Difference between revisions of "Java/C2/if-else/English-timed"

| Welcome to the spoken tutorial on '''If else constructs '''in java.  

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| In this tutorial we will learn:

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| * About conditional statements

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| *  types of conditional statements and

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| * How to use conditional statements in Java programs

|  For this tutorial we are using:

Ubuntu v 11.10

 

Eclipse 3.7.0  

| To follow this tutorial you should have knowledge of using  

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| * '''Arithmetic''', '''Relational''' and '''Logical''' '''operators''' in '''Java'''

| If not, for relevant tutorials please visit our website which is as shown.

|'' Conditional statements'' You may have to perform different actions for different decisions in your code.

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| In such cases you can use conditional statements.

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| A conditiona statement helps to control the flow of execution of a program.  

 

 

 

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| In Java we have the following conditional statements:

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| * Nested If statement

| * Switch statement

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| In this tutorial, we will learn about '''If, If...Else and If...Else If statements''' in detail.

| | '''If statement ;'''is used to execute a block of statements based on a condition.  

 

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|   ''Syntax for If statement ;'''

 

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| In the '''if statement, '''if the condition is '''true,''' the block is executed.

 

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| If the condition is '''false, '''the block is skipped and it is  not executed.

 

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|   now Let us look at an example to understand how the '''If Statement''' can be used.

 

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| So Let us switch to '''eclipse.'''

 

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| I have already created a class '''Person.'''

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| Now, inside the main method let us declare a variable '''‘age’''' of type '''int.'''

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|  02:14

|Now, we will write an If statement as follows:

 

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|Next line '''''if '''within  bracket '''age < 21 '''  open curly brackets.'' Press enter

 

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| Whatever is inside the brackets belongs to the if block.

 

|So Inside the brackets type

 

| '''System '''''dot '''''out '''''dot '''''println '''within brackets and double quotes''' The person is Minor semi-colon.'''

 

| Here, if '''age '''is less than '''21,''' than “'''The person is minor'''” will be displayed.

 

|  So   '''save''' and''' run '''the file.

| We get the output as follows. The person is minor

 

 

| In this case, the person's age is''' 20''', which is less than '''21. '''

| So, we got the output as “'''The person is minor'''”.

 

|Now, we will learn about '''if...else '''statement.

 

| If...Else statement is used to execute alternative statements.

 

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|   03:34

| Let us look at the syntax for writing   '''If…Else statement.'''

 

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| If the condition is True,  the statement or block of code is executed..

 

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| Else it executes another statement or  block of code.

|  We will now see how the '''If…else statement ;'''can be used in a program.

| So let us switch to the eclipse.

|   we will now  write a program to identify whether the person is '''Minor or Major'''.

 

| So inside the '''Main''' method type; int age is equal to 25

 

|  then '''if '''''within brackets'' '''age''' ''greater than'' '''21''',

|   ''within curly brackets'' type '''System '''''dot''''' out '''''dot''''' println '''''within brackets '''''The person is Major.'''

 

| Then type,next line  

| '''else '''''within curly brackets'' type

| '''System''' ''dot '''''out''' ''dot'' '''println '''''within brackets''in double quotes  '''The person is Minor semi-colon.'''

 

| Here, if  '''age''' ''is less than'' '''21''',  “' ''The person is Minor'''” will be displayed.

 

| '''Else''' the “'''The person is Major” '''will be displayed.

 

| See now Let us'''save   '''and''' run''' the program.

| We get the output as the person is major

| Here, the person's '''age''' is '''25,''' which is greater than '''21'''.  

 

| Therefore the program  display the output as “'''The person is Major'''”.

 

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|  '''If…Else If''' statement is used to execute various set of statements.

 

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| It is also called as  ''' branching '''or '''decision making statement.'''

 

 

 

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| Now Let us look at the syntax for writing  '''If…Else If '''statement.

 

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| If statement initially checks for '''condition 1.'''

 

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| If''' condition 1 '''is true, it executes the '''statement   '''or '''block code '''.

 

| Else it again checks for '''condition 2.'''  

 

| If '''condition 2''' is true, it executes '''statement   '''or '''block   2'''.

 

| Else it executes '''statement 3''' or '''block code 3'''.

 

| These blocks can have multiple conditions.  

 

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|   We will see how the '''If…Else If statement ;'''can be used in a program.

 

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| So switch to Eclipse.

 

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| I have already created a class named Student.

 

| Let us write a program to identify grade of a student.

 

| So inside   the''' Main''' method, type '''int''' ''space''''' testScore''' ''equal to''''' 70''' ''semicolon.''

 

| The input variable named ‘'''testScore'''’ is used to get the score percentage.

 

| Next line type''' if''' ''within brackets'' '''testScore''' ''  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 '''

 

|  next line type '''if'' '''within brackets''''' testScore '''''greater than or equal to'' '''35 '''and '''testScore '''''less than or equal to '''''60.'''Put the whole condition within brackets open curly brackets press enter.

| Type '''System dot out dot println''' within brackets ''' B grade''' semi-colomn

| 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''.

 

|  So Finally, if both the conditions are '''False''', the program displays “'''A Grade'''".  

 

| We get the output as '''A Grade'''

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| In this program, the student’s '''testScore''' is '''70''' .

 

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| So the output will be displayed as “'''A Grade'''”.

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| Now  Let us change the''' testScore''' to''' 55.'''  

 

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| In this case, the output will be displayed as “'''B Grade'''”.

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| We can also increase the number of conditions.

 

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| Let us add one more condition after the “'''B grade'''” output section.

 

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Else, Next line

'''if''' ''within brackets''''' testScore''' ''greater than or equal to'' '''60 '''and''' testScore''' ''less than or equal to'' '''70.'''

 

| Open curly brackets press enter  '''System '''''dot '''''out''' ''dot '''''println''' ''within brackets and double quotes''''' O grade''' ''semicolon''.

 

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| Here if the '''testScore''' is between '''60''' and '''70'''    the program will display "'''O Grade'''".

 

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| Now, change the '''testScore''' of the student to''' 70'''.  

 

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| | We get the output as follows.

 

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| 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 '''70.'''

|   While coding conditional structures:

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| * Always remember to add a semicolon while terminating a statement.

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| * But don’t add semi-colons after the condition.

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| * Add the block of code within curly brackets

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| * Curly braces are optional if the block contains a single statement.

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| We have  Explained conditional statements

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| * Listed the types of conditional statements

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| * Used conditional statements: '''if, if...else and if...else if''' in Java programs.

|Now take an assignment on writing java programs using conditional statements: '''if, if...else and if...else if '''statements.

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| * Write a java program to check whether the given number is even or odd.

 

Hint : use '''if...else '''statement.

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| * Write a java program to find the biggest number among the three numbers.

 

Hint : use '''if...else if '''statement.

 

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|   12:15  

| This script has been contributed by TalentSprint. This is Arya. Ratish from IIT Bombay signing off