Hi Friends !!!! Today I am going to tell about how decision statements are used in java language..
Decision
statements !!
First of all,as the word define decision,,these are
those statements in which we decide weather which one statement is right or
which one is wrong,……In Java ,we
generally use 2 types of decision making statements:1)
if statements2)
switch statements
If
statement:
This statement is generally used when the given
condition inside if statement is right .Then that block
of code executes which is inside the if statement….
Or
We can say , An if
statement consists of a Boolean expression followed by one or more statements.
Syntax:
if(Boolean_expression)
{
//Statements will execute if the Boolean expression is true
}
Example Of If Statement:
public class abc
{
public static void main(String args[])
{
int x = 5;
if( x < 20 )
{
System.out.print("if statement");
}
}
}
Output
if statement
The
if …else statement:
When we have both the situation,true and false then
this statement will be used Or in technical terms ,we can say that
An if statement can be followed by an optional else
statement, which executes when the Boolean expression is false.
Syntax:
if(Boolean_expression){
//Executes when the Boolean expression is true
}else{
//Executes when the Boolean expression is false
}
Example of if...else Statement:
public class abc
{
public static void main(String args[])
{
int x = 5;
if( x < 20 )
{
System.out.print("if statement");
}
else
{
System.out.print(" else statement");
}
}
}
Output:
if statement
The
if…elseif…else statement:
An if statement can be followed by an optional else
if...else statement, which is very usefull to test various conditions using
single if...else if statement.
When using if , else if , else statements there are few
points to keep in mind.
·
An if can have zero or one else's and it must come after
any else if's.
·
An if can have zero to many else if's and they must come
before the else.
·
Once an else if succeeds, none of he remaining else if's
or else's will be tested.
Syntax:
if(Boolean_expression 1){
//Executes when the Boolean expression 1 is true
}else if(Boolean_expression 2){
//Executes when the Boolean expression 2 is true
}else if(Boolean_expression 3){
//Executes when the Boolean expression 3 is true
}else {
//Executes when the none of the above condition is true.
}
Example of if....elseif..else Statement:
public class abc {
public static void main(String args[]){
int x = 5;
if( x == 1 )
{
System.out.print("Value of X is 1");
}
else if( x == 2)
{
System.out.print("Value of X is 2");
}
else
{
System.out.print("else statement");
}
}
}
output:
else statement
This means we can use use one or more then one if…else
statement inside a if.. else statement
Syntax:
if(Boolean_expression 1){
//Executes when the Boolean expression 1 is true
if(Boolean_expression 2){
//Executes when the Boolean expression 2 is true
}
}
Example Of nested if...else Statement:
public class abc
{
public static void main(String args[])
{
int x = 1;
int y = 2;
if( x == 1 ){
if( y == 2){
System.out.print("X = 1 & Y = 2");
}
}
}
Output:
X=1 & Y=2
In
switch statement,one variable is taken,n the value of variable is checken(prove
to be equal) over a list of case value,if the value is matched then the block
of code inside that statement will execute,.otherwise a default statement will
execute….
Syntax:
switch(expression){
case value :
//Statements
break; //optional
case value :
//Statements
break; //optional
//You can have any number of case statements.
default : //Optional
//Statements
}
Example Of Switch Statement:
public class abc
{
public static void main(String args[])
{
char gd = args[0].charAt(0);//this is the declaration of variable of char datatype
switch(gd)
{
case 'A' :
System.out.println("AWESOME");
break;
case 'B' :
System.out.println("AWKWARD");
break;
default :
System.out.println("Invalid gd");
}
System.out.println("Your grade is " + gd);
}
}
output:
suppose we have to press A
then,
AWESOME
your grade is A
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