Programming in java - Concepts- Operators- Control statements-Expressions

Control Statements
Selection
Iteration
Jump
Outlines
1

Selection
If Statements
Switch Statement
 Selection Statements are also called Decision Making Statements.
Selection Statements
2

if Statements
Simple if
if else
if- else- if Ladder
Nested if
if Statements
3

Simple if
4
Syntax :
if (condition)
{
statement1;
}
Purpose: The statements will be evaluated if the value of the condition is true.

Simple if
Start
End
Condition
Statements
False
5
True
Flow Chart:

if else
7
Syntax :
if (condition)
{
statement1;
}
else
{
statement2;
}
Purpose: The statement 1 is evaluated if the value of the condition is true otherwise
statement 2 is true.

if else
False
True
Flow Chart: Start
End
Condition
Statement 1 Statement 2
8

If-else-if Ladder
10
Syntax :
if(condition)
statements;
else if(condition)
statements;
else if(condition)
statements;
...
...
else
statements;

Examples
11
import java.util.Scanner;
class Day
{
public static void main(String args[])
{
Scanner s = new Scanner(System.in);
System.out.println("Enet day between 0 to 6 Day = ");
int day = s.nextInt();
if (day == 0)
{
System.out.println("n Sunday");
}
else if (day == 1)
{
System.out.println("n Monday");
}
else if (day == 2)
{
System.out.println("n Tuesday");
}
else if (day == 3)
{
System.out.println("n Wednesday");
}
else if (day == 4)
{
System.out.println("n Thursday");
}
else if (day == 5)
{
System.out.println("n Friday");
}
else
{
System.out.println("n Saturday");
}
}
}

Nested if
12
• A nested if is an if statement that is the target of another if or else.
• Nested ifs are very common in programming.
Syntax :
if(condition)
{
if(condition)
statements....
else
statements....
}
else
{
if(condition)
statements....
else
statements....
}

switch
14
Syntax :
switch (expression)
{
case value 1 :
statement 1 ; break;
case value 2 :
statement 2 ; break;
...
...
case value N :
statement N ; break;
default :
statements ; break;
}
Purpose: The statements N will be evaluated if the value of the logical expression is true.

switch
Flow Chart:
Case A
Case B
…
default
False
False
False
Case A Statements
break;
Case B Statements
break;
Case C Statements
break;
Default Statements
Start
Variable or Expression
True
True
True
End
15

SWITCH Features
• Switch only tests for equality.
• No 2 case constants in the same switch can have identical values.
• More efficient than nested if’s.
• Faster than if.

Iteration Statements
Iterations/ Loops
while
do while
for
18
Each loop has four types of
statements :
 Initialization
 Condition checking
 Execution
 Increment / Decrement

while
19
Syntax:
initialization
while(final value)
{
statements;
increment/decrement;
}
Purpose: To evaluate the statements from initial value to final value with given
increment/decrement.
m=1
while(m<=20)
{
System.out.println(m);
m=m+1;
}

Example
20
class while1
{
{
int i=1;
while(i<=10)
{
System.out.println("n" + i);
i++;
}
}
}
Output :
1
2
3
4
5
6
7
8
9
10
 print values from 1 to 10

do while
21
Syntax:
initialization
do
{
statements;
increment/decrement;
}
while(final value);
Purpose: To evaluate
the statements from initial value to final value with given
m=1
do
{
m=m+1;
}
while(m==20);

Example
class dowhile1
{
{
int i = 1;
int sum = 0;
do
{
sum = sum + i;
i++;
}while (i<=10);
System.out.println("nntThe sum of 1 to 10 is .. " + sum);
}
}
Output :
The sum of 1 to 10 is .. 55 22

for
23
Syntax:
for(initialization;final value;increment/decrement)
{
statements;
}
Purpose: To evaluate the statements from initial value to final value with given
for(m=1;m<=20;m=m+1)
{
}

Example
24
class for1
{
{
int i;
for (i=0;i<5;i++)
{
System.out.println("nExample of for loop ");
}
}
Output :
Example of for loop
Example of for loop
Example of for loop
Example of for loop
Example of for loop

Nested Loops
Like all other programming languages, Java allows loops to be nested. That is, one loop
may be inside another. For example, here is a program that nests for loops,
// Loops may be nested.
class Nested {
public static void main(String args[]) {
int i, j;
for(i=0; i<10; i++) {
for(j=i; j<10; j++)
System.out.print(".");
System.out.println();
}
}
}

Jump Statements
Jump
break
continue
return
26

The break statement
27
 This statement is used to jump out of a loop.
 Break statement was previously used in switch – case statements.
 On encountering a break statement within a loop, the execution continues with the
statement outside the loop.
 The remaining statements which are after the break and within the loop are skipped.
 Break statement can also be used with the label of a statement.
 A statement can be labeled as follows.
 goto label; break label;
next
statementName : SomeJavaStatement
 When we use break statement along with label as,
break statementName;

Example
28
class break1
{
{
int i = 1;
while (i<=10)
{
i++;
if (i==5)
{
break;
}
}
}
}
Output :
1
2
3
4

continue Statement
29
 This statement is used only within looping statements.
 When the continue statement is encountered, the next iteration starts.
 The remaining statements in the loop are skipped. The execution starts from the
top of loop again.

Example
30
class continue1
{
{
for (int i=1; i<1=0; i++)
{
if (i%2 == 0)
continue;
}
}
}
Output :
1
3
5
7
9

The return Statement
31
 The last control statement is return. The return statement is used to
explicitly return from a method.
 That is, it causes program control to transfer back to the caller of the
method.
 The return statement immediately terminates the method in which it is
executed.

Example
32
class Return1
{
{
boolean t = true;
System.out.println("Before the return.");
if(t)
return; // return to caller
System.out.println("This won't execute.");
}
}
Output :
Before the return.

Programming in java - Concepts- Operators- Control statements-Expressions

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Programming in java - Concepts- Operators- Control statements-Expressions