| Visual cue
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Narration
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| Slide 1
Welcome
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Welcome to the spoken tutorial on If else constructs in java.
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| Slide 2
Learning Objectives
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In this tutorial we will learn:
- About conditional statements
- The types of conditional statements and
- How to use conditional statements in Java programs
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| Slide 3
Tools Used
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For this tutorial we are using:
Ubuntu 11.10
JDK 1.6
Eclipse 3.7
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| Slide 4
Pre-requisites
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To follow this tutorial you should have knowledge of using
- Arithmetic, Relational and Logical operators in Java
If not, for relevant tutorials please visit our website which is as shown.
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| Slide 5
Conditional Statements
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You may have to perform different actions for different decisions in your code.
In such cases you can use conditional statements.
A conditional statement helps to control the flow of execution of a program.
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| Slide 6
Types of Conditional Statements
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In Java we have the following conditional statements:
- If statement
- If...Else statement
- If...Else if statement
- Nested If statement
- Switch statement
In this tutorial, we will learn about If, If...Else and If...Else If statements in detail.
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| Slide 7
If Statement
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If statement is used to execute a block of statements based on a condition.
It is called a single conditional statement.
It is also called branching or decision making statement.
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| Slide 8
Syntax for If statement
if (condition)
{
code_block;
}
// end of if construct
// program continues here
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Let us look at the syntax for writing if statement.
In the if statement, if the condition is true, the block is executed.
If the condition is false, the block is skipped and not executed.
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| Example of If statement
(Minimize the slide and in the Eclipse tool, type the program according to the explanation)
class Person
{
public static void main(String args[]) {
int age=20;
if(age<21) {
System.out.println("The person is Minor");
}
}
}
Highlight when you explain
Highlight {}
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Let us look at an example to understand how the If Statement can be used.
Let us switch to eclipse.
We will write a program to identify whether a person is Minor.
I have already created a class Person.
Now, inside the main method let us declare a variable ‘age’ of type int.
So type int age is equal to 20.
Now, we will write an If statement as follows:
if within parentheses age < 21 curly brackets.
Here, we are checking if age is less than 21.
Whatever is inside the brackets belongs to the if block.
Inside the brackets type
System dot out dot println within brackets and double quotes The person is Minor.
Here, if age is less than 21, then “The person is minor” will be displayed.
Let us save and run this file.
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| Highlight the output.
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We get the output as follows.
In this case, the person's age is 20, which is less than 21.
So, we got the output as “The person is minor”.
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| Slide 9
(Restore the slide)
If…Else statement
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Now, we will learn about if...else statement.
If...Else statement is used to execute alternative statements.
These are based on a single condition.
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| Slide 10
Syntax for If…Else statement
if ( <condition> )
<statement_or_block>
else
<statement_or_block>
// end of if construct
// program continues here
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Let us look at the syntax for writing the If…Else statement.
If the condition is True, then the statement or block of code is executed..
Else it executes another statement or another block of code.
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| Example of If…Else statement
(Please include the example in Eclipse. No need to show it on slide. Show how to run the program in Eclipse and then point to the output at the console.)
Type the code in Eclipse as per the explanation.
class Person
{
int age=25;
public static void main(String args[])
{
if(age>21)
{
System.out.println("The person is Major");
}
else
{
System.out.println("The person is Minor");
}
}
}
Highlight as you explain.
|
We will now see how the If…else statement can be used in a program.
Now, we will write a program to identify whether the person is Minor or Major.
So inside the Main method type
if within brackets age greater than 21,
then within curly brackets type System dot out dot println within brackets The person is Major.
Then type
else within curly brackets type
System dot out dot println within brackets The person is Minor.
Here, if the age is less than 21, then “The person is Minor” will be displayed.
Else the “The person is Major” will be displayed.
Now, save and run the program.
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| Highlight the output and explain.
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We get the output as follows.
Here, the person's age is 25, which is greater than 21.
Therefore the program will display the output as “The person is Major”.
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| Slide 11
(Restore the slide)
If…Else If statement
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If…Else If statement is used to execute various set of statements.
These are based on the two given conditions.
You can also add more conditions based on your requirement.
It is also called as a branching or decision making statement.
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| Slide 12
Syntax for If…Else If statement
if ( <condition 1> )
<Statement_or_block 1>
else if (<condition 2>)
<Statement of block 2>
else
<Statement_or_block 3>
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Let us look at the syntax for writing the If…Else If statement.
This statement initially checks for condition 1.
If condition 1 is true, it executes the statement 1 or block code 1.
Else it again checks for condition 2.
If condition 2 is true, it executes statement 2 or block code 2.
Else it executes statement 3 or block code 3.
In this way, we can extend the code by If…Else blocks.
These blocks can have multiple conditions.
The corresponding code will get executed until it finds the true condition.
If all the conditions are false, it will execute the final Else section.
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| Example of If…Else If statement
(Minimize the slide and type the code according to the audio narration)
class Student
{
public static void main(String args[])
{
int testScore=70;
if(testScore<35)
{
System.out.println("C grade ");
}
else if((testScore>=35)&&(testScore<=60))
{
System.out.println("B grade");
}
else
{
System.out.println("A grade");
}
}
}
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We will see how the If…Else If statement can be used in a program.
So switch to Eclipse.
I have already created a class named Student.
Let us write a program to identify grade of a student.
This is done based on the score percentage.
In the Main method, type int space testScore equal to 70 semicolon.
The input variable named ‘testScore’ is used to get the score percentage.
Then type if within brackets testScore is less than 35, within curly brackets System dot out dot println within brackets and double quotes C grade semicolon.
If the testScore is less than 35, then the program displays "C Grade".
Next line type else
Then next line type if within brackets testScore greater than or equal to 35 and testScore less than or equal to 60.
Here, the program will check for the second condition in the Else If section.
If the testScore is between 35 and 60 then the program displays "B Grade".
Next line type else within brackets type System dot out dot println within brackets and double quotes A grade semicolon.
Finally, if both the conditions are False, the program displays “A Grade".
Now, let us save and run this code.
.
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| Highlight the output and explain
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We get the output as follows.
In this program, the student’s testScore is 70 .
So the output will be displayed as “A Grade”.
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| Change testScore=55;
|
Let us change the testScore to 55.
Now, save and run this program.
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| Highlight the output as you explain.
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We get the output as follows.
In this case, the output will be displayed as “B Grade”.
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| else if((testScore>=60)&&(testScore<=75))
{
System.out.println("O grade");
}
Highlight as you explain.
|
We can also increase the number of conditions.
Let us add one more condition after the “B grade” output section.
So type here, if within brackets testScore greater than or equal to 60 and testScore less than or equal to 75.
Then within curly brackets type System dot out dot println within brackets and double quotes O grade semicolon.
Here if the testScore is between 60 and 75 then the program will display "O Grade".
Now, change the testScore of the student to 70.
Now, save and run the file.
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| Highlight the output.
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We get the output as follows.
The program will display the output as “O grade”.
It is not “A grade” as it displayed before.
The program will display “A grade” for the testScore greater than 75.
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| Slide 13
Points to Remember
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While coding conditional structures:
- Always remember to add a semicolon while terminating a statement.
- But don’t add semi-colons after the condition.
- Add the block of code within curly braces.
- Curly braces are optional if the block contains a single statement.
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| Slide 14
Summary
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We have come to the end of this tutorial.
In this tutorial, we:
- Explained conditional statements
- Listed the types of conditional statements
- Used conditional statements: if, if...else and if...else if in Java programs.
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| Slide 15
Assignment
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Now take an assignment on writing java programs using conditional statements: if, if...else and if...else if statements.
- Write a java program to compare two values using if statement.
- Write a java program to check whether the given number is even or odd.
Hint : use if...else statement.
- Write a java program to find the biggest number among the three numbers.
Hint : use if...else if statement.
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| Slide 16
About the Spoken Tutorial Project
- It summarizes the Spoken Tutorial project
If you do not have good bandwidth, you can download and watch it
|
To know more about the Spoken Tutorial project,
watch the video available at the following link.
It summarizes the Spoken Tutorial project.
If you do not have good bandwidth, you can download and watch it
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| Slide 17
Spoken Tutorial Workshops
The Spoken Tutorial Project Team
- Conducts workshops using spoken tutorials
- Gives certificates for those who pass an online test
For more details, please write to contact@spoken-tutorial.org
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The Spoken Tutorial Project Team
- Conducts workshops using spoken tutorials
- gives certificates for those who pass an online test. For more details, please write to contact AT spoken HYPHEN tutorial DOT org.
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| Slide 18
Acknowledgement
- Spoken Tutorial Project is a part of the Talk to a Teacher project
- It is supported by the National Mission on Education through ICT, MHRD, Government of India
- More information on this Mission is available at
http://spoken-tutorial.org/NMEICT-Intro
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Spoken Tutorial Project is a part of the Talk to a Teacher project and is supported by the National Mission on Education through ICT, MHRD, Government of India. More information on this Mission is available at spoken HYPHEN tutorial DOT org SLASH NMEICT HYPHEN Intro
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| Slide 19
About the contributor
- This tutorial has been contributed by TalentSprint
- Website: www.talentsprint.com
Thanks for joining
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This tutorial has been contributed by TalentSprint.
Thanks for joining
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