Java Control Structure Session 1 Complete (1).pptx

Java
Programming
Dr. Meenu & Dr. Riman Mandal & Shamim
Ahmad
Faculty
School of Engineering & Technology (SOET)
K. R. Managalam University
Java Control Structure
Dr. Meenu & Dr. Riman Mandal & Shamim Java Programming Java Control Structure 1/67

Session Agenda
Session
1
Java Control Structure -
Decision Making
if, if-else,
if-else-ifladder
The switch-case
Statement
Practical
Scenarios Q&A
Session
2
Java Control Structure -
Looping
for, while,
do-while
Jump Statements -
break, continue
Practical
Scenarios Q&A

Key Learning Outcome
Gain a comprehensive understanding of
Java’s control flow statements.
Learn how to use conditional statements
for decision-making.
Discover the use cases for different
variations of loop structures.
Utilize jump statements to alter control flow
within loops.
Apply control structures in real-world
programming problem-solving.

Session 1
Session 1 emphasizes on Decision Making in
Java

Importance of Control Structures
Control structures are the cornerstone of
programming logic.

Importance of Control
Structures
They Provide the ability
to Make
Decisions
Repeat Tasks
Control Flow

to Make Decisions
Execute code blocks selectively based on
conditions.
Repeat
Tasks
Control Flow

to Make
Decisions
Repeat Tasks
Automate code execution to process data
eﬀiciently.
Control Flow

to Make
Decisions
Repeat Tasks
Control Flow
Break out of loops, skip iterations, and create
complex logic paths.

Decision Makings
Conditional Skip/Jump - if

Decision Makings
Two-way Branch - if-else

Decision Makings
Hirerchical Decision - nested
if

Decision Makings
Hirerchical Decision - nested
if
Multiway Branch - if-else-ifladder,
switch-case

Conditional Skip/Jump
Use of ifStatement
You need to execute a code block only if a
single condition is true.

Use of ifStatement
Synta
x
if (<binary_condition>){
//Statement 1
//Statement 2
.
.
.
//Statements if condition is true.
}

Use of ifStatement
Exampl
e
Excercis
e
int age = 25;
if (age >= 18) {
System.out.println("You are eligible to vote.");
} [Complete]
WAP that inputs a number (N) and adds 5 to N if
N is odd then print it.
[Solution
]

Two-way Branch
Use of if-elseStatement
You have two distinct code blocks – one to execute if
a condition is true, and another to execute if the
condition is false.

Two-way Branch
Synta
x
if (<binary_condition>){
.
.
.
//Statements if condition is true.
} else{
.
.
.
//Statements if condition is false.
}

Two-way Branch
Exampl
e
int number = 25;
if (number % 2 == 0){ System.out.println(number + "
is even.");
} else{
System.out.println(number + " is even.");
} [Complete
]

Two-way Branch: Excercise
WAP to find the maximum among two numbers.
[Solution
]
WAP that inputs a number (N) and adds 7 to N if N is odd,
else add 4.
[Solution
]
WAP to create a simple number gussing game. First set a
secrect number and ask user to provide a input. If the
input matches to secrect number user wins, for mismatch
user loses. [Solution]

Nesting
Use of Nested if-elseStatements
You need to check multiple conditions in a
dependent manner. The inner ’if’ statements are
only evaluated if the outer ’if’ conditions are true.

Nesting
Synta
x
if (<binary_condition1>){
//Statements if condition1 is true. [if
(<binary_condition2>){
//Statements if condition1 and condition2 is true.
} else{
//Statements if condition1 is true and condition2 is false.
}]
} else{
//Statements if condition1 is false. [if
(<binary_condition3>){
//Statements if condition1 is false and condition3 is true.
} else{
//Statements if condition1 and condition3 is false.
}]
}
Anything enclosed in […] means optional

Nesting
Example
1
int age = 23;
boolean hasLicense = true; if
(age >= 18) {
if (hasLicense) {
System.out.println("You are eligible to vote and drive.");
} else {
System.out.println("You are eligible to vote but cannot drive.");
}
} else {
System.out.println("You are not eligible to vote or drive.");
} [Complete]

Nesting
Example 2: Find maximum amoung three
numbers
if(a>b)
if (a>c)
printf(“A is max.”); else
printf(“C is max.”);
else
if (b>c)
printf(“B is max.”); else
printf(“C is max.”);
[Complete]
Use your creativity and desing alternative
solutions to solve the same problem.
For single statment within a block {…} is not mandatory

Nesting: Excercise
WAP that determines whether a given year is a leap year or not. A
year is a leap year if it is divisible by 4 but not divisible by 100, or if it
is divisible by 400.
WAP that calculates the discount percentage for a customer’s
purchase based on the purchase amount and customer loyalty. If the
purchase amount is greater than 100 and the customer has been loyal
(member for more than a year), they get a 10% discount; otherwise,
they get a 5

Multi-way Branching
Use of if-else-iflader Statements
You need to check a sequence of multiple conditions
and execute the first block whose condition is
true.

Multi-way Branching
Synta
x if (condition1) {
// Code block 1
} else if (condition2) {
// Code block 2
} else if (condition3) {
// Code block 3
}
...
else {
// Default code block
}

Multi-way Branching
Example 1: Grade
Claculation
int marks = 67;
if(marks >= 90)
printf(“Grade = A+”); else
if (marks >= 80)
printf(“Grade = A”);
else if (marks >= 70)
printf(“Grade = B”);
else if (marks >= 60)
printf(“Grade = C”); else
if (marks >= 40)
printf(“Grade = D”);
else
printf(“Grade = Fail”);

Multi-way Branching
Example 2: Categorizing
Temperatures
double temperature = 12;
if (temperature < 0) {
System.out.println("Freezing");
} else if (temperature >= 0 && temperature < 15) {
System.out.println("Cold");
System.out.println("Mild");
System.out.println("Warm");
} else {
System.out.println("Hot");
}

Multi-way Branching
Example 3: Day of the
Week int dayNumber = 3;
if (dayNumber == 1) {
System.out.println("Monday");
} else if (dayNumber == 2) {
System.out.println("Tuesday");
System.out.println("Wednesday");
System.out.println("Thursday");
}
...
else {
System.out.println("Invalid day number");
}

Multi-way Branching: Code It
Yourself
Solution to Quadratic equation: Ax2 + Bx+ C = 0
1. Start
2. Input A, B, C.
3. If A=0 then print “This is not a quadratic equation” and stop.
4. D = B^2 - 4AC
5. L = -B / 2A
6. If D<0 then print “No real root found.” and stop.
7. Else If D=0 then print Only one root: L and stop.
8. Else
9. X1 = L + (√D/2A)
10. X2 = L - (√D/2A)
11. Print Root1 = X1 and Root2 = X2
12. stop

Brainstorming Session: Fill in the
Blanks
if, if-else, if-else-ifladder, nested if
1 The statement is used to execute a code block ifa condition is
true.
2 The statement is used to execute a different code block ifthe
original condition is false.
3 To test multiple conditions sequentially, you would use the
construct.
4 The elsestatement associated with a nested if statement is
executed only when of the preceding ifconditions are true.
5 In an if-else ladder, if the condition specified in the if statement
evaluates to true, the corresponding block of code is executed, and
the control then exits to the of the ladder.

Blanks
if, if-else, if-else-ifladder, nested if
1 The if statement is used to execute a code block ifa condition is
true.
2 The else statement is used to execute a different code block if
the original condition is false.
3 To test multiple conditions sequentially, you would use the
if-else-if ladder construct.
4 The elsestatement associated with a nested if statement is
executed only when none of the preceding ifconditions are true.
5 In an if-else ladder, if the condition specified in the if statement
evaluates to true, the corresponding block of code is executed, and
the control then exits to the end of the ladder.

Multi-way Branching: Excercise I
WAP that calculates a person’s Body Mass Index (BMI) based on
their height (in meters) and weight (in kilograms) inputs. Then,
classify the BMI into categories according to the following criteria:
Underweight: BMI less than
18.5 Normal weight: BMI 18.5
to 24.9
Overweight: BMI 25 to 29.9
Obesity: BMI 30 or greater
Hint : BMI = weight(kg)/height(m)2
WAP that converts temperature from Celsius to Fahrenheit and
vice versa. The program should prompt the user to choose the
conversion direction and input the temperature accordingly.
Nested if statements can be used to handle the conversion logic.

Multi-way Branching: Excercise II
Create a program that takes three sides of a triangle as input and
determines whether the triangle is equilateral, isosceles, or scalene.
Here are the definitions:
Equilateral triangle: All three sides are equal in
length. Isosceles triangle: Two sides are equal in
length.
Scalene triangle: All three sides have different lengths.
WAP that calculates the price of a movie ticket based on the age of
the customer and the time of the show. The ticket prices are as
follows: Children (age <= 12): Rs. 5 before 6 PM, Rs. 8 after 6 PM
Adults (age > 12 and age <= 65): Rs. 10 before 6 PM, Rs. 12 after 6
PM
Seniors (age > 65): Rs. 8 for all show times.

Multi-way Branching: Excercise III
WAP that calculates the total price for items in an online shopping
cart. Apply discounts based on the total purchase amount as follows:
10% discount for purchases above Rs. 100 but less than Rs.
200. 15% discount for purchases above Rs. 200 but less than
Rs. 500. 20% discount for purchases of Rs. 500 or more.
WAP to compute the electric bill based on the specifications provided
in your household electricity bill. The bill includes both fixed charges
and variable charges, with the variable charges dependent on the
number of units consumed.

Multi-way Branching: Excercise I
WAP that calculates a person’s Body Mass Index (BMI) based on
their height (in meters) and weight (in kilograms) inputs. Then,
classify the BMI into categories according to the following criteria:
Underweight: BMI less than
18.5 Normal weight: BMI 18.5
to 24.9
Overweight: BMI 25 to 29.9
Obesity: BMI 30 or greater
Hint : BMI = weight(kg)/height(m)2
WAP that converts temperature from Celsius to Fahrenheit and
vice versa. The program should prompt the user to choose the
conversion direction and input the temperature accordingly.
Nested if statements can be used to handle the conversion logic.

Multi-way Branching: Excercise II
Create a program that takes three sides of a triangle as input and
determines whether the triangle is equilateral, isosceles, or scalene.
Here are the definitions:
Equilateral triangle: All three sides are equal in
length. Isosceles triangle: Two sides are equal in
length.
Scalene triangle: All three sides have different lengths.
WAP that calculates the price of a movie ticket based on the age of
the customer and the time of the show. The ticket prices are as
follows: Children (age <= 12): Rs. 5 before 6 PM, Rs. 8 after 6 PM
Adults (age > 12 and age <= 65): Rs. 10 before 6 PM, Rs. 12 after 6
PM
Seniors (age > 65): Rs. 8 for all show times.

Multi-way Branching: Excercise III
WAP that calculates the total price for items in an online shopping
cart. Apply discounts based on the total purchase amount as follows:
10% discount for purchases above Rs. 100 but less than Rs.
200. 15% discount for purchases above Rs. 200 but less than
Rs. 500. 20% discount for purchases of Rs. 500 or more.
WAP to compute the electric bill based on the specifications provided
in your household electricity bill. The bill includes both fixed charges
and variable charges, with the variable charges dependent on the
number of units consumed.

Predict the output (if-else) I
Brainstorming Session Continues . . .
Snipet
1
int x = 10; if (x
> 5) {
if (x < 15) {
System.out.println("x is between 5 and 15");
} else {
System.out.println("x is greater than or equal to 15");
}
} else {
System.out.println("x is less than or equal to 5");
}

Predict the output (if-else) II
Snipet
2
int age = 20;
if (age >= 18) {
System.out.println("You are an adult.");
} else if (age >= 13) { System.out.println("You are a
teenager.");
} else {
System.out.println("You are a child.");
}

Predict the output (if-else) III
Snipet
3
int num = 7;
if (num % 2 == 0) {
System.out.println("Even");
} else if (num % 3 == 0) {
System.out.println("Divisible by 3 but not even");
} else {
System.out.println("Not even or divisible by 3");
}

Predict the output (if-else) IV
Snipet
4
int a = 10, b = 20, c = 30; if (a >
b && a > c) {
System.out.println("a is the largest number.");
} else if (b > a && b > c) {
System.out.println("b is the largest number.");
} else {
System.out.println("c is the largest number.");
}

Predict the output (if-else) V
Snipet
5
int num = 10; if
(num > 0) {
if (num % 2 == 0) {
System.out.println("Positive even number.");
} else {
System.out.println("Positive odd number.");
}
} else {
System.out.println("Not a positive number.");
}

Predict the output (if-else) VI
Snipet
6
int marks = 85;
if (marks >= 90) {
System.out.println("Grade A");
} else if (marks >= 80) {
System.out.println("Grade B");
} else if (marks >= 70) {
System.out.println("Grade C");
} else {
System.out.println("Grade D");
}

Predict the output (if-else) VII
Snipet
7
int num = 10; if
(num > 0) {
if (num % 2 == 0) {
System.out.println("Positive even number.");
} else {
System.out.println("Positive odd number.");
}
} else if (num < 0) { System.out.println("Negative
number.");
} else {
System.out.println("Zero.");
}

Predict the output (if-else) VIII
Snipet
8
int num = 5; if
(num > 0) {
if (num < 10) {
System.out.println("Single digit positive number.");
} else {
System.out.println("Positive number, but not single digit."
}
} else {
System.out.println("Non-positive number.");
}

Predict the output (if-else) IX
Snipet
9
int x = 5, y = 10; if (x
> 0) {
if (y > 0) {
System.out.println("Both x and y are positive.");
} else {
System.out.println("x is positive but y is not.");
}
} else {
System.out.println("x is not positive.");
}

Predict the output (if-else) X
Snipet
10
int a = 10, b = 20, c = 30; if (a >
b) {
if (a > c) {
System.out.println("a is the largest number.");
} else {
}
} else {
if (b > c) {
System.out.println("b is the largest number.");
} else {
}
}

Multi-way Branching: switch-case
The switch-casestatement is used to perform
different actions based on the value of a variable
or expression.
It provides a cleaner and more eﬀicient
alternative to long if-else-ifchains when dealing
with multiple options.

switch-caseStatement
Syntax
Synta
x
switch (<control-var>) {
case <value1>:
// code block 1
case <value2>:
// code block 2
case <value3>:
// code block 3
// more cases...
[default:
// default code block]
}
Only supports int,
char, string, enum
data types for control
variable
Does not support
double
data type
Checks only for
equality (==)
execute code block if
control variable
equals(==) case

switch-caseFall Through
is switch-caseincompleted Without breakstatement?
Senari
o
int x = 3;
switch (x) {
case 1:
System.out.print("1"); case
3:
System.out.print("3");
case 5: System.out.print("5");
case 7:
System.out.print("7");
default:
System.out.print("No Match");
}
Outpu
t
The output will be: 357No Match
When control variable
matches with a case value
rest of the cases are ignored
and all the statements are
executed
breakis used to resolve
the problem

switch-casewith breakStatement
Syntax
Synta
x
switch (<control-var>) { case
<value1>:
// code block 1
break;
case <value2>:
// code block 2
break;
case <value3>:
// code block 3
break;
// more cases with break...
[default:
// default code block]
}
When control variable
matches
with a case value only the
statements associated with
the case block is executed.
breakstatement is used to
exit
the switch statement to end
of switch statement.

Example 1
char grade = 'B';
switch (grade) {
case 'A':
System.out.println("Excellent!");
break;
case 'B':
System.out.println("Great job!");
break;
case 'C':
System.out.println("Well done.");
break;
case 'D':
System.out.println("Youpassed.");
break;
case 'F':
System.out.println("Better try again.");
break;
default:
System.out.println("Invalid grade.");
}

Example 2
int choice = 2;
switch (choice) {
case 1:
System.out.println("You ordered a Cappuccino."); break;
case 2:
System.out.println("You ordered an Espresso."); break;
case 3:
System.out.println("You ordered a Latte."); break;
default:
System.out.println("Invalid menu selection.");
}

Menu Driven Programming I
switch-casewith breakStatement: Example 3
using java.util.Scanner;
class TempConversion{
public static void main(String args[]){ Scanner input =
new Scanner (System.in);
System.out.println("Enter 1 for Celsius to Fahrenheit");
System.out.println("Enter 2 for Fahrenheit to Celsius");
System.out.println("Enter your choice: ");
int choice = input.nextInt();
double tempInput, tempOutput;
switch (choice) {
case 1:
System.out.print("Enter Temperature in Celsius: "); tempInput
= input.nextDouble();
tempOutput = (tempInput * 9 / 5) + 32;
System.out.println(tempInput + " oC is equal to "
+ tempOutput + " oF.");
break;

Menu Driven Programming II
switch-casewith breakStatement: Example 3
case 2:
System.out.print("Enter Temperature in Fahrenheit: "); tempInput
= input.nextDouble();
tempOutput = (tempInput - 32) * 5 / 9;
System.out.println(tempInput + " oC is equal to "
+ tempOutput + " oF.");
break;
default:
System.out.println("Invalid menu selection.");
}
}
}

Blanks
switch-case
1 In Java, the switch statement is used to perform different actions
based on the value of a .
2 The default case in a switch statement is executed if none of the
other
match the value of the expression.
3 The break statement in a switch statement is used to exit the
switch block and prevents .
4 If a break statement is omitted in a case block, control will fall
through to the next block.
5 The switch statement is considered an alternative to long
chain
s when dealing with multiple options.
6 The default case in a switch statement is .

Blanks
switch-case
1 In Java, the switch statement is used to perform different actions
based on the value of a control variable .
2 The default case in a switch statement is executed if none of the
other
cases match the value of the expression.
3 The break statement in a switch statement is used to exit the
switch block and prevents fall-through .
4 If a break statement is omitted in a case block, control will fall
through to the next case block.
5 The switch statement is considered an alternative to long if-
else chains when dealing with multiple options.
6 The default case in a switch statement is optional
.

switch-case: Excercise I
Calculator Program: Write a Java program to implement a
simple calculator that performs addition, subtraction,
multiplication, and division based on the user’s choice using a
switch-case statement.
Grade Calculator: Develop a Java program that takes a student’s
score as input and prints out their corresponding grade (A, B, C, D,
F) based on the score using a switch-case statement.
Month Name: Create a Java program that takes an integer
representing a month (1 for January, 2 for February, etc.) as input
and prints out the name of the month using a switch-case statement.
Day of the Week: Write a Java program that takes an integer
representing a day of the week (1 for Monday, 2 for Tuesday, etc.)
as
input and prints out the name of the day using a switch-case
statement.

switch-case: Excercise II
Simple ATM Machine: Develop a Java program to simulate a
simple ATM machine. The program should allow users to perform
operations such as checking balance, withdrawing money, and
depositing money using switch-case statements for menu options.
Traffic Light Simulator: Write a Java program to simulate a traffic light.
The program should take an integer representing the current state of
the traffic light (1 for red, 2 for yellow, 3 for green) as input and print
out the corresponding action (stop, slow down, go) using a switch-
case statement.
Simple Menu Driven System: Create a Java program that
implements a simple menu-driven system. The program should
display a menu with options such as add, delete, update, and exit.
Implement each option
using switch-case
statements.

switch-case: Excercise III
Language Selector: Develop a Java program that takes an integer
representing a language (1 for English, 2 for Spanish, 3 for French,
etc.) as input and prints out a greeting message in the selected
language using switch-case statements.
Season Identifier: Write a Java program that takes an integer
representing a month (1 for January, 2 for February, etc.) as input and
prints out the corresponding season (spring, summer, fall, winter)
using a switch-case statement.
Simple Game: Develop a Java program for a simple game where the
user guesses a number between 1 and 10. The program should
generate a random number and compare it with the user’s guess.
Provide feedback using switch-case statements to indicate if the
guess was too high, too low, or correct.

Predict the output (switch-case) I
Snipet 1
int x = 3; String
result; switch (x)
{
case 1:
case 2:
result = "One or Two";
break;
case 3:
case 4:
result = "Three or Four";
break;
default:
result = "Other";
}
System.out.println(result);

Predict the output (switch-case) II
Snipet 2
int day = 7; String
dayOfWeek; switch
(day) {
case 1:
dayOfWeek = "Monday";
break;
case 2:
dayOfWeek = "Tuesday";
break;
case 3:
dayOfWeek = "Wednesday";
break;
case 4:
dayOfWeek = "Thursday";
break;
case 5:
dayOfWeek = "Friday";
break;
default:
dayOfWeek = "Weekend";
}
System.out.println(dayOfWeek);

Predict the output (switch-case) III
Snipet 3
char grade = 'B';
String message;
switch (grade) {
case 'A':
message = "Excellent!";
break;
case 'B':
message = "Good!";
break;
case 'C':
message = "Average";
break;
default:
message = "Need Improvement";
}
System.out.println(message);

Predict the output (switch-case) IV
Snipet 4
int month = 9;
String season;
switch (month) {
case 12:
case 1:
case 2:
season = "Winter";
break;
case 3:
case 4:
case 5:
season = "Spring";
break;
case 6:
case 7:
case 8:
season = "Summer";
break;
case 9:
case 10:
case 11:
season = "Autumn";
break;
default:
season = "Invalid month";
}
System.out.println(season);

Predict the output (switch-case) V
Snipet 5
int num = 10; String
result; switch (num %
2) {
case 0:
result = "Even";
break;
case 1:
result = "Odd";
break;
default:
result = "Not an integer";
}
System.out.println(result);

Predict the output (switch-case) VI
Snipet 6
int marks = 75;
String grade;
switch (marks / 10) {
case 10:
case 9:
grade = "A";
break;
case 8:
grade = "B";
break;
case 7:
grade = "C";
break;
case 6:
grade = "D";
break;
default:
grade = "F";
}
System.out.println(grade);

Predict the output (switch-case) VII
Snipet 7
int month = 2;
int year = 2024;
int days;
switch (month) {
case 1:
case 3:
case 5:
case 7:
case 8:
case 10:
case 12:
days = 31;
break;
case 4:
case 6:
case 9:
case 11:
days = 30;
break;
case 2:
if ((year % 4 == 0 && year % 100 != 0)
|| (year % 400 == 0))
days = 29;
else
days = 28;
break;
default:
days = -1;
}
System.out.println("Number of days: " + days);

Session 2
Session 2 will be continued with loop structures in
java

Java Control Structure Session 1 Complete (1).pptx

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