Java if-else statement;-

It is used to check the condition is true or false.

Various types of if-else statement:-

• if statement.
• if-else statement.
• if-else-if ladder.
• nested if statement.

If statement;-

It executes the if block if condition is true otherwise not executed.

Syntax of the if statement;-

If(test the expression)

{

// statements to be executed if the test expression is true.

}

Example-

 class Student

 {  

public static void main(String[] args) 

{  

 int age=25;  
 if(age>18)
{  
 System.out.println(“Eligible for Vote”); 
    }  
}  
}  
Output-

Eligible for Vote.

If-else statement;-

It executes if part if the condition is true otherwise they execute else part.

Syntax-

if (test expression) 
{
    // statements to be executed if the test expression is true
}
else
 {
    // statements to be executed if the test expression is false
}

Example-

class Student
{
public static void main(String args[])
{
int a=10;
if(a%2==0)
{
System.out.println(“number is even”);
}
else
{
System.out.println(“number is odd”);
}
}
}
Output-
number is even.

if-else-if ladder;-

The if...else ladder allows you to check between multiple test expressions and execute different statements.

Syntax-

if (test expression1) 
{
   // statement(s)
}
else if(test expression2) 
{
   // statement(s)
}
else if (test  expression3) 
{
   // statement(s)
}
.
.
else 
{
   // statement(s)
}

Example-

class Student
 {  
public static void main(String args[])
 {  
    int age=38;  
    if(age>90)
{  
        System.out.println("dead");  
    }  
    else if(age>=0 && age<12)
{  
        System.out.println("child");  
    }  
    else if(age>=13 && age<22)
{  
        System.out.println("teenager");  
    }  
    else if(age>=23 && age<50)
{  
        System.out.println("younger");  
    }  
    else if(age>=51&& age<89)
{  
        System.out.println("older");  
   } 
  }  
}  
Output-
Younger.

nested if statement-;

The nested if statement represents the if block within another if block. Here, the inner if block condition executes only when outer if block condition is true.

Syntax:

if(condition){    
 //code to be executed    
  if(condition){  
   //code to be executed    
 }    
}  

Example-

class Student
 {    
public static void main(String args[])
 {    
  int age=30;  
  int weight=70;    
  if(age>=18)
{    
 if(weight>55)
{  
 System.out.println("You are eligible to donate blood");  
   } }    
}
}  
Output-
You are eligible to donate blood.