IF & IF ELSE

If Statement in Java Programming : Conditional Selection

Flow of If Statement

1. The if statement is a conditional branch statement.
2. It tells your program to execute a certain section of code only ' if ' a particular test evaluates to true.
3. If boolean Expression evaluates to true, the statements in the block following the if statement are executed.
4. If it evaluates to false, the statements in the if block are not executed.

Syntax : If Statement

if (boolean == true) {

    statement(s)  // execute

}

4. If boolean Expression evaluates to false and there is an else block, the statements in the else block are executed.

Syntax : If-Else Statement

if (boolean == false) {

    statement(s) 

} else {

    statement(s)  // execute

}

Syntax : If - Else  Ladder Statement

5. If we have multiple conditions then we can use if-else ladder –

if (booleanExpression1) {

    // statements

} else if (booleanExpression2) {   // multiple coditions working in steps 

    // statements

}

else {    // statements

}

---

Example 1 : Simple If-Else Ladder Statement

class IfExample {

    public static void main(String[] args) {

        int marks = 55;   // marks is int holding integer 76

        String result;    // result is String holding String in double quotation

        if (marks >= 40) {         // condition   is true   

            result = "Pass";       // statement     executed

        }

        if (marks < 40) {

            result = "Fail";

        }

        System.out.println("Result = " + result);   // print line on console

    }

}

Output :

Result = Pass

Example 2 : Simple If-Else Ladder Statement

class IfExample {

    public static void main(String[] args) {

        int marks = 35;

        String result;

        if (marks >= 40) {           // false Statement

            result = "Pass";

        }

        else

        {

            result = "Fail";        //     executed

        }

        System.out.println("Result = " + result);

    }

}

Output :

Result = Fail

Example 3 : Simple If-Else Ladder Statement

class IfElseExample {

    public static void main(String[] args) {

        int marks = 73;

        char result;

        if (marks >= 90) {

            result = 'A';

        } else if (marks >= 80) {

            result = 'B';

        } else if (marks >= 70) {

            result = 'C';

        } else if (marks >= 60) {

            result = 'D';

        } else {

            result = 'F';

        }

        System.out.println("Result = " + result);

    }

}

Output :

Grade = C

Example 4 : Multiple conditions inside If

if(marks > 70 || marks < 90)


        System.out.println("Class A");


else

        System.out.println("Class B");

1.   We can use “&&” , “||” operators in order to refine condition.
2.   && operator will check whether both left hand and right hand conditions are true or not.
3.   || condition will check

IMPORTANT NOTE :

If we have written two conditions inside “If Condition” then –

1. If First Condition is true then || operator will skip checking second condition.
2. If First Condition is false then || operator will check second condition if second condition is true then overall if will follow true block otherwise it will follow else block.

Proof –

class Test

{

 public static void main(String args[])

  {

  int number1 = 50;

  int number2 = 70;

  if  ((++num1 > 0) || (++num2 > 0))

     {

     System.out.println(num1);

     System.out.println(num2);

     }

  }

}

Output :

50

70