Java/C2/Logical-Operations/English

Title of script: Logical Operators in Java

Author: TalentSprint

Keywords: boolean, comparison, logical operator, video tutorial

Visual Cue	Description
Slide 1 Welcome	Welcome to the spoken tutorial on Logical Operators in Java.
Slide 2 Learning Outcomes	In this tutorial, you will learn about the logical operators in java and how to check for multiple expressions using logical operators and how to overwrite precedence using parentheses
Slide 3 Tools Used	For this tutorial we are using Ubuntu 11.10, JDK 1.6 and Eclipse 3.7
Slide 4 Prerequisites	For this tutorial, you should have knowledge on relational operators in Java If not, for relevant tutorials, please visit our website as shown.
Slide 5 Logical Operators	Logical operators are used to check multiple conditions. Here is a list of the available logical operators in Java
	and, or, not. We shall look into each of them in detail. Switch to Eclipse.
Minimize Slides and open Eclipse Eclipse should contain the following code public class LogicalOperators{ public static void main(String[] args){ } }	We have the Eclipse IDE and skeleton required for the rest of the code. We have created a class LogicalOperators and added the main method to it. Let us create some variables.
In the main function, type int age = 11; int weight = 42;	boolean b; We shall store the result of conditions in b; Type int age is equalto 11 semi-colon. int weight isequalto 42 semi-colon.
Highlight int age = 11; int weight = 42;	We have the age and weight of a person. We shall check if the person is below 18yrs of age and is atleast 40kgs. Let us see how to do so.
Type after the previous line, boolean b; b = age < 18 && weight >= 40 Highlight && Highlight expression	Type, age less than 18 ampersand ampersand weight greater than equal to 40 This statement has two expressions and a double ampersand symbol in between. This condition checks if age is less than 18 and also if weight is greater than or equal to 40. This operation is called the and operation.
Put the line age... inside the statement System.out.println();	Let us now print the value. System dot out dot println(b);
Save and Run.	Save and Run the program.
Point to output Change 42 to 32. Save and Run.	As we can see, the output is true because both the conditions are satisfied. Now let us change the weight so that one condition is not satisfied and re run the code. Change 42 to 32. Save and Run the program.
Point to output	As we can see, the output is now false. This is because the condition age is less than 18 is true. But the condition the weight is not greater than or equal to 40 is false. The and operation requires both the conditions to be true for the result to be true. Therefore we get false as our output.
	This way, we use a double ampersand to do an and operation.
	Lets say we have age and weight and it is enough if one of the conditions is satisfied. In other words, we need to see if the first condition or the second condition is true. It is done using the or operation.
Comment out the old condition and type b = age <= 15 || weight <= 30	Let us first remove the earlier condition. Type age less than equal to 15 pipe pipe weight less than equal to 30 There are two conditions and a double pipe symbol in between. This statement checks if atleast one of the given two conditions is satisfied. Let us run the code to see the output.
Save and Run	We see that the output is True.
	This is because, an or operation, does not need both the conditions to be true like the operation.
	It needs atleast one condition to be true.
	So although the condition for weight is not satisfied, the condition for age is satisfied.
	And we get a true.
	Now let us change the age such a way that both the conditions are false and see the result.
Save and Run.	Save and Run the program.
Change 11 to 17 Save and Run. Point to output	Now change 11 to 17 Save and Run the program. Now the output is false since both the conditions are not satisfied.
	This way, we use a double PIPE symbol to do an and operation.
	Now let us say we need to check for people who are older than 15 and with weight more than 30kilos. In other words, we need to check the exact opposite of the condition we just did.
	In such situations, we use the not operation
Add parentheses around the age... line	First enclose the condition in parentheses.
Add ! before the parentheses.	Add an exclamation mark before the condition.
	By using an exclamation mark, we check for the exact opposite of the condition inside the parentheses.
	This operation is called the not operation
	Since the earlier output was false, now it must be the opposite, true.
Save and Run. Point to output	Save and Run. As we can see, the output is the opposite of earlier one.
Back to code.	Let us say we want people younger than 15. Or people younger than 18 and lighter than 40kilos. Let us see how would we go about this condition.
Remove the System... line and type age < 15 || age < 18 && weight < 40 Highlight the condition.	Type, age less than 15 or age less than 18 and weight less than 40 As we can see, the condition itself is confusing. Moreover, we do not know if the or operation will be performed first or the and operation. It depends on the precedence of operators. In such situations, we use parentheses to overwrite the precedence and also make the condition clear.
Change age <= 18 && weight <= 40 to (age <= 18 && weight <= 40)	So let us add the parentheses. Now the condition is clear. We also make sure that the and operation is performed first and then the or operation.
	Let us run the code. Save. Run.
	Although the first condition age less than 15 is not satisfied, the second condition, which is, age less than 18 and weight less than 40 is satisfied. Therefore, output is True.
	As a rule, use parentheses to avoid ambiguity and make the expressions clear.
	This how we use the logical operators to check for multiple conditions.
Minimize the Eclipse window and switch to slides. Slide 6 Summary	We have come to the end of this tutorial. In this tutorial we have learnt about logical operators, how to check for multiple expressions using logical operators and how to override the precedence using parentheses.
Slide 7Assignment	As an assignment for this tutorial, find out if the two expressions, shown are equivalent?
Slide 8About the Spoken Tutorial Project Watch the video available at[1]http://spoken-tutorial.org/What_is_a_Spoken_Tutorial It summarises 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, that summarises the project. if you do not have good bandwidth, you can download and watch it
Slide 9Spoken Tutorial WorkshopsThe 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	The Spoken Tutorial Project Team. Conducts workshops using spoken tutorials and gives certificates for those who pass an online test. For more details, please write to contact AT spoken HYPHEN tutorial DOT org.
Slide 10Acknowledgement 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	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
Slide 11About the contributor This tutorial has been contributed by TalentSprint www.talentsprint.com Thanks for joining	This tutorial has been contributed by TalentSprint. Thanks for joining.

Contributors and Content Editors

Chandrika, Sneha