Control flow statements : Decision Making: if-then, if-else, if-else if-else

Java provides control flow statements

     for decision making (if, if-else, switch) and

     for looping (for, while, do-while)

Block of statements

In java the statements between { } are called block of statements.

     {

          //block of code

     }

Decision making statements

if statement

“ if ” tell the program execute the section of code when the condition evaluates to true.

     Syntax

          if(condition){

               // Executes if the condition true

          }

Example

class Grades{
 public static void main(String args[]){ 
  int marks = 20;
  if(marks < 35 ){
   System.out.println("You failed in the Exam. Better luck next time");
  }
 }
}

Output

You failed in the Exam. Better luck next time

Some points to remember

1. In java the condition in the if must evaluates to boolean value, other wise compiler will throw error

Example

class Grades{
 public static void main(String args[]){
  int var1;
  if(var1 = 10){
  
  }
 }
}

When you try to compile the above program, you will get the below error

Grades.java:5: error: incompatible types
 if(var1 = 10){
 ^
 required: boolean
 found: int
1 error

if-else statement

    Syntax:

    if(condition){

    }

    else{

    }

If the condition true, then if block code executed. other wise else block code executed.

Example

class Grades{
 public static void main(String args[]){ 
  int marks = 36;
  
  if(marks < 35)
   System.out.println("You are failed");
  else
   System.out.println("You are passed");
 }
}

Output

You are passed

Observation

In the above program we haven't written the if, else block codes in between { }, since if there is only one statement in between the blocks, we can omit { }.

if-else if-else

By using if-else if-else construct, you can choose number of alternatives.

An if statement can be followed by an optional else if...else statement, which is very useful to test various conditions using single if...else if statement.

class Grades{
 public static void main(String args[]){
  int marks = 69;
  
  if(marks < 35)
   System.out.println("You are failed");
  else if( marks < 50)
   System.out.println("You are passed and got third class");
  else if( marks < 60)
   System.out.println("You are passed and got second class");
  else if( marks < 70)
   System.out.println("You are passed and got first class");
  else
   System.out.println("You are passed and got distinction");
 }
}

Output

You are passed and got first class

other Operators                                                 Control flow statements                                                 Home