Overview

Control structures are basic blocks that analyze variables and chooses a direction in which to go based on given parameters. Flow control details the direction the program takes. Hence it is the basic decision-making process in computing. The flow control determines how a computer will respond when given certain conditions and parameters.

If..else Example:

A control structure is a decision that the program makes. Let us see a simple example, below a sample piece of code:

package com.testingdocs.sample.programs;

public class JavaIFExample 
{
  
  public static void main(String[] args)
   {
    
    int dummyVariable = 70 ;
    if(dummyVariable == 70 ) 
    { 
      System.out.println("Inside : dummyVariable = " + dummyVariable);
      }
    
    if(dummyVariable > 100)
    { 
      System.out.println("dummyVariable > 100 ");
    } 
    else 
    { 
      System.out.println("dummyVariable < 100 "); }
   	           
   }

}

 

Output of the program:

Inside if : dummyVariable = 70
dummyVariable < 100

 

 

What will happen inside the if..else control structure, depends on the value assigned to the variable. The program output depends on what value we pass the the variable. The program executes the code depending on the value of dummyVariable in the above program.

 

switch statement

switch statement can have a number of possible execution paths. Use switch to specify many alternative blocks of code to be executed.Example below:

package com.testingdcos.examplescripts;

public class SwitchExample {
  
  
      public static void main(String[] args) {

          int weekday = 3;
          switch (weekday) {
              case 1:  System.out.println("Sunday"); break;
              case 2:  System.out.println("Monday"); break;
              case 3:  System.out.println("Tuesday"); break;
              case 4:  System.out.println("Wednesday"); break;
              case 5:  System.out.println("Thursday"); break;
              case 6:  System.out.println("Friday"); break;
              case 7:  System.out.println("Saturday"); break;
              
              default: System.out.println("Not in week!! ");break;
          }
      }
  }