If - Else control statement

In this article we will learn about If-else control statement. There are four types of if-else control statement.

if statement

Syntax

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

Program

public class If_Example
{
    public static void main(String args[])
    {
        int age = 20;
        if(age > 18)
        {
            System.out.println("You can give vote.");
        }
    }
}


  

Output

You can give vote.
  

Explanation

If statement executes the block if the condition becomes true.

if-else statement

Syntax

if(condition)
{  
    //code if condition is true  
}
else
{  
    //code if condition is false  
}  

Program

public class IfElse_Example
{
    public static void main(String args[])
    {
        int age = 17;
        if(age > 18)
        {
            System.out.println("You can give vote.");
        }
        else
        {
            System.out.println("You can't give vote.");
        }
    }
}
  
  

Output

You can't give vote.
  

Explanation

If condition becomes true then if block will be executed. otherwise else block will be executed.

nested if statement

Syntax

if (condition1) 
{
   // Executes when condition1 is true
   if (condition2) 
   {
      // Executes when condition2 is true
   }
   else
   {
       // Executes when condition2 is false
   }
}

Program

public class Nested_If
{
    public static void main(String args[])
    {
        int age = 20;
        if(age > 18)
        {
            System.out.println("You can give vote.");
            if(age % 2 == 0)
            {
                System.out.println("Your age is even.");
            }
            else
            {
                System.out.println("Your age is odd.");
            }
        }
    }
}
  
  

Output

You can give vote.
Your age is even.
  

Explanation

If condition becomes true it executes statement of if block. if there is another if block exists it checks condition if condition becomes true then if block will be executed otherwise else block will be executed.

if-else-if ladder

Syntax

if(condition1){  
//code to be executed if condition1 is true  
}else if(condition2){  
//code to be executed if condition2 is true  
}  
else if(condition3){  
//code to be executed if condition3 is true  
}  
...  
else{  
//code to be executed if all the conditions are false  
}  

Program

public class IfElse_leader
{
    public static void main(String args[])
    {
        int age = 22;
        if(age < 12)
        {
            System.out.println("You are child.");
        }
        else if(age > 12 && age < 20)
        {
            System.out.println("You are teenager.");
        }
        else if(age > 20 && age < 50)
        {
            System.out.println("You are mature.");
        }
        else
        {
            System.out.println("You are old.");
        }
    }
}
  
  

Output

You are mature.
  

Explanation

Here, if condition becomes true then it's block will be executed and rest of the condition will be ignored. If all conditions become false then else block will be executed.