OOP java", "eyad", "9780446310789");

myBook.author="eyad";

myBook.displayBookInfo();

}}

folder 2

package eyad;

public class Book {

// Instance variables (attributes) of the Book

String title;

String author;

String isbn;

// Constructor to initialize the Book object

public Book(String title, String author, String isbn) {

this.title = title;

this.author = author;

this.isbn = isbn;

}

// Method to display book information

public void displayBookInfo() {

System.out.println("Book Details:");

System.out.println("Title: " + title);

System.out.println("Author: " + author);

System.out.println("ISBN: " + isbn);

}}

THE OUTPUT WILL BE

Book Details:

Title: OOP java

Author: eyad

ISBN: 9780446310789

question 1

what will be the output of this

folder 1

package eyad;

public class main {

public static void main(String[] args) {

Book myBook = new Book(" OOP java", "eyad", "9780446310789");

myBook.displayBookInfo(" OOP C++", "yasser", "9780446310789");

}}

folder 2

package eyad;

public class Book {

// Instance variables (attributes) of the Book

String title;

String author;

String isbn;

// Constructor to initialize the Book object

public Book(String title, String author, String isbn) {

this.title = title;

this.author = author;

this.isbn = isbn;

}

// Method to display book information

public void displayBookInfo(String title, String author, String isbn) {

System.out.println("Book Details:");

System.out.println("Title: " + title);

System.out.println("Author: " + author);

System.out.println("ISBN: " + isbn);

}}

question 2

what will be the output of this

folder 1

package eyad;

public class main {

public static void main(String[] args) {

Book myBook = new Book();

myBook.author="eyad";

myBook.displayBookInfo();

}}

folder 2

package eyad;

public class Book {

// Instance variables (attributes) of theBook

String title;

String author;

String isbn;

// Method to display book information

public void displayBookInfo() {

System.out.println("Book Details:");

System.out.println("Title: " + title);

System.out.println("Author: " + author);

System.out.println("ISBN: " + isbn);

}}

Book Details:

Title: OOP C++

Author: yasser

ISBN: 9780446310789

Book Details:
Title: null
Author: eyad
ISBN: null

this concept is called …..

Encapsulation

main folder

why there is an error in title?

Book myBook2 = new Book();

myBook2.title="OOP java";

myBook2.author="eyad";

myBook2.text();

class folder

private String title = "oop c++";

public String author;

public void text () {

System.out.println("Book Details:");

System.out.println("logo: " + title);

System.out.println("name: " + author);

}

make set function to adjust (set) the title to become oop java
make get function to get the name of the title

Bec. title attribute is private

Explnation

Visibility: The private modifier restricts the access to the member (e.g., a variable or method) to within the same class only.

Visibility: The public modifier allows the member to be accessible from any other class in the program, provided the class itself is accessible.

public void set_title(String title ) {
this.title=title;
}
public void get_title() {
System.out.println(title) ;
}
The main folder after make set and get
public class main {
public static void main(String[] args) {
Book myBook2 = new Book();
myBook2.author="eyad";
myBook2.set_title("oop java");
myBook2.get_title() ;
myBook2.text();
}}

The output after make set and get

oop java

Book Details:

logo: oop java

name: eyad

Which of the following code snippets will result in a compilation error in Java due to improper use of inheritance?

Explnation of inheritance

// Parent class

class Animal {

void eat() {

System.out.println("This animal eats food.");

}

// Child class

class Dog extends Animal {

void bark() {

System.out.println("The dog barks.");

}

// Using inheritance

public class Main {

public static void main(String[] args) {

Dog dog = new Dog();

dog.eat(); // Inherited from Animal

dog.bark(); // Defined in Dog

}

class Person {

void speak() {

System.out.println("A person speaks in general.");

}

class Boy extends Person {

@Override // we can delete it

void speak() {

super.speak(); // Call the parent class method

System.out.println("The boy adds: 'Hey, I'm a boy!'");

}

class Girl extends Person {

@Override // we can delete it

void speak() {

super.speak(); // Call the parent class method

System.out.println("The girl adds: 'Hi, I'm a girl!'");

}

public class Main {

public static void main(String[] args) {

Girl girl1 = new Girl();

girl1.speak();

}

What will be the output of the following code?

Girl girl1 = new Girl();

girl1.speak();

Join Course

Preview

Author

EYAD N.

Information

Last changed
a day ago

Report course

java

Remember in array

Application on Functions Overloading

make this but by Enhanced For Loop

Explnation

Remember very important

Explanation

Don't forget this👆👆

what is the outout of this code

i++ VS ++1

Example of and

while loop

Methods or functions

Rmember this if you know the vakue(s) of input(s)

Local Variables

passing array to function

For Remembring only

public class main {

Folder 1

Folder 2

THE OUTPUT WILL BE

folder 1

folder 2

THE OUTPUT WILL BE

question 1

what will be the output of this

folder 1

folder 2

question 2

what will be the output of this

folder 1

folder 2

this concept is called …..

Encapsulation

main folder

class folder

Explnation

The main folder after make set and get

The output after make set and get

Which of the following code snippets will result in a compilation error in Java due to improper use of inheritance?

Explnation of inheritance

What will be the output of the following code?

Author

EYAD N.

Information

`public class main {`