Java Control Statements



If Else Statement in Java:

In If Else statement a series of Boolean values become Check when condition become true that block of code Execute.

If Condition – In Java program when if condition become true then if block code become Execute.

Else Condition– When if condition Become false then else block code Execute  

Else If Condition– Else if statement is used to Check New condition in Else Block.  

      
Control Statement Flow:

If Else Statement Example:

public class My_First_Test {
   public static void main(String args[]) {
      int x = 30;
      if( x == 10 ) {
         System.out.print(“Value of X is 10”);
      }else if( x == 20 ) {
         System.out.print(“Value of X is 20”);
      }else if( x == 30 ) {
         System.out.print(“Value of X is 30”);
      }else {
         System.out.print(“This is else statement”);
      }
   }
}
Output:

Compiling the source code….
$javac My_First_Test.java 2>&1


Executing the program….
$java -Xmx128M -Xms16M My_First_Test

Value of X is 30
Switch Statement in Java:

In switch, statement a variable is checked from list of Condition or values. Each value is called a case, and the variable being switched on is checked for each case.

Switch Statement Flow:

Important Note About switch statement −
  • Variable use in a switch statement only be integers, convertable integers (byte, short, char), strings and enums.
  • You can use any number of case statements within a switch.
  • When the variable being switched on is equal to a case, the statements following that case will execute until a break statement is reached.
  • When a break statement is reached, the switch terminates, and the flow of control jumps to the next line following the switch statement.
  • Not every case needs to contain a break. If no break appears, the flow of control will fall through to subsequent cases until a break is reached.
  • A switch statement can have an optional default case, which must appear at the end of the switch. The default case can be used for performing a task when none of the cases is true. No break is needed in the default case.



Switch Statement Example:

public class Test {
 
   public static void main(String args[]) {
      // char grade = args[0].charAt(0);
      char grade = 'C';
 
      switch(grade) {
         case 'A' :
            System.out.println("Excellent!"); 
            break;
         case 'B' :
         case 'C' :
            System.out.println("Well done");
            break;
         case 'D' :
            System.out.println("You passed");
         case 'F' :
            System.out.println("Better try again");
            break;
         default :
            System.out.println("Invalid grade");
      }
      System.out.println("Your grade is " + grade);
   }
}
Output
Well done
Your grade is C

Let’s us understand Difference between If Else and Switch Statements

if-else Statements
Switch Statements
if-else can be used for a range of values
switch-case is valid only for cases where we have a specific set of outputs
if-else can handle integers, not fractional values.
switch-case only accepts integers, not fractional values.
if-else is difficulty to when large number of conditions.
switch case is Easily readability and understand for a large number of conditions.
Where to use If-else: When simple and Few Comparisons
Where to use Switch:  when Complex and large Comparisons.

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